Merge pull request #3136 from Yawning/feature/crypto-hash

core:crypto/hash - Add and refactor

17 files changed, 1278 insertions, 1914 deletions

diff --git a/core/crypto/README.md b/core/crypto/README.md
index adb815df4..1e4e41fb8 100644
--- a/core/crypto/README.md
+++ b/core/crypto/README.md
@@ -1,84 +1,22 @@
 # crypto
 
-A cryptography library for the Odin language
+A cryptography library for the Odin language.
 
 ## Supported
 
-This library offers various algorithms implemented in Odin.
-Please see the chart below for some of the options.
-
-## Hashing algorithms
-
-| Algorithm                                                                                                    |                  |
-|:-------------------------------------------------------------------------------------------------------------|:-----------------|
-| [BLAKE2B](https://datatracker.ietf.org/doc/html/rfc7693)                                                     | ✔️ |
-| [BLAKE2S](https://datatracker.ietf.org/doc/html/rfc7693)                                                     | ✔️ |
-| [SHA-2](https://csrc.nist.gov/csrc/media/publications/fips/180/2/archive/2002-08-01/documents/fips180-2.pdf) | ✔️ |
-| [SHA-3](https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.202.pdf)                                            | ✔️ |
-| [SHAKE](https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.202.pdf)                                            | ✔️ |
-| [SM3](https://datatracker.ietf.org/doc/html/draft-sca-cfrg-sm3-02)                                           | ✔️ |
-| legacy/[Keccak](https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.202.pdf)                                    | ✔️ |
-| legacy/[MD5](https://datatracker.ietf.org/doc/html/rfc1321)                                                  | ✔️ |
-| legacy/[SHA-1](https://datatracker.ietf.org/doc/html/rfc3174)                                                | ✔️ |
-
-#### High level API
-
-Each hash algorithm contains a procedure group named `hash`, or if the algorithm provides more than one digest size `hash_<size>`\*.
-Included in these groups are six procedures.
-- `hash_string` - Hash a given string and return the computed hash. Just calls `hash_bytes` internally
-- `hash_bytes` - Hash a given byte slice and return the computed hash
-- `hash_string_to_buffer` - Hash a given string and put the computed hash in the second proc parameter. Just calls `hash_bytes_to_buffer` internally
-- `hash_bytes_to_buffer` - Hash a given string and put the computed hash in the second proc parameter. The destination buffer has to be at least as big as the digest size of the hash
-- `hash_stream` - Takes a stream from io.Stream and returns the computed hash from it
-- `hash_file` - Takes a file handle and returns the computed hash from it. A second optional boolean parameter controls if the file is streamed (this is the default) or read at once (set to true)
-
-\* On some algorithms there is another part to the name, since they might offer control about additional parameters.
-For instance, `SHA-2` offers different sizes.
-Computing a 512-bit hash is therefore achieved by calling `sha2.hash_512(...)`.
-
-#### Low level API
-
-The above mentioned procedures internally call three procedures: `init`, `update` and `final`.
-You may also directly call them, if you wish.
-
-#### Example
-
-```odin
-package crypto_example
-
-// Import the desired package
-import "core:crypto/blake2b"
-
-main :: proc() {
-    input := "foo"
-
-    // Compute the hash, using the high level API
-    computed_hash := blake2b.hash(input)
-
-    // Variant that takes a destination buffer, instead of returning the computed hash
-    hash := make([]byte, sha2.DIGEST_SIZE) // @note: Destination buffer has to be at least as big as the digest size of the hash
-    blake2b.hash(input, hash[:])
-
-    // Compute the hash, using the low level API
-    ctx: blake2b.Context
-    computed_hash_low: [blake2b.DIGEST_SIZE]byte
-    blake2b.init(&ctx)
-    blake2b.update(&ctx, transmute([]byte)input)
-    blake2b.final(&ctx, computed_hash_low[:])
-}
-```
-For example uses of all available algorithms, please see the tests within `tests/core/crypto`.
+This package offers various algorithms implemented in Odin, along with
+useful helpers such as access to the system entropy source, and a
+constant-time byte comparison.
 
 ## Implementation considerations
 
 - The crypto packages are not thread-safe.
 - Best-effort is make to mitigate timing side-channels on reasonable
-  architectures. Architectures that are known to be unreasonable include
+  architectures.  Architectures that are known to be unreasonable include
   but are not limited to i386, i486, and WebAssembly.
-- Some but not all of the packages attempt to santize sensitive data,
-  however this is not done consistently through the library at the moment.
-  As Thomas Pornin puts it "In general, such memory cleansing is a fool's
-  quest."
+- The packages attempt to santize sensitive data, however this is, and
+  will remain a "best-effort" implementation decision.  As Thomas Pornin
+  puts it "In general, such memory cleansing is a fool's quest."
 - All of these packages have not received independent third party review.
 
 ## License
diff --git a/core/crypto/_blake2/blake2.odin b/core/crypto/_blake2/blake2.odin
index 13b58dba9..2ad74843b 100644
--- a/core/crypto/_blake2/blake2.odin
+++ b/core/crypto/_blake2/blake2.odin
@@ -11,6 +11,7 @@ package _blake2
 */
 
 import "core:encoding/endian"
+import "core:mem"
 
 BLAKE2S_BLOCK_SIZE :: 64
 BLAKE2S_SIZE :: 32
@@ -28,7 +29,6 @@ Blake2s_Context :: struct {
 	is_keyed:     bool,
 	size:         byte,
 	is_last_node: bool,
-	cfg:          Blake2_Config,
 
 	is_initialized: bool,
 }
@@ -44,7 +44,6 @@ Blake2b_Context :: struct {
 	is_keyed:     bool,
 	size:         byte,
 	is_last_node: bool,
-	cfg:          Blake2_Config,
 
 	is_initialized: bool,
 }
@@ -83,62 +82,61 @@ BLAKE2B_IV := [8]u64 {
 	0x1f83d9abfb41bd6b, 0x5be0cd19137e2179,
 }
 
-init :: proc(ctx: ^$T) {
+init :: proc(ctx: ^$T, cfg: ^Blake2_Config) {
 	when T == Blake2s_Context {
-		block_size :: BLAKE2S_BLOCK_SIZE
 		max_size :: BLAKE2S_SIZE
 	} else when T == Blake2b_Context {
-		block_size :: BLAKE2B_BLOCK_SIZE
 		max_size :: BLAKE2B_SIZE
 	}
 
-	if ctx.cfg.size > max_size {
+	if cfg.size > max_size {
 		panic("blake2: requested output size exceeeds algorithm max")
 	}
 
-	p := make([]byte, block_size)
-	defer delete(p)
+	// To save having to allocate a scratch buffer, use the internal
+	// data buffer (`ctx.x`), as it is exactly the correct size.
+	p := ctx.x[:]
 
-	p[0] = ctx.cfg.size
-	p[1] = byte(len(ctx.cfg.key))
+	p[0] = cfg.size
+	p[1] = byte(len(cfg.key))
 
-	if ctx.cfg.salt != nil {
+	if cfg.salt != nil {
 		when T == Blake2s_Context {
-			copy(p[16:], ctx.cfg.salt)
+			copy(p[16:], cfg.salt)
 		} else when T == Blake2b_Context {
-			copy(p[32:], ctx.cfg.salt)
+			copy(p[32:], cfg.salt)
 		}
 	}
-	if ctx.cfg.person != nil {
+	if cfg.person != nil {
 		when T == Blake2s_Context {
-			copy(p[24:], ctx.cfg.person)
+			copy(p[24:], cfg.person)
 		} else when T == Blake2b_Context {
-			copy(p[48:], ctx.cfg.person)
+			copy(p[48:], cfg.person)
 		}
 	}
 
-	if ctx.cfg.tree != nil {
-		p[2] = ctx.cfg.tree.(Blake2_Tree).fanout
-		p[3] = ctx.cfg.tree.(Blake2_Tree).max_depth
-		endian.unchecked_put_u32le(p[4:], ctx.cfg.tree.(Blake2_Tree).leaf_size)
+	if cfg.tree != nil {
+		p[2] = cfg.tree.(Blake2_Tree).fanout
+		p[3] = cfg.tree.(Blake2_Tree).max_depth
+		endian.unchecked_put_u32le(p[4:], cfg.tree.(Blake2_Tree).leaf_size)
 		when T == Blake2s_Context {
-			p[8] = byte(ctx.cfg.tree.(Blake2_Tree).node_offset)
-			p[9] = byte(ctx.cfg.tree.(Blake2_Tree).node_offset >> 8)
-			p[10] = byte(ctx.cfg.tree.(Blake2_Tree).node_offset >> 16)
-			p[11] = byte(ctx.cfg.tree.(Blake2_Tree).node_offset >> 24)
-			p[12] = byte(ctx.cfg.tree.(Blake2_Tree).node_offset >> 32)
-			p[13] = byte(ctx.cfg.tree.(Blake2_Tree).node_offset >> 40)
-			p[14] = ctx.cfg.tree.(Blake2_Tree).node_depth
-			p[15] = ctx.cfg.tree.(Blake2_Tree).inner_hash_size
+			p[8] = byte(cfg.tree.(Blake2_Tree).node_offset)
+			p[9] = byte(cfg.tree.(Blake2_Tree).node_offset >> 8)
+			p[10] = byte(cfg.tree.(Blake2_Tree).node_offset >> 16)
+			p[11] = byte(cfg.tree.(Blake2_Tree).node_offset >> 24)
+			p[12] = byte(cfg.tree.(Blake2_Tree).node_offset >> 32)
+			p[13] = byte(cfg.tree.(Blake2_Tree).node_offset >> 40)
+			p[14] = cfg.tree.(Blake2_Tree).node_depth
+			p[15] = cfg.tree.(Blake2_Tree).inner_hash_size
 		} else when T == Blake2b_Context {
-			endian.unchecked_put_u64le(p[8:], ctx.cfg.tree.(Blake2_Tree).node_offset)
-			p[16] = ctx.cfg.tree.(Blake2_Tree).node_depth
-			p[17] = ctx.cfg.tree.(Blake2_Tree).inner_hash_size
+			endian.unchecked_put_u64le(p[8:], cfg.tree.(Blake2_Tree).node_offset)
+			p[16] = cfg.tree.(Blake2_Tree).node_depth
+			p[17] = cfg.tree.(Blake2_Tree).inner_hash_size
 		}
 	} else {
 		p[2], p[3] = 1, 1
 	}
-	ctx.size = ctx.cfg.size
+	ctx.size = cfg.size
 	for i := 0; i < 8; i += 1 {
 		when T == Blake2s_Context {
 			ctx.h[i] = BLAKE2S_IV[i] ~ endian.unchecked_get_u32le(p[i * 4:])
@@ -147,11 +145,14 @@ init :: proc(ctx: ^$T) {
 			ctx.h[i] = BLAKE2B_IV[i] ~ endian.unchecked_get_u64le(p[i * 8:])
 		}
 	}
-	if ctx.cfg.tree != nil && ctx.cfg.tree.(Blake2_Tree).is_last_node {
+
+	mem.zero(&ctx.x, size_of(ctx.x)) // Done with the scratch space, no barrier.
+
+	if cfg.tree != nil && cfg.tree.(Blake2_Tree).is_last_node {
 		ctx.is_last_node = true
 	}
-	if len(ctx.cfg.key) > 0 {
-		copy(ctx.padded_key[:], ctx.cfg.key)
+	if len(cfg.key) > 0 {
+		copy(ctx.padded_key[:], cfg.key)
 		update(ctx, ctx.padded_key[:])
 		ctx.is_keyed = true
 	}
@@ -194,22 +195,40 @@ update :: proc(ctx: ^$T, p: []byte) {
 	ctx.nx += copy(ctx.x[ctx.nx:], p)
 }
 
-final :: proc(ctx: ^$T, hash: []byte) {
+final :: proc(ctx: ^$T, hash: []byte, finalize_clone: bool = false) {
 	assert(ctx.is_initialized)
 
+	ctx := ctx
+	if finalize_clone {
+		tmp_ctx: T
+		clone(&tmp_ctx, ctx)
+		ctx = &tmp_ctx
+	}
+	defer(reset(ctx))
+
 	when T == Blake2s_Context {
-		if len(hash) < int(ctx.cfg.size) {
+		if len(hash) < int(ctx.size) {
 			panic("crypto/blake2s: invalid destination digest size")
 		}
 		blake2s_final(ctx, hash)
 	} else when T == Blake2b_Context {
-		if len(hash) < int(ctx.cfg.size) {
+		if len(hash) < int(ctx.size) {
 			panic("crypto/blake2b: invalid destination digest size")
 		}
 		blake2b_final(ctx, hash)
 	}
+}
+
+clone :: proc(ctx, other: ^$T) {
+	ctx^ = other^
+}
+
+reset :: proc(ctx: ^$T) {
+	if !ctx.is_initialized {
+		return
+	}
 
-	ctx.is_initialized = false
+	mem.zero_explicit(ctx, size_of(ctx^))
 }
 
 @(private)
diff --git a/core/crypto/_sha3/sha3.odin b/core/crypto/_sha3/sha3.odin
index 43af0ad75..6779c9770 100644
--- a/core/crypto/_sha3/sha3.odin
+++ b/core/crypto/_sha3/sha3.odin
@@ -12,10 +12,16 @@ package _sha3
 */
 
 import "core:math/bits"
+import "core:mem"
 
 ROUNDS :: 24
 
-Sha3_Context :: struct {
+RATE_224 :: 1152 / 8
+RATE_256 :: 1088 / 8
+RATE_384 :: 832 / 8
+RATE_512 :: 576 / 8
+
+Context :: struct {
 	st:        struct #raw_union {
 		b: [200]u8,
 		q: [25]u64,
@@ -103,81 +109,100 @@ keccakf :: proc "contextless" (st: ^[25]u64) {
 	}
 }
 
-init :: proc(c: ^Sha3_Context) {
+init :: proc(ctx: ^Context) {
 	for i := 0; i < 25; i += 1 {
-		c.st.q[i] = 0
+		ctx.st.q[i] = 0
 	}
-	c.rsiz = 200 - 2 * c.mdlen
-	c.pt = 0
+	ctx.rsiz = 200 - 2 * ctx.mdlen
+	ctx.pt = 0
 
-	c.is_initialized = true
-	c.is_finalized = false
+	ctx.is_initialized = true
+	ctx.is_finalized = false
 }
 
-update :: proc(c: ^Sha3_Context, data: []byte) {
-	assert(c.is_initialized)
-	assert(!c.is_finalized)
+update :: proc(ctx: ^Context, data: []byte) {
+	assert(ctx.is_initialized)
+	assert(!ctx.is_finalized)
 
-	j := c.pt
+	j := ctx.pt
 	for i := 0; i < len(data); i += 1 {
-		c.st.b[j] ~= data[i]
+		ctx.st.b[j] ~= data[i]
 		j += 1
-		if j >= c.rsiz {
-			keccakf(&c.st.q)
+		if j >= ctx.rsiz {
+			keccakf(&ctx.st.q)
 			j = 0
 		}
 	}
-	c.pt = j
+	ctx.pt = j
 }
 
-final :: proc(c: ^Sha3_Context, hash: []byte) {
-	assert(c.is_initialized)
+final :: proc(ctx: ^Context, hash: []byte, finalize_clone: bool = false) {
+	assert(ctx.is_initialized)
 
-	if len(hash) < c.mdlen {
-		if c.is_keccak {
+	if len(hash) < ctx.mdlen {
+		if ctx.is_keccak {
 			panic("crypto/keccac: invalid destination digest size")
 		}
 		panic("crypto/sha3: invalid destination digest size")
 	}
-	if c.is_keccak {
-		c.st.b[c.pt] ~= 0x01
+
+	ctx := ctx
+	if finalize_clone {
+		tmp_ctx: Context
+		clone(&tmp_ctx, ctx)
+		ctx = &tmp_ctx
+	}
+	defer(reset(ctx))
+
+	if ctx.is_keccak {
+		ctx.st.b[ctx.pt] ~= 0x01
 	} else {
-		c.st.b[c.pt] ~= 0x06
+		ctx.st.b[ctx.pt] ~= 0x06
 	}
 
-	c.st.b[c.rsiz - 1] ~= 0x80
-	keccakf(&c.st.q)
-	for i := 0; i < c.mdlen; i += 1 {
-		hash[i] = c.st.b[i]
+	ctx.st.b[ctx.rsiz - 1] ~= 0x80
+	keccakf(&ctx.st.q)
+	for i := 0; i < ctx.mdlen; i += 1 {
+		hash[i] = ctx.st.b[i]
+	}
+}
+
+clone :: proc(ctx, other: ^Context) {
+	ctx^ = other^
+}
+
+reset :: proc(ctx: ^Context) {
+	if !ctx.is_initialized {
+		return
 	}
 
-	c.is_initialized = false // No more absorb, no more squeeze.
+	mem.zero_explicit(ctx, size_of(ctx^))
 }
 
-shake_xof :: proc(c: ^Sha3_Context) {
-	assert(c.is_initialized)
-	assert(!c.is_finalized)
+shake_xof :: proc(ctx: ^Context) {
+	assert(ctx.is_initialized)
+	assert(!ctx.is_finalized)
 
-	c.st.b[c.pt] ~= 0x1F
-	c.st.b[c.rsiz - 1] ~= 0x80
-	keccakf(&c.st.q)
-	c.pt = 0
+	ctx.st.b[ctx.pt] ~= 0x1F
+	ctx.st.b[ctx.rsiz - 1] ~= 0x80
+	keccakf(&ctx.st.q)
+	ctx.pt = 0
 
-	c.is_finalized = true // No more absorb, unlimited squeeze.
+	ctx.is_finalized = true // No more absorb, unlimited squeeze.
 }
 
-shake_out :: proc(c: ^Sha3_Context, hash: []byte) {
-	assert(c.is_initialized)
-	assert(c.is_finalized)
+shake_out :: proc(ctx: ^Context, hash: []byte) {
+	assert(ctx.is_initialized)
+	assert(ctx.is_finalized)
 
-	j := c.pt
+	j := ctx.pt
 	for i := 0; i < len(hash); i += 1 {
-		if j >= c.rsiz {
-			keccakf(&c.st.q)
+		if j >= ctx.rsiz {
+			keccakf(&ctx.st.q)
 			j = 0
 		}
-		hash[i] = c.st.b[j]
+		hash[i] = ctx.st.b[j]
 		j += 1
 	}
-	c.pt = j
+	ctx.pt = j
 }
diff --git a/core/crypto/blake2b/blake2b.odin b/core/crypto/blake2b/blake2b.odin
index 17657311e..384c2ffea 100644
--- a/core/crypto/blake2b/blake2b.odin
+++ b/core/crypto/blake2b/blake2b.odin
@@ -1,3 +1,10 @@
+/*
+package blake2b implements the BLAKE2b hash algorithm.
+
+See:
+- https://datatracker.ietf.org/doc/html/rfc7693
+- https://www.blake2.net
+*/
 package blake2b
 
 /*
@@ -6,122 +13,47 @@ package blake2b
 
     List of contributors:
         zhibog, dotbmp:  Initial implementation.
-
-    Interface for the BLAKE2b hashing algorithm.
-    BLAKE2b and BLAKE2s share the implementation in the _blake2 package.
 */
 
-import "core:io"
-import "core:os"
-
 import "../_blake2"
 
-/*
-    High level API
-*/
-
+// DIGEST_SIZE is the BLAKE2b digest size in bytes.
 DIGEST_SIZE :: 64
 
-// hash_string will hash the given input and return the
-// computed hash
-hash_string :: proc(data: string) -> [DIGEST_SIZE]byte {
-	return hash_bytes(transmute([]byte)(data))
-}
+// BLOCK_SIZE is the BLAKE2b block size in bytes.
+BLOCK_SIZE :: _blake2.BLAKE2B_BLOCK_SIZE
 
-// hash_bytes will hash the given input and return the
-// computed hash
-hash_bytes :: proc(data: []byte) -> [DIGEST_SIZE]byte {
-	hash: [DIGEST_SIZE]byte
-	ctx: Context
-	cfg: _blake2.Blake2_Config
-	cfg.size = _blake2.BLAKE2B_SIZE
-	ctx.cfg = cfg
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash[:])
-	return hash
-}
-
-// hash_string_to_buffer will hash the given input and assign the
-// computed hash to the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_string_to_buffer :: proc(data: string, hash: []byte) {
-	hash_bytes_to_buffer(transmute([]byte)(data), hash)
-}
-
-// hash_bytes_to_buffer will hash the given input and write the
-// computed hash into the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_bytes_to_buffer :: proc(data, hash: []byte) {
-	ctx: Context
-	cfg: _blake2.Blake2_Config
-	cfg.size = _blake2.BLAKE2B_SIZE
-	ctx.cfg = cfg
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash)
-}
+// Context is a BLAKE2b instance.
+Context :: _blake2.Blake2b_Context
 
-// hash_stream will read the stream in chunks and compute a
-// hash from its contents
-hash_stream :: proc(s: io.Stream) -> ([DIGEST_SIZE]byte, bool) {
-	hash: [DIGEST_SIZE]byte
-	ctx: Context
+// init initializes a Context with the default BLAKE2b config.
+init :: proc(ctx: ^Context) {
 	cfg: _blake2.Blake2_Config
 	cfg.size = _blake2.BLAKE2B_SIZE
-	ctx.cfg = cfg
-	init(&ctx)
-
-	buf := make([]byte, 512)
-	defer delete(buf)
-
-	read := 1
-	for read > 0 {
-		read, _ = io.read(s, buf)
-		if read > 0 {
-			update(&ctx, buf[:read])
-		}
-	}
-	final(&ctx, hash[:])
-	return hash, true
+	_blake2.init(ctx, &cfg)
 }
 
-// hash_file will read the file provided by the given handle
-// and compute a hash
-hash_file :: proc(hd: os.Handle, load_at_once := false) -> ([DIGEST_SIZE]byte, bool) {
-	if !load_at_once {
-		return hash_stream(os.stream_from_handle(hd))
-	} else {
-		if buf, ok := os.read_entire_file(hd); ok {
-			return hash_bytes(buf[:]), ok
-		}
-	}
-	return [DIGEST_SIZE]byte{}, false
+// update adds more data to the Context.
+update :: proc(ctx: ^Context, data: []byte) {
+	_blake2.update(ctx, data)
 }
 
-hash :: proc {
-	hash_stream,
-	hash_file,
-	hash_bytes,
-	hash_string,
-	hash_bytes_to_buffer,
-	hash_string_to_buffer,
+// final finalizes the Context, writes the digest to hash, and calls
+// reset on the Context.
+//
+// Iff finalize_clone is set, final will work on a copy of the Context,
+// which is useful for for calculating rolling digests.
+final :: proc(ctx: ^Context, hash: []byte, finalize_clone: bool = false) {
+	_blake2.final(ctx, hash, finalize_clone)
 }
 
-/*
-    Low level API
-*/
-
-Context :: _blake2.Blake2b_Context
-
-init :: proc(ctx: ^Context) {
-	_blake2.init(ctx)
-}
-
-update :: proc(ctx: ^Context, data: []byte) {
-	_blake2.update(ctx, data)
+// clone clones the Context other into ctx.
+clone :: proc(ctx, other: ^Context) {
+	_blake2.clone(ctx, other)
 }
 
-final :: proc(ctx: ^Context, hash: []byte) {
-	_blake2.final(ctx, hash)
+// reset sanitizes the Context.  The Context must be re-initialized to
+// be used again.
+reset :: proc(ctx: ^Context) {
+	_blake2.reset(ctx)
 }
diff --git a/core/crypto/blake2s/blake2s.odin b/core/crypto/blake2s/blake2s.odin
index 2da619bb8..1ba9bef2d 100644
--- a/core/crypto/blake2s/blake2s.odin
+++ b/core/crypto/blake2s/blake2s.odin
@@ -1,3 +1,10 @@
+/*
+package blake2s implements the BLAKE2s hash algorithm.
+
+See:
+- https://datatracker.ietf.org/doc/html/rfc7693
+- https://www.blake2.net/
+*/
 package blake2s
 
 /*
@@ -6,122 +13,47 @@ package blake2s
 
     List of contributors:
         zhibog, dotbmp:  Initial implementation.
-
-    Interface for the BLAKE2s hashing algorithm.
-    BLAKE2s and BLAKE2b share the implementation in the _blake2 package.
 */
 
-import "core:io"
-import "core:os"
-
 import "../_blake2"
 
-/*
-    High level API
-*/
-
+// DIGEST_SIZE is the BLAKE2s digest size in bytes.
 DIGEST_SIZE :: 32
 
-// hash_string will hash the given input and return the
-// computed hash
-hash_string :: proc(data: string) -> [DIGEST_SIZE]byte {
-	return hash_bytes(transmute([]byte)(data))
-}
+// BLOCK_SIZE is the BLAKE2s block size in bytes.
+BLOCK_SIZE :: _blake2.BLAKE2S_BLOCK_SIZE
 
-// hash_bytes will hash the given input and return the
-// computed hash
-hash_bytes :: proc(data: []byte) -> [DIGEST_SIZE]byte {
-	hash: [DIGEST_SIZE]byte
-	ctx: Context
-	cfg: _blake2.Blake2_Config
-	cfg.size = _blake2.BLAKE2S_SIZE
-	ctx.cfg = cfg
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash[:])
-	return hash
-}
-
-// hash_string_to_buffer will hash the given input and assign the
-// computed hash to the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_string_to_buffer :: proc(data: string, hash: []byte) {
-	hash_bytes_to_buffer(transmute([]byte)(data), hash)
-}
-
-// hash_bytes_to_buffer will hash the given input and write the
-// computed hash into the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_bytes_to_buffer :: proc(data, hash: []byte) {
-	ctx: Context
-	cfg: _blake2.Blake2_Config
-	cfg.size = _blake2.BLAKE2S_SIZE
-	ctx.cfg = cfg
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash)
-}
+// Context is a BLAKE2s instance.
+Context :: _blake2.Blake2s_Context
 
-// hash_stream will read the stream in chunks and compute a
-// hash from its contents
-hash_stream :: proc(s: io.Stream) -> ([DIGEST_SIZE]byte, bool) {
-	hash: [DIGEST_SIZE]byte
-	ctx: Context
+// init initializes a Context with the default BLAKE2s config.
+init :: proc(ctx: ^Context) {
 	cfg: _blake2.Blake2_Config
 	cfg.size = _blake2.BLAKE2S_SIZE
-	ctx.cfg = cfg
-	init(&ctx)
-
-	buf := make([]byte, 512)
-	defer delete(buf)
-
-	read := 1
-	for read > 0 {
-		read, _ = io.read(s, buf)
-		if read > 0 {
-			update(&ctx, buf[:read])
-		}
-	}
-	final(&ctx, hash[:])
-	return hash, true
+	_blake2.init(ctx, &cfg)
 }
 
-// hash_file will read the file provided by the given handle
-// and compute a hash
-hash_file :: proc(hd: os.Handle, load_at_once := false) -> ([DIGEST_SIZE]byte, bool) {
-	if !load_at_once {
-		return hash_stream(os.stream_from_handle(hd))
-	} else {
-		if buf, ok := os.read_entire_file(hd); ok {
-			return hash_bytes(buf[:]), ok
-		}
-	}
-	return [DIGEST_SIZE]byte{}, false
+// update adds more data to the Context.
+update :: proc(ctx: ^Context, data: []byte) {
+	_blake2.update(ctx, data)
 }
 
-hash :: proc {
-	hash_stream,
-	hash_file,
-	hash_bytes,
-	hash_string,
-	hash_bytes_to_buffer,
-	hash_string_to_buffer,
+// final finalizes the Context, writes the digest to hash, and calls
+// reset on the Context.
+//
+// Iff finalize_clone is set, final will work on a copy of the Context,
+// which is useful for for calculating rolling digests.
+final :: proc(ctx: ^Context, hash: []byte, finalize_clone: bool = false) {
+	_blake2.final(ctx, hash, finalize_clone)
 }
 
-/*
-    Low level API
-*/
-
-Context :: _blake2.Blake2s_Context
-
-init :: proc(ctx: ^Context) {
-	_blake2.init(ctx)
-}
-
-update :: proc(ctx: ^Context, data: []byte) {
-	_blake2.update(ctx, data)
+// clone clones the Context other into ctx.
+clone :: proc(ctx, other: ^Context) {
+	_blake2.clone(ctx, other)
 }
 
-final :: proc(ctx: ^Context, hash: []byte) {
-	_blake2.final(ctx, hash)
+// reset sanitizes the Context.  The Context must be re-initialized to
+// be used again.
+reset :: proc(ctx: ^Context) {
+	_blake2.reset(ctx)
 }
diff --git a/core/crypto/hash/doc.odin b/core/crypto/hash/doc.odin
new file mode 100644
index 000000000..d50908b94
--- /dev/null
+++ b/core/crypto/hash/doc.odin
@@ -0,0 +1,62 @@
+/*
+package hash provides a generic interface to the supported hash algorithms.
+
+A high-level convenience procedure group `hash` is provided to easily
+accomplish common tasks.
+- `hash_string` - Hash a given string and return the digest.
+- `hash_bytes` - Hash a given byte slice and return the digest.
+- `hash_string_to_buffer` - Hash a given string and put the digest in
+  the third parameter.  It requires that the destination buffer
+  is at least as big as the digest size.
+- `hash_bytes_to_buffer` - Hash a given string and put the computed
+  digest in the third parameter.  It requires that the destination
+  buffer is at least as big as the digest size.
+- `hash_stream` - Incrementally fully consume a `io.Stream`, and return
+  the computed digest.
+- `hash_file` - Takes a file handle and returns the computed digest.
+  A third optional boolean parameter controls if the file is streamed
+  (default), or or read at once.
+
+```odin
+package hash_example
+
+import "core:crypto/hash"
+
+main :: proc() {
+	input := "Feed the fire."
+
+	// Compute the digest, using the high level API.
+	returned_digest := hash.hash(hash.Algorithm.SHA512_256, input)
+	defer delete(returned_digest)
+
+	// Variant that takes a destination buffer, instead of returning
+	// the digest.
+	digest := make([]byte, hash.DIGEST_SIZES[hash.Algorithm.BLAKE2B]) // @note: Destination buffer has to be at least as big as the digest size of the hash.
+	defer delete(digest)
+	hash.hash(hash.Algorithm.BLAKE2B, input, digest)
+}
+```
+
+A generic low level API is provided supporting the init/update/final interface
+that is typical with cryptographic hash function implementations.
+
+```odin
+package hash_example
+
+import "core:crypto/hash"
+
+main :: proc() {
+    input := "Let the cinders burn."
+
+    // Compute the digest, using the low level API.
+    ctx: hash.Context
+    digest := make([]byte, hash.DIGEST_SIZES[hash.Algorithm.SHA3_512])
+    defer delete(digest)
+
+    hash.init(&ctx, hash.Algorithm.SHA3_512)
+    hash.update(&ctx, transmute([]byte)input)
+    hash.final(&ctx, digest)
+}
+```
+*/
+package crypto_hash
\ No newline at end of file
diff --git a/core/crypto/hash/hash.odin b/core/crypto/hash/hash.odin
new file mode 100644
index 000000000..e4b3d4be1
--- /dev/null
+++ b/core/crypto/hash/hash.odin
@@ -0,0 +1,116 @@
+package crypto_hash
+
+/*
+    Copyright 2021 zhibog
+    Made available under the BSD-3 license.
+
+    List of contributors:
+        zhibog, dotbmp:  Initial implementation.
+*/
+
+import "core:io"
+import "core:mem"
+import "core:os"
+
+// hash_bytes will hash the given input and return the computed digest
+// in a newly allocated slice.
+hash_string :: proc(algorithm: Algorithm, data: string, allocator := context.allocator) -> []byte {
+	return hash_bytes(algorithm, transmute([]byte)(data), allocator)
+}
+
+// hash_bytes will hash the given input and return the computed digest
+// in a newly allocated slice.
+hash_bytes :: proc(algorithm: Algorithm, data: []byte, allocator := context.allocator) -> []byte {
+	dst := make([]byte, DIGEST_SIZES[algorithm], allocator)
+	hash_bytes_to_buffer(algorithm, data, dst)
+	return dst
+}
+
+// hash_string_to_buffer will hash the given input and assign the
+// computed digest to the third parameter.  It requires that the
+// destination buffer is at least as big as the digest size.
+hash_string_to_buffer :: proc(algorithm: Algorithm, data: string, hash: []byte) {
+	hash_bytes_to_buffer(algorithm, transmute([]byte)(data), hash)
+}
+
+// hash_bytes_to_buffer will hash the given input and write the
+// computed digest into the third parameter.  It requires that the
+// destination buffer is at least as big as the digest size.
+hash_bytes_to_buffer :: proc(algorithm: Algorithm, data, hash: []byte) {
+	ctx: Context
+
+	init(&ctx, algorithm)
+	update(&ctx, data)
+	final(&ctx, hash)
+}
+
+// hash_stream will incrementally fully consume a stream, and return the
+// computed digest in a newly allocated slice.
+hash_stream :: proc(
+	algorithm: Algorithm,
+	s: io.Stream,
+	allocator := context.allocator,
+) -> (
+	[]byte,
+	io.Error,
+) {
+	ctx: Context
+
+	buf: [MAX_BLOCK_SIZE * 4]byte
+	defer mem.zero_explicit(&buf, size_of(buf))
+
+	init(&ctx, algorithm)
+
+	loop: for {
+		n, err := io.read(s, buf[:])
+		if n > 0 {
+			// XXX/yawning: Can io.read return n > 0 and EOF?
+			update(&ctx, buf[:n])
+		}
+		#partial switch err {
+		case .None:
+		case .EOF:
+			break loop
+		case:
+			return nil, err
+		}
+	}
+
+	dst := make([]byte, DIGEST_SIZES[algorithm], allocator)
+	final(&ctx, dst)
+
+	return dst, io.Error.None
+}
+
+// hash_file will read the file provided by the given handle and return the
+// computed digest in a newly allocated slice.
+hash_file :: proc(
+	algorithm: Algorithm,
+	hd: os.Handle,
+	load_at_once := false,
+	allocator := context.allocator,
+) -> (
+	[]byte,
+	io.Error,
+) {
+	if !load_at_once {
+		return hash_stream(algorithm, os.stream_from_handle(hd), allocator)
+	}
+
+	buf, ok := os.read_entire_file(hd, allocator)
+	if !ok {
+		return nil, io.Error.Unknown
+	}
+	defer delete(buf, allocator)
+
+	return hash_bytes(algorithm, buf, allocator), io.Error.None
+}
+
+hash :: proc {
+	hash_stream,
+	hash_file,
+	hash_bytes,
+	hash_string,
+	hash_bytes_to_buffer,
+	hash_string_to_buffer,
+}
diff --git a/core/crypto/hash/low_level.odin b/core/crypto/hash/low_level.odin
new file mode 100644
index 000000000..242eadd5f
--- /dev/null
+++ b/core/crypto/hash/low_level.odin
@@ -0,0 +1,353 @@
+package crypto_hash
+
+import "core:crypto/blake2b"
+import "core:crypto/blake2s"
+import "core:crypto/sha2"
+import "core:crypto/sha3"
+import "core:crypto/sm3"
+import "core:crypto/legacy/keccak"
+import "core:crypto/legacy/md5"
+import "core:crypto/legacy/sha1"
+
+import "core:reflect"
+
+// MAX_DIGEST_SIZE is the maximum size digest that can be returned by any
+// of the Algorithms supported via this package.
+MAX_DIGEST_SIZE :: 64
+// MAX_BLOCK_SIZE is the maximum block size used by any of Algorithms
+// supported by this package.
+MAX_BLOCK_SIZE :: sha3.BLOCK_SIZE_224
+
+// Algorithm is the algorithm identifier associated with a given Context.
+Algorithm :: enum {
+	Invalid,
+	BLAKE2B,
+	BLAKE2S,
+	SHA224,
+	SHA256,
+	SHA384,
+	SHA512,
+	SHA512_256,
+	SHA3_224,
+	SHA3_256,
+	SHA3_384,
+	SHA3_512,
+	SM3,
+	Legacy_KECCAK_224,
+	Legacy_KECCAK_256,
+	Legacy_KECCAK_384,
+	Legacy_KECCAK_512,
+	Insecure_MD5,
+	Insecure_SHA1,
+}
+
+// ALGORITHM_NAMES is the Algorithm to algorithm name string.
+ALGORITHM_NAMES := [Algorithm]string {
+	.Invalid           = "Invalid",
+	.BLAKE2B           = "BLAKE2b",
+	.BLAKE2S           = "BLAKE2s",
+	.SHA224            = "SHA-224",
+	.SHA256            = "SHA-256",
+	.SHA384            = "SHA-384",
+	.SHA512            = "SHA-512",
+	.SHA512_256        = "SHA-512/256",
+	.SHA3_224          = "SHA3-224",
+	.SHA3_256          = "SHA3-256",
+	.SHA3_384          = "SHA3-384",
+	.SHA3_512          = "SHA3-512",
+	.SM3               = "SM3",
+	.Legacy_KECCAK_224 = "Keccak-224",
+	.Legacy_KECCAK_256 = "Keccak-256",
+	.Legacy_KECCAK_384 = "Keccak-384",
+	.Legacy_KECCAK_512 = "Keccak-512",
+	.Insecure_MD5      = "MD5",
+	.Insecure_SHA1     = "SHA-1",
+}
+
+// DIGEST_SIZES is the Algorithm to digest size in bytes.
+DIGEST_SIZES := [Algorithm]int {
+	.Invalid           = 0,
+	.BLAKE2B           = blake2b.DIGEST_SIZE,
+	.BLAKE2S           = blake2s.DIGEST_SIZE,
+	.SHA224            = sha2.DIGEST_SIZE_224,
+	.SHA256            = sha2.DIGEST_SIZE_256,
+	.SHA384            = sha2.DIGEST_SIZE_384,
+	.SHA512            = sha2.DIGEST_SIZE_512,
+	.SHA512_256        = sha2.DIGEST_SIZE_512_256,
+	.SHA3_224          = sha3.DIGEST_SIZE_224,
+	.SHA3_256          = sha3.DIGEST_SIZE_256,
+	.SHA3_384          = sha3.DIGEST_SIZE_384,
+	.SHA3_512          = sha3.DIGEST_SIZE_512,
+	.SM3               = sm3.DIGEST_SIZE,
+	.Legacy_KECCAK_224 = keccak.DIGEST_SIZE_224,
+	.Legacy_KECCAK_256 = keccak.DIGEST_SIZE_256,
+	.Legacy_KECCAK_384 = keccak.DIGEST_SIZE_384,
+	.Legacy_KECCAK_512 = keccak.DIGEST_SIZE_512,
+	.Insecure_MD5      = md5.DIGEST_SIZE,
+	.Insecure_SHA1     = sha1.DIGEST_SIZE,
+}
+
+// BLOCK_SIZES is the Algoritm to block size in bytes.
+BLOCK_SIZES := [Algorithm]int {
+	.Invalid           = 0,
+	.BLAKE2B           = blake2b.BLOCK_SIZE,
+	.BLAKE2S           = blake2s.BLOCK_SIZE,
+	.SHA224            = sha2.BLOCK_SIZE_256,
+	.SHA256            = sha2.BLOCK_SIZE_256,
+	.SHA384            = sha2.BLOCK_SIZE_512,
+	.SHA512            = sha2.BLOCK_SIZE_512,
+	.SHA512_256        = sha2.BLOCK_SIZE_512,
+	.SHA3_224          = sha3.BLOCK_SIZE_224,
+	.SHA3_256          = sha3.BLOCK_SIZE_256,
+	.SHA3_384          = sha3.BLOCK_SIZE_384,
+	.SHA3_512          = sha3.BLOCK_SIZE_512,
+	.SM3               = sm3.BLOCK_SIZE,
+	.Legacy_KECCAK_224 = keccak.BLOCK_SIZE_224,
+	.Legacy_KECCAK_256 = keccak.BLOCK_SIZE_256,
+	.Legacy_KECCAK_384 = keccak.BLOCK_SIZE_384,
+	.Legacy_KECCAK_512 = keccak.BLOCK_SIZE_512,
+	.Insecure_MD5      = md5.BLOCK_SIZE,
+	.Insecure_SHA1     = sha1.BLOCK_SIZE,
+}
+
+// Context is a concrete instantiation of a specific hash algorithm.
+Context :: struct {
+	_algo: Algorithm,
+	_impl: union {
+		blake2b.Context,
+		blake2s.Context,
+		sha2.Context_256,
+		sha2.Context_512,
+		sha3.Context,
+		sm3.Context,
+		keccak.Context,
+		md5.Context,
+		sha1.Context,
+	},
+}
+
+@(private)
+_IMPL_IDS := [Algorithm]typeid {
+	.Invalid           = nil,
+	.BLAKE2B           = typeid_of(blake2b.Context),
+	.BLAKE2S           = typeid_of(blake2s.Context),
+	.SHA224            = typeid_of(sha2.Context_256),
+	.SHA256            = typeid_of(sha2.Context_256),
+	.SHA384            = typeid_of(sha2.Context_512),
+	.SHA512            = typeid_of(sha2.Context_512),
+	.SHA512_256        = typeid_of(sha2.Context_512),
+	.SHA3_224          = typeid_of(sha3.Context),
+	.SHA3_256          = typeid_of(sha3.Context),
+	.SHA3_384          = typeid_of(sha3.Context),
+	.SHA3_512          = typeid_of(sha3.Context),
+	.SM3               = typeid_of(sm3.Context),
+	.Legacy_KECCAK_224 = typeid_of(keccak.Context),
+	.Legacy_KECCAK_256 = typeid_of(keccak.Context),
+	.Legacy_KECCAK_384 = typeid_of(keccak.Context),
+	.Legacy_KECCAK_512 = typeid_of(keccak.Context),
+	.Insecure_MD5      = typeid_of(md5.Context),
+	.Insecure_SHA1     = typeid_of(sha1.Context),
+}
+
+// init initializes a Context with a specific hash Algorithm.
+init :: proc(ctx: ^Context, algorithm: Algorithm) {
+	if ctx._impl != nil {
+		reset(ctx)
+	}
+
+	// Directly specialize the union by setting the type ID (save a copy).
+	reflect.set_union_variant_typeid(
+		ctx._impl,
+		_IMPL_IDS[algorithm],
+	)
+	switch algorithm {
+	case .BLAKE2B:
+		blake2b.init(&ctx._impl.(blake2b.Context))
+	case .BLAKE2S:
+		blake2s.init(&ctx._impl.(blake2s.Context))
+	case .SHA224:
+		sha2.init_224(&ctx._impl.(sha2.Context_256))
+	case .SHA256:
+		sha2.init_256(&ctx._impl.(sha2.Context_256))
+	case .SHA384:
+		sha2.init_384(&ctx._impl.(sha2.Context_512))
+	case .SHA512:
+		sha2.init_512(&ctx._impl.(sha2.Context_512))
+	case .SHA512_256:
+		sha2.init_512_256(&ctx._impl.(sha2.Context_512))
+	case .SHA3_224:
+		sha3.init_224(&ctx._impl.(sha3.Context))
+	case .SHA3_256:
+		sha3.init_256(&ctx._impl.(sha3.Context))
+	case .SHA3_384:
+		sha3.init_384(&ctx._impl.(sha3.Context))
+	case .SHA3_512:
+		sha3.init_512(&ctx._impl.(sha3.Context))
+	case .SM3:
+		sm3.init(&ctx._impl.(sm3.Context))
+	case .Legacy_KECCAK_224:
+		keccak.init_224(&ctx._impl.(keccak.Context))
+	case .Legacy_KECCAK_256:
+		keccak.init_256(&ctx._impl.(keccak.Context))
+	case .Legacy_KECCAK_384:
+		keccak.init_384(&ctx._impl.(keccak.Context))
+	case .Legacy_KECCAK_512:
+		keccak.init_512(&ctx._impl.(keccak.Context))
+	case .Insecure_MD5:
+		md5.init(&ctx._impl.(md5.Context))
+	case .Insecure_SHA1:
+		sha1.init(&ctx._impl.(sha1.Context))
+	case .Invalid:
+		panic("crypto/hash: uninitialized algorithm")
+	case:
+		panic("crypto/hash: invalid algorithm")
+	}
+
+	ctx._algo = algorithm
+}
+
+// update adds more data to the Context.
+update :: proc(ctx: ^Context, data: []byte) {
+	switch &impl in ctx._impl {
+	case blake2b.Context:
+		blake2b.update(&impl, data)
+	case blake2s.Context:
+		blake2s.update(&impl, data)
+	case sha2.Context_256:
+		sha2.update(&impl, data)
+	case sha2.Context_512:
+		sha2.update(&impl, data)
+	case sha3.Context:
+		sha3.update(&impl, data)
+	case sm3.Context:
+		sm3.update(&impl, data)
+	case keccak.Context:
+		keccak.update(&impl, data)
+	case md5.Context:
+		md5.update(&impl, data)
+	case sha1.Context:
+		sha1.update(&impl, data)
+	case:
+		panic("crypto/hash: uninitialized algorithm")
+	}
+}
+
+// final finalizes the Context, writes the digest to hash, and calls
+// reset on the Context.
+//
+// Iff finalize_clone is set, final will work on a copy of the Context,
+// which is useful for for calculating rolling digests.
+final :: proc(ctx: ^Context, hash: []byte, finalize_clone: bool = false) {
+	switch &impl in ctx._impl {
+	case blake2b.Context:
+		blake2b.final(&impl, hash, finalize_clone)
+	case blake2s.Context:
+		blake2s.final(&impl, hash, finalize_clone)
+	case sha2.Context_256:
+		sha2.final(&impl, hash, finalize_clone)
+	case sha2.Context_512:
+		sha2.final(&impl, hash, finalize_clone)
+	case sha3.Context:
+		sha3.final(&impl, hash, finalize_clone)
+	case sm3.Context:
+		sm3.final(&impl, hash, finalize_clone)
+	case keccak.Context:
+		keccak.final(&impl, hash, finalize_clone)
+	case md5.Context:
+		md5.final(&impl, hash, finalize_clone)
+	case sha1.Context:
+		sha1.final(&impl, hash, finalize_clone)
+	case:
+		panic("crypto/hash: uninitialized algorithm")
+	}
+
+	if !finalize_clone {
+		reset(ctx)
+	}
+}
+
+// clone clones the Context other into ctx.
+clone :: proc(ctx, other: ^Context) {
+	// XXX/yawning: Maybe these cases should panic, because both cases,
+	// are probably bugs.
+	if ctx == other {
+		return
+	}
+	if ctx._impl != nil {
+		reset(ctx)
+	}
+
+	ctx._algo = other._algo
+
+	reflect.set_union_variant_typeid(
+		ctx._impl,
+		reflect.union_variant_typeid(other._impl),
+	)
+	switch &src_impl in other._impl {
+	case blake2b.Context:
+		blake2b.clone(&ctx._impl.(blake2b.Context), &src_impl)
+	case blake2s.Context:
+		blake2s.clone(&ctx._impl.(blake2s.Context), &src_impl)
+	case sha2.Context_256:
+		sha2.clone(&ctx._impl.(sha2.Context_256), &src_impl)
+	case sha2.Context_512:
+		sha2.clone(&ctx._impl.(sha2.Context_512), &src_impl)
+	case sha3.Context:
+		sha3.clone(&ctx._impl.(sha3.Context), &src_impl)
+	case sm3.Context:
+		sm3.clone(&ctx._impl.(sm3.Context), &src_impl)
+	case keccak.Context:
+		keccak.clone(&ctx._impl.(keccak.Context), &src_impl)
+	case md5.Context:
+		md5.clone(&ctx._impl.(md5.Context), &src_impl)
+	case sha1.Context:
+		sha1.clone(&ctx._impl.(sha1.Context), &src_impl)
+	case:
+		panic("crypto/hash: uninitialized algorithm")
+	}
+}
+
+// reset sanitizes the Context.  The Context must be re-initialized to
+// be used again.
+reset :: proc(ctx: ^Context) {
+	switch &impl in ctx._impl {
+	case blake2b.Context:
+		blake2b.reset(&impl)
+	case blake2s.Context:
+		blake2s.reset(&impl)
+	case sha2.Context_256:
+		sha2.reset(&impl)
+	case sha2.Context_512:
+		sha2.reset(&impl)
+	case sha3.Context:
+		sha3.reset(&impl)
+	case sm3.Context:
+		sm3.reset(&impl)
+	case keccak.Context:
+		keccak.reset(&impl)
+	case md5.Context:
+		md5.reset(&impl)
+	case sha1.Context:
+		sha1.reset(&impl)
+	case:
+	// Unlike clone, calling reset repeatedly is fine.
+	}
+
+	ctx._algo = .Invalid
+	ctx._impl = nil
+}
+
+// algorithm returns the Algorithm used by a Context instance.
+algorithm :: proc(ctx: ^Context) -> Algorithm {
+	return ctx._algo
+}
+
+// digest_size returns the digest size of a Context instance in bytes.
+digest_size :: proc(ctx: ^Context) -> int {
+	return DIGEST_SIZES[ctx._algo]
+}
+
+// block_size returns the block size of a Context instance in bytes.
+block_size :: proc(ctx: ^Context) -> int {
+	return BLOCK_SIZES[ctx._algo]
+}
diff --git a/core/crypto/hmac/hmac.odin b/core/crypto/hmac/hmac.odin
new file mode 100644
index 000000000..f720d2181
--- /dev/null
+++ b/core/crypto/hmac/hmac.odin
@@ -0,0 +1,162 @@
+/*
+package hmac implements the HMAC MAC algorithm.
+
+See:
+- https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.198-1.pdf
+*/
+package hmac
+
+import "core:crypto"
+import "core:crypto/hash"
+import "core:mem"
+
+// sum will compute the HMAC with the specified algorithm and key
+// over msg, and write the computed digest to dst.  It requires that
+// the dst buffer is the tag size.
+sum :: proc(algorithm: hash.Algorithm, dst, msg, key: []byte) {
+	ctx: Context
+
+	init(&ctx, algorithm, key)
+	update(&ctx, msg)
+	final(&ctx, dst)
+}
+
+// verify will verify the HMAC tag computed with the specified algorithm
+// and key over msg and return true iff the tag is valid.  It requires
+// that the tag is correctly sized.
+verify :: proc(algorithm: hash.Algorithm, tag, msg, key: []byte) -> bool {
+	tag_buf: [hash.MAX_DIGEST_SIZE]byte
+
+	derived_tag := tag_buf[:hash.DIGEST_SIZES[algorithm]]
+	sum(algorithm, derived_tag, msg, key)
+
+	return crypto.compare_constant_time(derived_tag, tag) == 1
+}
+
+// Context is a concrete instantiation of HMAC with a specific hash
+// algorithm.
+Context :: struct {
+	_o_hash:         hash.Context, // H(k ^ ipad) (not finalized)
+	_i_hash:         hash.Context, // H(k ^ opad) (not finalized)
+	_tag_sz:         int,
+	_is_initialized: bool,
+}
+
+// init initializes a Context with a specific hash Algorithm and key.
+init :: proc(ctx: ^Context, algorithm: hash.Algorithm, key: []byte) {
+	if ctx._is_initialized {
+		reset(ctx)
+	}
+
+	_init_hashes(ctx, algorithm, key)
+
+	ctx._tag_sz = hash.DIGEST_SIZES[algorithm]
+	ctx._is_initialized = true
+}
+
+// update adds more data to the Context.
+update :: proc(ctx: ^Context, data: []byte) {
+	assert(ctx._is_initialized)
+
+	hash.update(&ctx._i_hash, data)
+}
+
+// final finalizes the Context, writes the tag to dst, and calls
+// reset on the Context.
+final :: proc(ctx: ^Context, dst: []byte) {
+	assert(ctx._is_initialized)
+
+	defer (reset(ctx))
+
+	if len(dst) != ctx._tag_sz {
+		panic("crypto/hmac: invalid destination tag size")
+	}
+
+	hash.final(&ctx._i_hash, dst) // H((k ^ ipad) || text)
+
+	hash.update(&ctx._o_hash, dst) // H((k ^ opad) || H((k ^ ipad) || text))
+	hash.final(&ctx._o_hash, dst)
+}
+
+// reset sanitizes the Context.  The Context must be re-initialized to
+// be used again.
+reset :: proc(ctx: ^Context) {
+	if !ctx._is_initialized {
+		return
+	}
+
+	hash.reset(&ctx._o_hash)
+	hash.reset(&ctx._i_hash)
+	ctx._tag_sz = 0
+	ctx._is_initialized = false
+}
+
+// algorithm returns the Algorithm used by a Context instance.
+algorithm :: proc(ctx: ^Context) -> hash.Algorithm {
+	assert(ctx._is_initialized)
+
+	return hash.algorithm(&ctx._i_hash)
+}
+
+// tag_size returns the tag size of a Context instance in bytes.
+tag_size :: proc(ctx: ^Context) -> int {
+	assert(ctx._is_initialized)
+
+	return ctx._tag_sz
+}
+
+@(private)
+_I_PAD :: 0x36
+_O_PAD :: 0x5c
+
+@(private)
+_init_hashes :: proc(ctx: ^Context, algorithm: hash.Algorithm, key: []byte) {
+	K0_buf: [hash.MAX_BLOCK_SIZE]byte
+	kPad_buf: [hash.MAX_BLOCK_SIZE]byte
+
+	kLen := len(key)
+	B := hash.BLOCK_SIZES[algorithm]
+	K0 := K0_buf[:B]
+	defer mem.zero_explicit(raw_data(K0), B)
+
+	switch {
+	case kLen == B, kLen < B:
+		// If the length of K = B: set K0 = K.
+		//
+		// If the length of K < B: append zeros to the end of K to
+		// create a B-byte string K0 (e.g., if K is 20 bytes in
+		// length and B = 64, then K will be appended with 44 zero
+		// bytes x’00’).
+		//
+		// K0 is zero-initialized, so the copy handles both cases.
+		copy(K0, key)
+	case kLen > B:
+		// If the length of K > B: hash K to obtain an L byte string,
+		// then append (B-L) zeros to create a B-byte string K0
+		// (i.e., K0 = H(K) || 00...00).
+		tmpCtx := &ctx._o_hash // Saves allocating a hash.Context.
+		hash.init(tmpCtx, algorithm)
+		hash.update(tmpCtx, key)
+		hash.final(tmpCtx, K0)
+	}
+
+	// Initialize the hashes, and write the padded keys:
+	// - ctx._i_hash -> H(K0 ^ ipad)
+	// - ctx._o_hash -> H(K0 ^ opad)
+
+	hash.init(&ctx._o_hash, algorithm)
+	hash.init(&ctx._i_hash, algorithm)
+
+	kPad := kPad_buf[:B]
+	defer mem.zero_explicit(raw_data(kPad), B)
+
+	for v, i in K0 {
+		kPad[i] = v ~ _I_PAD
+	}
+	hash.update(&ctx._i_hash, kPad)
+
+	for v, i in K0 {
+		kPad[i] = v ~ _O_PAD
+	}
+	hash.update(&ctx._o_hash, kPad)
+}
diff --git a/core/crypto/legacy/keccak/keccak.odin b/core/crypto/legacy/keccak/keccak.odin
index 09db853a6..00ad06ad9 100644
--- a/core/crypto/legacy/keccak/keccak.odin
+++ b/core/crypto/legacy/keccak/keccak.odin
@@ -1,3 +1,11 @@
+/*
+package keccak implements the Keccak hash algorithm family.
+
+During the SHA-3 standardization process, the padding scheme was changed
+thus Keccac and SHA-3 produce different outputs.  Most users should use
+SHA-3 and/or SHAKE instead, however the legacy algorithm is provided for
+backward compatibility purposes.
+*/
 package keccak
 
 /*
@@ -6,372 +14,82 @@ package keccak
 
     List of contributors:
         zhibog, dotbmp:  Initial implementation.
-
-    Interface for the Keccak hashing algorithm.
-    This is done because the padding in the SHA3 standard was changed by the NIST, resulting in a different output.
 */
 
-import "core:io"
-import "core:os"
-
 import "../../_sha3"
 
-/*
-    High level API
-*/
-
+// DIGEST_SIZE_224 is the Keccak-224 digest size.
 DIGEST_SIZE_224 :: 28
+// DIGEST_SIZE_256 is the Keccak-256 digest size.
 DIGEST_SIZE_256 :: 32
+// DIGEST_SIZE_384 is the Keccak-384 digest size.
 DIGEST_SIZE_384 :: 48
+// DIGEST_SIZE_512 is the Keccak-512 digest size.
 DIGEST_SIZE_512 :: 64
 
-// hash_string_224 will hash the given input and return the
-// computed hash
-hash_string_224 :: proc(data: string) -> [DIGEST_SIZE_224]byte {
-	return hash_bytes_224(transmute([]byte)(data))
-}
+// BLOCK_SIZE_224 is the Keccak-224 block size in bytes.
+BLOCK_SIZE_224 :: _sha3.RATE_224
+// BLOCK_SIZE_256 is the Keccak-256 block size in bytes.
+BLOCK_SIZE_256 :: _sha3.RATE_256
+// BLOCK_SIZE_384 is the Keccak-384 block size in bytes.
+BLOCK_SIZE_384 :: _sha3.RATE_384
+// BLOCK_SIZE_512 is the Keccak-512 block size in bytes.
+BLOCK_SIZE_512 :: _sha3.RATE_512
 
-// hash_bytes_224 will hash the given input and return the
-// computed hash
-hash_bytes_224 :: proc(data: []byte) -> [DIGEST_SIZE_224]byte {
-	hash: [DIGEST_SIZE_224]byte
-	ctx: Context
-	ctx.mdlen = DIGEST_SIZE_224
-	ctx.is_keccak = true
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash[:])
-	return hash
-}
-
-// hash_string_to_buffer_224 will hash the given input and assign the
-// computed hash to the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_string_to_buffer_224 :: proc(data: string, hash: []byte) {
-	hash_bytes_to_buffer_224(transmute([]byte)(data), hash)
-}
-
-// hash_bytes_to_buffer_224 will hash the given input and write the
-// computed hash into the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_bytes_to_buffer_224 :: proc(data, hash: []byte) {
-	ctx: Context
-	ctx.mdlen = DIGEST_SIZE_224
-	ctx.is_keccak = true
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash)
-}
+// Context is a Keccak instance.
+Context :: distinct _sha3.Context
 
-// hash_stream_224 will read the stream in chunks and compute a
-// hash from its contents
-hash_stream_224 :: proc(s: io.Stream) -> ([DIGEST_SIZE_224]byte, bool) {
-	hash: [DIGEST_SIZE_224]byte
-	ctx: Context
+// init_224 initializes a Context for Keccak-224.
+init_224 :: proc(ctx: ^Context) {
 	ctx.mdlen = DIGEST_SIZE_224
-	ctx.is_keccak = true
-	init(&ctx)
-
-	buf := make([]byte, 512)
-	defer delete(buf)
-
-	read := 1
-	for read > 0 {
-		read, _ = io.read(s, buf)
-		if read > 0 {
-			update(&ctx, buf[:read])
-		}
-	}
-	final(&ctx, hash[:])
-	return hash, true
+	_init(ctx)
 }
 
-// hash_file_224 will read the file provided by the given handle
-// and compute a hash
-hash_file_224 :: proc(hd: os.Handle, load_at_once := false) -> ([DIGEST_SIZE_224]byte, bool) {
-	if !load_at_once {
-		return hash_stream_224(os.stream_from_handle(hd))
-	} else {
-		if buf, ok := os.read_entire_file(hd); ok {
-			return hash_bytes_224(buf[:]), ok
-		}
-	}
-	return [DIGEST_SIZE_224]byte{}, false
-}
-
-hash_224 :: proc {
-	hash_stream_224,
-	hash_file_224,
-	hash_bytes_224,
-	hash_string_224,
-	hash_bytes_to_buffer_224,
-	hash_string_to_buffer_224,
-}
-
-// hash_string_256 will hash the given input and return the
-// computed hash
-hash_string_256 :: proc(data: string) -> [DIGEST_SIZE_256]byte {
-	return hash_bytes_256(transmute([]byte)(data))
-}
-
-// hash_bytes_256 will hash the given input and return the
-// computed hash
-hash_bytes_256 :: proc(data: []byte) -> [DIGEST_SIZE_256]byte {
-	hash: [DIGEST_SIZE_256]byte
-	ctx: Context
+// init_256 initializes a Context for Keccak-256.
+init_256 :: proc(ctx: ^Context) {
 	ctx.mdlen = DIGEST_SIZE_256
-	ctx.is_keccak = true
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash[:])
-	return hash
-}
-
-// hash_string_to_buffer_256 will hash the given input and assign the
-// computed hash to the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_string_to_buffer_256 :: proc(data: string, hash: []byte) {
-	hash_bytes_to_buffer_256(transmute([]byte)(data), hash)
-}
-
-// hash_bytes_to_buffer_256 will hash the given input and write the
-// computed hash into the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_bytes_to_buffer_256 :: proc(data, hash: []byte) {
-	ctx: Context
-	ctx.mdlen = DIGEST_SIZE_256
-	ctx.is_keccak = true
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash)
-}
-
-// hash_stream_256 will read the stream in chunks and compute a
-// hash from its contents
-hash_stream_256 :: proc(s: io.Stream) -> ([DIGEST_SIZE_256]byte, bool) {
-	hash: [DIGEST_SIZE_256]byte
-	ctx: Context
-	ctx.mdlen = DIGEST_SIZE_256
-	ctx.is_keccak = true
-	init(&ctx)
-
-	buf := make([]byte, 512)
-	defer delete(buf)
-
-	read := 1
-	for read > 0 {
-		read, _ = io.read(s, buf)
-		if read > 0 {
-			update(&ctx, buf[:read])
-		}
-	}
-	final(&ctx, hash[:])
-	return hash, true
-}
-
-// hash_file_256 will read the file provided by the given handle
-// and compute a hash
-hash_file_256 :: proc(hd: os.Handle, load_at_once := false) -> ([DIGEST_SIZE_256]byte, bool) {
-	if !load_at_once {
-		return hash_stream_256(os.stream_from_handle(hd))
-	} else {
-		if buf, ok := os.read_entire_file(hd); ok {
-			return hash_bytes_256(buf[:]), ok
-		}
-	}
-	return [DIGEST_SIZE_256]byte{}, false
+	_init(ctx)
 }
 
-hash_256 :: proc {
-	hash_stream_256,
-	hash_file_256,
-	hash_bytes_256,
-	hash_string_256,
-	hash_bytes_to_buffer_256,
-	hash_string_to_buffer_256,
-}
-
-// hash_string_384 will hash the given input and return the
-// computed hash
-hash_string_384 :: proc(data: string) -> [DIGEST_SIZE_384]byte {
-	return hash_bytes_384(transmute([]byte)(data))
-}
-
-// hash_bytes_384 will hash the given input and return the
-// computed hash
-hash_bytes_384 :: proc(data: []byte) -> [DIGEST_SIZE_384]byte {
-	hash: [DIGEST_SIZE_384]byte
-	ctx: Context
+// init_384 initializes a Context for Keccak-384.
+init_384 :: proc(ctx: ^Context) {
 	ctx.mdlen = DIGEST_SIZE_384
-	ctx.is_keccak = true
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash[:])
-	return hash
-}
-
-// hash_string_to_buffer_384 will hash the given input and assign the
-// computed hash to the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_string_to_buffer_384 :: proc(data: string, hash: []byte) {
-	hash_bytes_to_buffer_384(transmute([]byte)(data), hash)
-}
-
-// hash_bytes_to_buffer_384 will hash the given input and write the
-// computed hash into the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_bytes_to_buffer_384 :: proc(data, hash: []byte) {
-	ctx: Context
-	ctx.mdlen = DIGEST_SIZE_384
-	ctx.is_keccak = true
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash)
-}
-
-// hash_stream_384 will read the stream in chunks and compute a
-// hash from its contents
-hash_stream_384 :: proc(s: io.Stream) -> ([DIGEST_SIZE_384]byte, bool) {
-	hash: [DIGEST_SIZE_384]byte
-	ctx: Context
-	ctx.mdlen = DIGEST_SIZE_384
-	ctx.is_keccak = true
-	init(&ctx)
-
-	buf := make([]byte, 512)
-	defer delete(buf)
-
-	read := 1
-	for read > 0 {
-		read, _ = io.read(s, buf)
-		if read > 0 {
-			update(&ctx, buf[:read])
-		}
-	}
-	final(&ctx, hash[:])
-	return hash, true
-}
-
-// hash_file_384 will read the file provided by the given handle
-// and compute a hash
-hash_file_384 :: proc(hd: os.Handle, load_at_once := false) -> ([DIGEST_SIZE_384]byte, bool) {
-	if !load_at_once {
-		return hash_stream_384(os.stream_from_handle(hd))
-	} else {
-		if buf, ok := os.read_entire_file(hd); ok {
-			return hash_bytes_384(buf[:]), ok
-		}
-	}
-	return [DIGEST_SIZE_384]byte{}, false
-}
-
-hash_384 :: proc {
-	hash_stream_384,
-	hash_file_384,
-	hash_bytes_384,
-	hash_string_384,
-	hash_bytes_to_buffer_384,
-	hash_string_to_buffer_384,
+	_init(ctx)
 }
 
-// hash_string_512 will hash the given input and return the
-// computed hash
-hash_string_512 :: proc(data: string) -> [DIGEST_SIZE_512]byte {
-	return hash_bytes_512(transmute([]byte)(data))
-}
-
-// hash_bytes_512 will hash the given input and return the
-// computed hash
-hash_bytes_512 :: proc(data: []byte) -> [DIGEST_SIZE_512]byte {
-	hash: [DIGEST_SIZE_512]byte
-	ctx: Context
+// init_512 initializes a Context for Keccak-512.
+init_512 :: proc(ctx: ^Context) {
 	ctx.mdlen = DIGEST_SIZE_512
-	ctx.is_keccak = true
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash[:])
-	return hash
+	_init(ctx)
 }
 
-// hash_string_to_buffer_512 will hash the given input and assign the
-// computed hash to the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_string_to_buffer_512 :: proc(data: string, hash: []byte) {
-	hash_bytes_to_buffer_512(transmute([]byte)(data), hash)
-}
-
-// hash_bytes_to_buffer_512 will hash the given input and write the
-// computed hash into the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_bytes_to_buffer_512 :: proc(data, hash: []byte) {
-	ctx: Context
-	ctx.mdlen = DIGEST_SIZE_512
+@(private)
+_init :: proc(ctx: ^Context) {
 	ctx.is_keccak = true
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash)
+	_sha3.init(transmute(^_sha3.Context)(ctx))
 }
 
-// hash_stream_512 will read the stream in chunks and compute a
-// hash from its contents
-hash_stream_512 :: proc(s: io.Stream) -> ([DIGEST_SIZE_512]byte, bool) {
-	hash: [DIGEST_SIZE_512]byte
-	ctx: Context
-	ctx.mdlen = DIGEST_SIZE_512
-	ctx.is_keccak = true
-	init(&ctx)
-
-	buf := make([]byte, 512)
-	defer delete(buf)
-
-	read := 1
-	for read > 0 {
-		read, _ = io.read(s, buf)
-		if read > 0 {
-			update(&ctx, buf[:read])
-		}
-	}
-	final(&ctx, hash[:])
-	return hash, true
-}
-
-// hash_file_512 will read the file provided by the given handle
-// and compute a hash
-hash_file_512 :: proc(hd: os.Handle, load_at_once := false) -> ([DIGEST_SIZE_512]byte, bool) {
-	if !load_at_once {
-		return hash_stream_512(os.stream_from_handle(hd))
-	} else {
-		if buf, ok := os.read_entire_file(hd); ok {
-			return hash_bytes_512(buf[:]), ok
-		}
-	}
-	return [DIGEST_SIZE_512]byte{}, false
-}
-
-hash_512 :: proc {
-	hash_stream_512,
-	hash_file_512,
-	hash_bytes_512,
-	hash_string_512,
-	hash_bytes_to_buffer_512,
-	hash_string_to_buffer_512,
+// update adds more data to the Context.
+update :: proc(ctx: ^Context, data: []byte) {
+	_sha3.update(transmute(^_sha3.Context)(ctx), data)
 }
 
-/*
-    Low level API
-*/
-
-Context :: _sha3.Sha3_Context
-
-init :: proc(ctx: ^Context) {
-	ctx.is_keccak = true
-	_sha3.init(ctx)
+// final finalizes the Context, writes the digest to hash, and calls
+// reset on the Context.
+//
+// Iff finalize_clone is set, final will work on a copy of the Context,
+// which is useful for for calculating rolling digests.
+final :: proc(ctx: ^Context, hash: []byte, finalize_clone: bool = false) {
+	_sha3.final(transmute(^_sha3.Context)(ctx), hash, finalize_clone)
 }
 
-update :: proc(ctx: ^Context, data: []byte) {
-	_sha3.update(ctx, data)
+// clone clones the Context other into ctx.
+clone :: proc(ctx, other: ^Context) {
+	_sha3.clone(transmute(^_sha3.Context)(ctx), transmute(^_sha3.Context)(other))
 }
 
-final :: proc(ctx: ^Context, hash: []byte) {
-	_sha3.final(ctx, hash)
+// reset sanitizes the Context.  The Context must be re-initialized to
+// be used again.
+reset :: proc(ctx: ^Context) {
+	_sha3.reset(transmute(^_sha3.Context)(ctx))
 }
diff --git a/core/crypto/legacy/md5/md5.odin b/core/crypto/legacy/md5/md5.odin
index 69ae087e4..c744a9bcf 100644
--- a/core/crypto/legacy/md5/md5.odin
+++ b/core/crypto/legacy/md5/md5.odin
@@ -1,3 +1,13 @@
+/*
+package md5 implements the MD5 hash algorithm.
+
+WARNING: The MD5 algorithm is known to be insecure and should only be
+used for interoperating with legacy applications.
+
+See:
+- https://eprint.iacr.org/2005/075
+- https://datatracker.ietf.org/doc/html/rfc1321
+*/
 package md5
 
 /*
@@ -6,103 +16,29 @@ package md5
 
     List of contributors:
         zhibog, dotbmp:  Initial implementation.
-
-    Implementation of the MD5 hashing algorithm, as defined in RFC 1321 <https://datatracker.ietf.org/doc/html/rfc1321>
 */
 
 import "core:encoding/endian"
-import "core:io"
 import "core:math/bits"
 import "core:mem"
-import "core:os"
-
-/*
-    High level API
-*/
 
+// DIGEST_SIZE is the MD5 digest size in bytes.
 DIGEST_SIZE :: 16
 
-// hash_string will hash the given input and return the
-// computed hash
-hash_string :: proc(data: string) -> [DIGEST_SIZE]byte {
-	return hash_bytes(transmute([]byte)(data))
-}
-
-// hash_bytes will hash the given input and return the
-// computed hash
-hash_bytes :: proc(data: []byte) -> [DIGEST_SIZE]byte {
-	hash: [DIGEST_SIZE]byte
-	ctx: Context
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash[:])
-	return hash
-}
-
-// hash_string_to_buffer will hash the given input and assign the
-// computed hash to the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_string_to_buffer :: proc(data: string, hash: []byte) {
-	hash_bytes_to_buffer(transmute([]byte)(data), hash)
-}
-
-// hash_bytes_to_buffer will hash the given input and write the
-// computed hash into the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_bytes_to_buffer :: proc(data, hash: []byte) {
-	ctx: Context
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash)
-}
-
-// hash_stream will read the stream in chunks and compute a
-// hash from its contents
-hash_stream :: proc(s: io.Stream) -> ([DIGEST_SIZE]byte, bool) {
-	hash: [DIGEST_SIZE]byte
-	ctx: Context
-	init(&ctx)
-
-	buf := make([]byte, 512)
-	defer delete(buf)
-
-	read := 1
-	for read > 0 {
-		read, _ = io.read(s, buf)
-		if read > 0 {
-			update(&ctx, buf[:read])
-		}
-	}
-	final(&ctx, hash[:])
-	return hash, true
-}
+// BLOCK_SIZE is the MD5 block size in bytes.
+BLOCK_SIZE :: 64
 
-// hash_file will read the file provided by the given handle
-// and compute a hash
-hash_file :: proc(hd: os.Handle, load_at_once := false) -> ([DIGEST_SIZE]byte, bool) {
-	if !load_at_once {
-		return hash_stream(os.stream_from_handle(hd))
-	} else {
-		if buf, ok := os.read_entire_file(hd); ok {
-			return hash_bytes(buf[:]), ok
-		}
-	}
-	return [DIGEST_SIZE]byte{}, false
-}
+// Context is a MD5 instance.
+Context :: struct {
+	data:    [BLOCK_SIZE]byte,
+	state:   [4]u32,
+	bitlen:  u64,
+	datalen: u32,
 
-hash :: proc {
-	hash_stream,
-	hash_file,
-	hash_bytes,
-	hash_string,
-	hash_bytes_to_buffer,
-	hash_string_to_buffer,
+	is_initialized: bool,
 }
 
-/*
-    Low level API
-*/
-
+// init initializes a Context.
 init :: proc(ctx: ^Context) {
 	ctx.state[0] = 0x67452301
 	ctx.state[1] = 0xefcdab89
@@ -115,6 +51,7 @@ init :: proc(ctx: ^Context) {
 	ctx.is_initialized = true
 }
 
+// update adds more data to the Context.
 update :: proc(ctx: ^Context, data: []byte) {
 	assert(ctx.is_initialized)
 
@@ -129,13 +66,26 @@ update :: proc(ctx: ^Context, data: []byte) {
 	}
 }
 
-final :: proc(ctx: ^Context, hash: []byte) {
+// final finalizes the Context, writes the digest to hash, and calls
+// reset on the Context.
+//
+// Iff finalize_clone is set, final will work on a copy of the Context,
+// which is useful for for calculating rolling digests.
+final :: proc(ctx: ^Context, hash: []byte, finalize_clone: bool = false) {
 	assert(ctx.is_initialized)
 
 	if len(hash) < DIGEST_SIZE {
 		panic("crypto/md5: invalid destination digest size")
 	}
 
+	ctx := ctx
+	if finalize_clone {
+		tmp_ctx: Context
+		clone(&tmp_ctx, ctx)
+		ctx = &tmp_ctx
+	}
+	defer(reset(ctx))
+
 	i := ctx.datalen
 
 	if ctx.datalen < 56 {
@@ -163,25 +113,27 @@ final :: proc(ctx: ^Context, hash: []byte) {
 	for i = 0; i < DIGEST_SIZE / 4; i += 1 {
 		endian.unchecked_put_u32le(hash[i * 4:], ctx.state[i])
 	}
+}
 
-	ctx.is_initialized = false
+// clone clones the Context other into ctx.
+clone :: proc(ctx, other: ^$T) {
+	ctx^ = other^
+}
+
+// reset sanitizes the Context.  The Context must be re-initialized to
+// be used again.
+reset :: proc(ctx: ^$T) {
+	if !ctx.is_initialized {
+		return
+	}
+
+	mem.zero_explicit(ctx, size_of(ctx^))
 }
 
 /*
     MD5 implementation
 */
 
-BLOCK_SIZE :: 64
-
-Context :: struct {
-	data:    [BLOCK_SIZE]byte,
-	state:   [4]u32,
-	bitlen:  u64,
-	datalen: u32,
-
-	is_initialized: bool,
-}
-
 /*
     @note(zh): F, G, H and I, as mentioned in the RFC, have been inlined into FF, GG, HH
     and II respectively, instead of declaring them separately.
diff --git a/core/crypto/legacy/sha1/sha1.odin b/core/crypto/legacy/sha1/sha1.odin
index 6c4407067..8c6e59901 100644
--- a/core/crypto/legacy/sha1/sha1.odin
+++ b/core/crypto/legacy/sha1/sha1.odin
@@ -1,3 +1,14 @@
+/*
+package sha1 implements the SHA1 hash algorithm.
+
+WARNING: The SHA1 algorithm is known to be insecure and should only be
+used for interoperating with legacy applications.
+
+See:
+- https://eprint.iacr.org/2017/190
+- https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.180-4.pdf
+- https://datatracker.ietf.org/doc/html/rfc3174
+*/
 package sha1
 
 /*
@@ -6,103 +17,30 @@ package sha1
 
     List of contributors:
         zhibog, dotbmp:  Initial implementation.
-
-    Implementation of the SHA1 hashing algorithm, as defined in RFC 3174 <https://datatracker.ietf.org/doc/html/rfc3174>
 */
 
 import "core:encoding/endian"
-import "core:io"
 import "core:math/bits"
 import "core:mem"
-import "core:os"
-
-/*
-    High level API
-*/
 
+// DIGEST_SIZE is the SHA1 digest size in bytes.
 DIGEST_SIZE :: 20
 
-// hash_string will hash the given input and return the
-// computed hash
-hash_string :: proc(data: string) -> [DIGEST_SIZE]byte {
-	return hash_bytes(transmute([]byte)(data))
-}
-
-// hash_bytes will hash the given input and return the
-// computed hash
-hash_bytes :: proc(data: []byte) -> [DIGEST_SIZE]byte {
-	hash: [DIGEST_SIZE]byte
-	ctx: Context
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash[:])
-	return hash
-}
-
-// hash_string_to_buffer will hash the given input and assign the
-// computed hash to the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_string_to_buffer :: proc(data: string, hash: []byte) {
-	hash_bytes_to_buffer(transmute([]byte)(data), hash)
-}
-
-// hash_bytes_to_buffer will hash the given input and write the
-// computed hash into the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_bytes_to_buffer :: proc(data, hash: []byte) {
-	ctx: Context
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash)
-}
-
-// hash_stream will read the stream in chunks and compute a
-// hash from its contents
-hash_stream :: proc(s: io.Stream) -> ([DIGEST_SIZE]byte, bool) {
-	hash: [DIGEST_SIZE]byte
-	ctx: Context
-	init(&ctx)
-
-	buf := make([]byte, 512)
-	defer delete(buf)
-
-	read := 1
-	for read > 0 {
-		read, _ = io.read(s, buf)
-		if read > 0 {
-			update(&ctx, buf[:read])
-		}
-	}
-	final(&ctx, hash[:])
-	return hash, true
-}
+// BLOCK_SIZE is the SHA1 block size in bytes.
+BLOCK_SIZE :: 64
 
-// hash_file will read the file provided by the given handle
-// and compute a hash
-hash_file :: proc(hd: os.Handle, load_at_once := false) -> ([DIGEST_SIZE]byte, bool) {
-	if !load_at_once {
-		return hash_stream(os.stream_from_handle(hd))
-	} else {
-		if buf, ok := os.read_entire_file(hd); ok {
-			return hash_bytes(buf[:]), ok
-		}
-	}
-	return [DIGEST_SIZE]byte{}, false
-}
+// Context is a SHA1 instance.
+Context :: struct {
+	data:    [BLOCK_SIZE]byte,
+	state:   [5]u32,
+	k:       [4]u32,
+	bitlen:  u64,
+	datalen: u32,
 
-hash :: proc {
-	hash_stream,
-	hash_file,
-	hash_bytes,
-	hash_string,
-	hash_bytes_to_buffer,
-	hash_string_to_buffer,
+	is_initialized: bool,
 }
 
-/*
-    Low level API
-*/
-
+// init initializes a Context.
 init :: proc(ctx: ^Context) {
 	ctx.state[0] = 0x67452301
 	ctx.state[1] = 0xefcdab89
@@ -120,6 +58,7 @@ init :: proc(ctx: ^Context) {
 	ctx.is_initialized = true
 }
 
+// update adds more data to the Context.
 update :: proc(ctx: ^Context, data: []byte) {
 	assert(ctx.is_initialized)
 
@@ -134,13 +73,26 @@ update :: proc(ctx: ^Context, data: []byte) {
 	}
 }
 
-final :: proc(ctx: ^Context, hash: []byte) {
+// final finalizes the Context, writes the digest to hash, and calls
+// reset on the Context.
+//
+// Iff finalize_clone is set, final will work on a copy of the Context,
+// which is useful for for calculating rolling digests.
+final :: proc(ctx: ^Context, hash: []byte, finalize_clone: bool = false) {
 	assert(ctx.is_initialized)
 
 	if len(hash) < DIGEST_SIZE {
 		panic("crypto/sha1: invalid destination digest size")
 	}
 
+	ctx := ctx
+	if finalize_clone {
+		tmp_ctx: Context
+		clone(&tmp_ctx, ctx)
+		ctx = &tmp_ctx
+	}
+	defer(reset(ctx))
+
 	i := ctx.datalen
 
 	if ctx.datalen < 56 {
@@ -168,26 +120,27 @@ final :: proc(ctx: ^Context, hash: []byte) {
 	for i = 0; i < DIGEST_SIZE / 4; i += 1 {
 		endian.unchecked_put_u32be(hash[i * 4:], ctx.state[i])
 	}
+}
+
+// clone clones the Context other into ctx.
+clone :: proc(ctx, other: ^$T) {
+	ctx^ = other^
+}
+
+// reset sanitizes the Context.  The Context must be re-initialized to
+// be used again.
+reset :: proc(ctx: ^$T) {
+	if !ctx.is_initialized {
+		return
+	}
 
-	ctx.is_initialized = false
+	mem.zero_explicit(ctx, size_of(ctx^))
 }
 
 /*
     SHA1 implementation
 */
 
-BLOCK_SIZE :: 64
-
-Context :: struct {
-	data:    [BLOCK_SIZE]byte,
-	datalen: u32,
-	bitlen:  u64,
-	state:   [5]u32,
-	k:       [4]u32,
-
-	is_initialized: bool,
-}
-
 @(private)
 transform :: proc "contextless" (ctx: ^Context, data: []byte) {
 	a, b, c, d, e, i, t: u32
diff --git a/core/crypto/poly1305/poly1305.odin b/core/crypto/poly1305/poly1305.odin
index cf60f7166..a2fb3c223 100644
--- a/core/crypto/poly1305/poly1305.odin
+++ b/core/crypto/poly1305/poly1305.odin
@@ -23,10 +23,6 @@ verify :: proc (tag, msg, key: []byte) -> bool {
 	ctx: Context = ---
 	derived_tag: [16]byte = ---
 
-	if len(tag) != TAG_SIZE {
-		panic("crypto/poly1305: invalid tag size")
-	}
-
 	init(&ctx, key)
 	update(&ctx, msg)
 	final(&ctx, derived_tag[:])
diff --git a/core/crypto/sha2/sha2.odin b/core/crypto/sha2/sha2.odin
index 10ac73ab6..2128e3950 100644
--- a/core/crypto/sha2/sha2.odin
+++ b/core/crypto/sha2/sha2.odin
@@ -1,3 +1,10 @@
+/*
+package sha2 implements the SHA2 hash algorithm family.
+
+See:
+- https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.180-4.pdf
+- https://datatracker.ietf.org/doc/html/rfc3874
+*/
 package sha2
 
 /*
@@ -6,431 +13,83 @@ package sha2
 
     List of contributors:
         zhibog, dotbmp:  Initial implementation.
-
-    Implementation of the SHA2 hashing algorithm, as defined in <https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.180-4.pdf>
-    and in RFC 3874 <https://datatracker.ietf.org/doc/html/rfc3874>
 */
 
 import "core:encoding/endian"
-import "core:io"
 import "core:math/bits"
-import "core:os"
-
-/*
-    High level API
-*/
+import "core:mem"
 
+// DIGEST_SIZE_224 is the SHA-224 digest size in bytes.
 DIGEST_SIZE_224 :: 28
+// DIGEST_SIZE_256 is the SHA-256 digest size in bytes.
 DIGEST_SIZE_256 :: 32
+// DIGEST_SIZE_384 is the SHA-384 digest size in bytes.
 DIGEST_SIZE_384 :: 48
+// DIGEST_SIZE_512 is the SHA-512 digest size in bytes.
 DIGEST_SIZE_512 :: 64
+// DIGEST_SIZE_512_256 is the SHA-512/256 digest size in bytes.
 DIGEST_SIZE_512_256 :: 32
 
-// hash_string_224 will hash the given input and return the
-// computed hash
-hash_string_224 :: proc(data: string) -> [DIGEST_SIZE_224]byte {
-	return hash_bytes_224(transmute([]byte)(data))
-}
-
-// hash_bytes_224 will hash the given input and return the
-// computed hash
-hash_bytes_224 :: proc(data: []byte) -> [DIGEST_SIZE_224]byte {
-	hash: [DIGEST_SIZE_224]byte
-	ctx: Context_256
-	ctx.md_bits = 224
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash[:])
-	return hash
-}
-
-// hash_string_to_buffer_224 will hash the given input and assign the
-// computed hash to the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_string_to_buffer_224 :: proc(data: string, hash: []byte) {
-	hash_bytes_to_buffer_224(transmute([]byte)(data), hash)
-}
-
-// hash_bytes_to_buffer_224 will hash the given input and write the
-// computed hash into the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_bytes_to_buffer_224 :: proc(data, hash: []byte) {
-	ctx: Context_256
-	ctx.md_bits = 224
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash)
-}
-
-// hash_stream_224 will read the stream in chunks and compute a
-// hash from its contents
-hash_stream_224 :: proc(s: io.Stream) -> ([DIGEST_SIZE_224]byte, bool) {
-	hash: [DIGEST_SIZE_224]byte
-	ctx: Context_256
-	ctx.md_bits = 224
-	init(&ctx)
-
-	buf := make([]byte, 512)
-	defer delete(buf)
+// BLOCK_SIZE_256 is the SHA-224 and SHA-256 block size in bytes.
+BLOCK_SIZE_256 :: 64
+// BLOCK_SIZE_512 is the SHA-384, SHA-512, and SHA-512/256 block size
+// in bytes.
+BLOCK_SIZE_512 :: 128
 
-	read := 1
-	for read > 0 {
-		read, _ = io.read(s, buf)
-		if read > 0 {
-			update(&ctx, buf[:read])
-		}
-	}
-	final(&ctx, hash[:])
-	return hash, true
-}
-
-// hash_file_224 will read the file provided by the given handle
-// and compute a hash
-hash_file_224 :: proc(hd: os.Handle, load_at_once := false) -> ([DIGEST_SIZE_224]byte, bool) {
-	if !load_at_once {
-		return hash_stream_224(os.stream_from_handle(hd))
-	} else {
-		if buf, ok := os.read_entire_file(hd); ok {
-			return hash_bytes_224(buf[:]), ok
-		}
-	}
-	return [DIGEST_SIZE_224]byte{}, false
-}
-
-hash_224 :: proc {
-	hash_stream_224,
-	hash_file_224,
-	hash_bytes_224,
-	hash_string_224,
-	hash_bytes_to_buffer_224,
-	hash_string_to_buffer_224,
-}
+// Context_256 is a SHA-224 or SHA-256 instance.
+Context_256 :: struct {
+	block:     [BLOCK_SIZE_256]byte,
+	h:         [8]u32,
+	bitlength: u64,
+	length:    u64,
+	md_bits:   int,
 
-// hash_string_256 will hash the given input and return the
-// computed hash
-hash_string_256 :: proc(data: string) -> [DIGEST_SIZE_256]byte {
-	return hash_bytes_256(transmute([]byte)(data))
+	is_initialized: bool,
 }
 
-// hash_bytes_256 will hash the given input and return the
-// computed hash
-hash_bytes_256 :: proc(data: []byte) -> [DIGEST_SIZE_256]byte {
-	hash: [DIGEST_SIZE_256]byte
-	ctx: Context_256
-	ctx.md_bits = 256
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash[:])
-	return hash
-}
+// Context_512 is a SHA-384, SHA-512 or SHA-512/256 instance.
+Context_512 :: struct {
+	block:     [BLOCK_SIZE_512]byte,
+	h:         [8]u64,
+	bitlength: u64,
+	length:    u64,
+	md_bits:   int,
 
-// hash_string_to_buffer_256 will hash the given input and assign the
-// computed hash to the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_string_to_buffer_256 :: proc(data: string, hash: []byte) {
-	hash_bytes_to_buffer_256(transmute([]byte)(data), hash)
+	is_initialized: bool,
 }
 
-// hash_bytes_to_buffer_256 will hash the given input and write the
-// computed hash into the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_bytes_to_buffer_256 :: proc(data, hash: []byte) {
-	ctx: Context_256
-	ctx.md_bits = 256
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash)
+// init_224 initializes a Context_256 for SHA-224.
+init_224 :: proc(ctx: ^Context_256) {
+	ctx.md_bits = 224
+	_init(ctx)
 }
 
-// hash_stream_256 will read the stream in chunks and compute a
-// hash from its contents
-hash_stream_256 :: proc(s: io.Stream) -> ([DIGEST_SIZE_256]byte, bool) {
-	hash: [DIGEST_SIZE_256]byte
-	ctx: Context_256
+// init_256 initializes a Context_256 for SHA-256.
+init_256 :: proc(ctx: ^Context_256) {
 	ctx.md_bits = 256
-	init(&ctx)
-
-	buf := make([]byte, 512)
-	defer delete(buf)
-
-	read := 1
-	for read > 0 {
-		read, _ = io.read(s, buf)
-		if read > 0 {
-			update(&ctx, buf[:read])
-		}
-	}
-	final(&ctx, hash[:])
-	return hash, true
+	_init(ctx)
 }
 
-// hash_file_256 will read the file provided by the given handle
-// and compute a hash
-hash_file_256 :: proc(hd: os.Handle, load_at_once := false) -> ([DIGEST_SIZE_256]byte, bool) {
-	if !load_at_once {
-		return hash_stream_256(os.stream_from_handle(hd))
-	} else {
-		if buf, ok := os.read_entire_file(hd); ok {
-			return hash_bytes_256(buf[:]), ok
-		}
-	}
-	return [DIGEST_SIZE_256]byte{}, false
-}
-
-hash_256 :: proc {
-	hash_stream_256,
-	hash_file_256,
-	hash_bytes_256,
-	hash_string_256,
-	hash_bytes_to_buffer_256,
-	hash_string_to_buffer_256,
-}
-
-// hash_string_384 will hash the given input and return the
-// computed hash
-hash_string_384 :: proc(data: string) -> [DIGEST_SIZE_384]byte {
-	return hash_bytes_384(transmute([]byte)(data))
-}
-
-// hash_bytes_384 will hash the given input and return the
-// computed hash
-hash_bytes_384 :: proc(data: []byte) -> [DIGEST_SIZE_384]byte {
-	hash: [DIGEST_SIZE_384]byte
-	ctx: Context_512
-	ctx.md_bits = 384
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash[:])
-	return hash
-}
-
-// hash_string_to_buffer_384 will hash the given input and assign the
-// computed hash to the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_string_to_buffer_384 :: proc(data: string, hash: []byte) {
-	hash_bytes_to_buffer_384(transmute([]byte)(data), hash)
-}
-
-// hash_bytes_to_buffer_384 will hash the given input and write the
-// computed hash into the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_bytes_to_buffer_384 :: proc(data, hash: []byte) {
-	ctx: Context_512
-	ctx.md_bits = 384
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash)
-}
-
-// hash_stream_384 will read the stream in chunks and compute a
-// hash from its contents
-hash_stream_384 :: proc(s: io.Stream) -> ([DIGEST_SIZE_384]byte, bool) {
-	hash: [DIGEST_SIZE_384]byte
-	ctx: Context_512
+// init_384 initializes a Context_512 for SHA-384.
+init_384 :: proc(ctx: ^Context_512) {
 	ctx.md_bits = 384
-	init(&ctx)
-
-	buf := make([]byte, 512)
-	defer delete(buf)
-
-	read := 1
-	for read > 0 {
-		read, _ = io.read(s, buf)
-		if read > 0 {
-			update(&ctx, buf[:read])
-		}
-	}
-	final(&ctx, hash[:])
-	return hash, true
-}
-
-// hash_file_384 will read the file provided by the given handle
-// and compute a hash
-hash_file_384 :: proc(hd: os.Handle, load_at_once := false) -> ([DIGEST_SIZE_384]byte, bool) {
-	if !load_at_once {
-		return hash_stream_384(os.stream_from_handle(hd))
-	} else {
-		if buf, ok := os.read_entire_file(hd); ok {
-			return hash_bytes_384(buf[:]), ok
-		}
-	}
-	return [DIGEST_SIZE_384]byte{}, false
+	_init(ctx)
 }
 
-hash_384 :: proc {
-	hash_stream_384,
-	hash_file_384,
-	hash_bytes_384,
-	hash_string_384,
-	hash_bytes_to_buffer_384,
-	hash_string_to_buffer_384,
-}
-
-// hash_string_512 will hash the given input and return the
-// computed hash
-hash_string_512 :: proc(data: string) -> [DIGEST_SIZE_512]byte {
-	return hash_bytes_512(transmute([]byte)(data))
-}
-
-// hash_bytes_512 will hash the given input and return the
-// computed hash
-hash_bytes_512 :: proc(data: []byte) -> [DIGEST_SIZE_512]byte {
-	hash: [DIGEST_SIZE_512]byte
-	ctx: Context_512
-	ctx.md_bits = 512
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash[:])
-	return hash
-}
-
-// hash_string_to_buffer_512 will hash the given input and assign the
-// computed hash to the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_string_to_buffer_512 :: proc(data: string, hash: []byte) {
-	hash_bytes_to_buffer_512(transmute([]byte)(data), hash)
-}
-
-// hash_bytes_to_buffer_512 will hash the given input and write the
-// computed hash into the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_bytes_to_buffer_512 :: proc(data, hash: []byte) {
-	ctx: Context_512
+// init_512 initializes a Context_512 for SHA-512.
+init_512 :: proc(ctx: ^Context_512) {
 	ctx.md_bits = 512
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash)
+	_init(ctx)
 }
 
-// hash_stream_512 will read the stream in chunks and compute a
-// hash from its contents
-hash_stream_512 :: proc(s: io.Stream) -> ([DIGEST_SIZE_512]byte, bool) {
-	hash: [DIGEST_SIZE_512]byte
-	ctx: Context_512
-	ctx.md_bits = 512
-	init(&ctx)
-
-	buf := make([]byte, 512)
-	defer delete(buf)
-
-	read := 1
-	for read > 0 {
-		read, _ = io.read(s, buf)
-		if read > 0 {
-			update(&ctx, buf[:read])
-		}
-	}
-	final(&ctx, hash[:])
-	return hash, true
-}
-
-// hash_file_512 will read the file provided by the given handle
-// and compute a hash
-hash_file_512 :: proc(hd: os.Handle, load_at_once := false) -> ([DIGEST_SIZE_512]byte, bool) {
-	if !load_at_once {
-		return hash_stream_512(os.stream_from_handle(hd))
-	} else {
-		if buf, ok := os.read_entire_file(hd); ok {
-			return hash_bytes_512(buf[:]), ok
-		}
-	}
-	return [DIGEST_SIZE_512]byte{}, false
-}
-
-hash_512 :: proc {
-	hash_stream_512,
-	hash_file_512,
-	hash_bytes_512,
-	hash_string_512,
-	hash_bytes_to_buffer_512,
-	hash_string_to_buffer_512,
-}
-
-// hash_string_512_256 will hash the given input and return the
-// computed hash
-hash_string_512_256 :: proc(data: string) -> [DIGEST_SIZE_512_256]byte {
-	return hash_bytes_512_256(transmute([]byte)(data))
-}
-
-// hash_bytes_512_256 will hash the given input and return the
-// computed hash
-hash_bytes_512_256 :: proc(data: []byte) -> [DIGEST_SIZE_512_256]byte {
-	hash: [DIGEST_SIZE_512_256]byte
-	ctx: Context_512
-	ctx.md_bits = 256
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash[:])
-	return hash
-}
-
-// hash_string_to_buffer_512_256 will hash the given input and assign the
-// computed hash to the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_string_to_buffer_512_256 :: proc(data: string, hash: []byte) {
-	hash_bytes_to_buffer_512_256(transmute([]byte)(data), hash)
-}
-
-// hash_bytes_to_buffer_512_256 will hash the given input and write the
-// computed hash into the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_bytes_to_buffer_512_256 :: proc(data, hash: []byte) {
-	ctx: Context_512
-	ctx.md_bits = 256
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash)
-}
-
-// hash_stream_512_256 will read the stream in chunks and compute a
-// hash from its contents
-hash_stream_512_256 :: proc(s: io.Stream) -> ([DIGEST_SIZE_512_256]byte, bool) {
-	hash: [DIGEST_SIZE_512_256]byte
-	ctx: Context_512
+// init_512_256 initializes a Context_512 for SHA-512/256.
+init_512_256 :: proc(ctx: ^Context_512) {
 	ctx.md_bits = 256
-	init(&ctx)
-
-	buf := make([]byte, 512)
-	defer delete(buf)
-
-	read := 1
-	for read > 0 {
-		read, _ = io.read(s, buf)
-		if read > 0 {
-			update(&ctx, buf[:read])
-		}
-	}
-	final(&ctx, hash[:])
-	return hash, true
+	_init(ctx)
 }
 
-// hash_file_512_256 will read the file provided by the given handle
-// and compute a hash
-hash_file_512_256 :: proc(hd: os.Handle, load_at_once := false) -> ([DIGEST_SIZE_512_256]byte, bool) {
-	if !load_at_once {
-		return hash_stream_512_256(os.stream_from_handle(hd))
-	} else {
-		if buf, ok := os.read_entire_file(hd); ok {
-			return hash_bytes_512_256(buf[:]), ok
-		}
-	}
-	return [DIGEST_SIZE_512_256]byte{}, false
-}
-
-hash_512_256 :: proc {
-	hash_stream_512_256,
-	hash_file_512_256,
-	hash_bytes_512_256,
-	hash_string_512_256,
-	hash_bytes_to_buffer_512_256,
-	hash_string_to_buffer_512_256,
-}
-
-/*
-    Low level API
-*/
-
-init :: proc(ctx: ^$T) {
+@(private)
+_init :: proc(ctx: ^$T) {
 	when T == Context_256 {
 		switch ctx.md_bits {
 		case 224:
@@ -497,13 +156,14 @@ init :: proc(ctx: ^$T) {
 	ctx.is_initialized = true
 }
 
+// update adds more data to the Context.
 update :: proc(ctx: ^$T, data: []byte) {
 	assert(ctx.is_initialized)
 
 	when T == Context_256 {
-		CURR_BLOCK_SIZE :: SHA256_BLOCK_SIZE
+		CURR_BLOCK_SIZE :: BLOCK_SIZE_256
 	} else when T == Context_512 {
-		CURR_BLOCK_SIZE :: SHA512_BLOCK_SIZE
+		CURR_BLOCK_SIZE :: BLOCK_SIZE_512
 	}
 
 	data := data
@@ -528,21 +188,34 @@ update :: proc(ctx: ^$T, data: []byte) {
 	}
 }
 
-final :: proc(ctx: ^$T, hash: []byte) {
+// final finalizes the Context, writes the digest to hash, and calls
+// reset on the Context.
+//
+// Iff finalize_clone is set, final will work on a copy of the Context,
+// which is useful for for calculating rolling digests.
+final :: proc(ctx: ^$T, hash: []byte, finalize_clone: bool = false) {
 	assert(ctx.is_initialized)
 
 	if len(hash) * 8 < ctx.md_bits {
 		panic("crypto/sha2: invalid destination digest size")
 	}
 
+	ctx := ctx
+	if finalize_clone {
+		tmp_ctx: T
+		clone(&tmp_ctx, ctx)
+		ctx = &tmp_ctx
+	}
+	defer(reset(ctx))
+
 	length := ctx.length
 
-	raw_pad: [SHA512_BLOCK_SIZE]byte
+	raw_pad: [BLOCK_SIZE_512]byte
 	when T == Context_256 {
-		CURR_BLOCK_SIZE :: SHA256_BLOCK_SIZE
+		CURR_BLOCK_SIZE :: BLOCK_SIZE_256
 		pm_len := 8 // 64-bits for length
 	} else when T == Context_512 {
-		CURR_BLOCK_SIZE :: SHA512_BLOCK_SIZE
+		CURR_BLOCK_SIZE :: BLOCK_SIZE_512
 		pm_len := 16 // 128-bits for length
 	}
 	pad := raw_pad[:CURR_BLOCK_SIZE]
@@ -576,37 +249,27 @@ final :: proc(ctx: ^$T, hash: []byte) {
 			endian.unchecked_put_u64be(hash[i * 8:], ctx.h[i])
 		}
 	}
-
-	ctx.is_initialized = false
 }
 
-/*
-    SHA2 implementation
-*/
-
-SHA256_BLOCK_SIZE :: 64
-SHA512_BLOCK_SIZE :: 128
-
-Context_256 :: struct {
-	block:     [SHA256_BLOCK_SIZE]byte,
-	h:         [8]u32,
-	bitlength: u64,
-	length:    u64,
-	md_bits:   int,
-
-	is_initialized: bool,
+// clone clones the Context other into ctx.
+clone :: proc(ctx, other: ^$T) {
+	ctx^ = other^
 }
 
-Context_512 :: struct {
-	block:     [SHA512_BLOCK_SIZE]byte,
-	h:         [8]u64,
-	bitlength: u64,
-	length:    u64,
-	md_bits:   int,
+// reset sanitizes the Context.  The Context must be re-initialized to
+// be used again.
+reset :: proc(ctx: ^$T) {
+	if !ctx.is_initialized {
+		return
+	}
 
-	is_initialized: bool,
+	mem.zero_explicit(ctx, size_of(ctx^))
 }
 
+/*
+    SHA2 implementation
+*/
+
 @(private)
 sha256_k := [64]u32 {
 	0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
@@ -737,12 +400,12 @@ sha2_transf :: proc "contextless" (ctx: ^$T, data: []byte) {
 		w: [64]u32
 		wv: [8]u32
 		t1, t2: u32
-		CURR_BLOCK_SIZE :: SHA256_BLOCK_SIZE
+		CURR_BLOCK_SIZE :: BLOCK_SIZE_256
 	} else when T == Context_512 {
 		w: [80]u64
 		wv: [8]u64
 		t1, t2: u64
-		CURR_BLOCK_SIZE :: SHA512_BLOCK_SIZE
+		CURR_BLOCK_SIZE :: BLOCK_SIZE_512
 	}
 
 	data := data
diff --git a/core/crypto/sha3/sha3.odin b/core/crypto/sha3/sha3.odin
index f91baad3d..87ff9c9cb 100644
--- a/core/crypto/sha3/sha3.odin
+++ b/core/crypto/sha3/sha3.odin
@@ -1,3 +1,13 @@
+/*
+package sha3 implements the SHA3 hash algorithm family.
+
+The SHAKE XOF can be found in crypto/shake.  While discouraged if the
+pre-standardization Keccak algorithm is required, it can be found in
+crypto/legacy/keccak.
+
+See:
+- https://nvlpubs.nist.gov/nistpubs/fips/nist.fips.202.pdf
+*/
 package sha3
 
 /*
@@ -6,359 +16,81 @@ package sha3
 
     List of contributors:
         zhibog, dotbmp:  Initial implementation.
-
-    Interface for the SHA3 hashing algorithm. The SHAKE functionality can be found in package shake.
-    If you wish to compute a Keccak hash, you can use the keccak package, it will use the original padding.
 */
 
-import "core:io"
-import "core:os"
-
 import "../_sha3"
 
-/*
-    High level API
-*/
-
+// DIGEST_SIZE_224 is the SHA3-224 digest size.
 DIGEST_SIZE_224 :: 28
+// DIGEST_SIZE_256 is the SHA3-256 digest size.
 DIGEST_SIZE_256 :: 32
+// DIGEST_SIZE_384 is the SHA3-384 digest size.
 DIGEST_SIZE_384 :: 48
+// DIGEST_SIZE_512 is the SHA3-512 digest size.
 DIGEST_SIZE_512 :: 64
 
-// hash_string_224 will hash the given input and return the
-// computed hash
-hash_string_224 :: proc(data: string) -> [DIGEST_SIZE_224]byte {
-	return hash_bytes_224(transmute([]byte)(data))
-}
+// BLOCK_SIZE_224 is the SHA3-224 block size in bytes.
+BLOCK_SIZE_224 :: _sha3.RATE_224
+// BLOCK_SIZE_256 is the SHA3-256 block size in bytes.
+BLOCK_SIZE_256 :: _sha3.RATE_256
+// BLOCK_SIZE_384 is the SHA3-384 block size in bytes.
+BLOCK_SIZE_384 :: _sha3.RATE_384
+// BLOCK_SIZE_512 is the SHA3-512 block size in bytes.
+BLOCK_SIZE_512 :: _sha3.RATE_512
 
-// hash_bytes_224 will hash the given input and return the
-// computed hash
-hash_bytes_224 :: proc(data: []byte) -> [DIGEST_SIZE_224]byte {
-	hash: [DIGEST_SIZE_224]byte
-	ctx: Context
-	ctx.mdlen = DIGEST_SIZE_224
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash[:])
-	return hash
-}
+// Context is a SHA3 instance.
+Context :: distinct _sha3.Context
 
-// hash_string_to_buffer_224 will hash the given input and assign the
-// computed hash to the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_string_to_buffer_224 :: proc(data: string, hash: []byte) {
-	hash_bytes_to_buffer_224(transmute([]byte)(data), hash)
-}
-
-// hash_bytes_to_buffer_224 will hash the given input and write the
-// computed hash into the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_bytes_to_buffer_224 :: proc(data, hash: []byte) {
-	ctx: Context
+// init_224 initializes a Context for SHA3-224.
+init_224 :: proc(ctx: ^Context) {
 	ctx.mdlen = DIGEST_SIZE_224
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash)
-}
-
-// hash_stream_224 will read the stream in chunks and compute a
-// hash from its contents
-hash_stream_224 :: proc(s: io.Stream) -> ([DIGEST_SIZE_224]byte, bool) {
-	hash: [DIGEST_SIZE_224]byte
-	ctx: Context
-	ctx.mdlen = DIGEST_SIZE_224
-	init(&ctx)
-
-	buf := make([]byte, 512)
-	defer delete(buf)
-
-	read := 1
-	for read > 0 {
-		read, _ = io.read(s, buf)
-		if read > 0 {
-			update(&ctx, buf[:read])
-		}
-	}
-	final(&ctx, hash[:])
-	return hash, true
+	_init(ctx)
 }
 
-// hash_file_224 will read the file provided by the given handle
-// and compute a hash
-hash_file_224 :: proc(hd: os.Handle, load_at_once := false) -> ([DIGEST_SIZE_224]byte, bool) {
-	if !load_at_once {
-		return hash_stream_224(os.stream_from_handle(hd))
-	} else {
-		if buf, ok := os.read_entire_file(hd); ok {
-			return hash_bytes_224(buf[:]), ok
-		}
-	}
-	return [DIGEST_SIZE_224]byte{}, false
-}
-
-hash_224 :: proc {
-	hash_stream_224,
-	hash_file_224,
-	hash_bytes_224,
-	hash_string_224,
-	hash_bytes_to_buffer_224,
-	hash_string_to_buffer_224,
-}
-
-// hash_string_256 will hash the given input and return the
-// computed hash
-hash_string_256 :: proc(data: string) -> [DIGEST_SIZE_256]byte {
-	return hash_bytes_256(transmute([]byte)(data))
-}
-
-// hash_bytes_256 will hash the given input and return the
-// computed hash
-hash_bytes_256 :: proc(data: []byte) -> [DIGEST_SIZE_256]byte {
-	hash: [DIGEST_SIZE_256]byte
-	ctx: Context
-	ctx.mdlen = DIGEST_SIZE_256
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash[:])
-	return hash
-}
-
-// hash_string_to_buffer_256 will hash the given input and assign the
-// computed hash to the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_string_to_buffer_256 :: proc(data: string, hash: []byte) {
-	hash_bytes_to_buffer_256(transmute([]byte)(data), hash)
-}
-
-// hash_bytes_to_buffer_256 will hash the given input and write the
-// computed hash into the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_bytes_to_buffer_256 :: proc(data, hash: []byte) {
-	ctx: Context
-	ctx.mdlen = DIGEST_SIZE_256
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash)
-}
-
-// hash_stream_256 will read the stream in chunks and compute a
-// hash from its contents
-hash_stream_256 :: proc(s: io.Stream) -> ([DIGEST_SIZE_256]byte, bool) {
-	hash: [DIGEST_SIZE_256]byte
-	ctx: Context
+// init_256 initializes a Context for SHA3-256.
+init_256 :: proc(ctx: ^Context) {
 	ctx.mdlen = DIGEST_SIZE_256
-	init(&ctx)
-
-	buf := make([]byte, 512)
-	defer delete(buf)
-
-	read := 1
-	for read > 0 {
-		read, _ = io.read(s, buf)
-		if read > 0 {
-			update(&ctx, buf[:read])
-		}
-	}
-	final(&ctx, hash[:])
-	return hash, true
-}
-
-// hash_file_256 will read the file provided by the given handle
-// and compute a hash
-hash_file_256 :: proc(hd: os.Handle, load_at_once := false) -> ([DIGEST_SIZE_256]byte, bool) {
-	if !load_at_once {
-		return hash_stream_256(os.stream_from_handle(hd))
-	} else {
-		if buf, ok := os.read_entire_file(hd); ok {
-			return hash_bytes_256(buf[:]), ok
-		}
-	}
-	return [DIGEST_SIZE_256]byte{}, false
+	_init(ctx)
 }
 
-hash_256 :: proc {
-	hash_stream_256,
-	hash_file_256,
-	hash_bytes_256,
-	hash_string_256,
-	hash_bytes_to_buffer_256,
-	hash_string_to_buffer_256,
-}
-
-// hash_string_384 will hash the given input and return the
-// computed hash
-hash_string_384 :: proc(data: string) -> [DIGEST_SIZE_384]byte {
-	return hash_bytes_384(transmute([]byte)(data))
-}
-
-// hash_bytes_384 will hash the given input and return the
-// computed hash
-hash_bytes_384 :: proc(data: []byte) -> [DIGEST_SIZE_384]byte {
-	hash: [DIGEST_SIZE_384]byte
-	ctx: Context
-	ctx.mdlen = DIGEST_SIZE_384
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash[:])
-	return hash
-}
-
-// hash_string_to_buffer_384 will hash the given input and assign the
-// computed hash to the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_string_to_buffer_384 :: proc(data: string, hash: []byte) {
-	hash_bytes_to_buffer_384(transmute([]byte)(data), hash)
-}
-
-// hash_bytes_to_buffer_384 will hash the given input and write the
-// computed hash into the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_bytes_to_buffer_384 :: proc(data, hash: []byte) {
-	ctx: Context
+// init_384 initializes a Context for SHA3-384.
+init_384 :: proc(ctx: ^Context) {
 	ctx.mdlen = DIGEST_SIZE_384
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash)
-}
-
-// hash_stream_384 will read the stream in chunks and compute a
-// hash from its contents
-hash_stream_384 :: proc(s: io.Stream) -> ([DIGEST_SIZE_384]byte, bool) {
-	hash: [DIGEST_SIZE_384]byte
-	ctx: Context
-	ctx.mdlen = DIGEST_SIZE_384
-	init(&ctx)
-
-	buf := make([]byte, 512)
-	defer delete(buf)
-
-	read := 1
-	for read > 0 {
-		read, _ = io.read(s, buf)
-		if read > 0 {
-			update(&ctx, buf[:read])
-		}
-	}
-	final(&ctx, hash[:])
-	return hash, true
-}
-
-// hash_file_384 will read the file provided by the given handle
-// and compute a hash
-hash_file_384 :: proc(hd: os.Handle, load_at_once := false) -> ([DIGEST_SIZE_384]byte, bool) {
-	if !load_at_once {
-		return hash_stream_384(os.stream_from_handle(hd))
-	} else {
-		if buf, ok := os.read_entire_file(hd); ok {
-			return hash_bytes_384(buf[:]), ok
-		}
-	}
-	return [DIGEST_SIZE_384]byte{}, false
-}
-
-hash_384 :: proc {
-	hash_stream_384,
-	hash_file_384,
-	hash_bytes_384,
-	hash_string_384,
-	hash_bytes_to_buffer_384,
-	hash_string_to_buffer_384,
+	_init(ctx)
 }
 
-// hash_string_512 will hash the given input and return the
-// computed hash
-hash_string_512 :: proc(data: string) -> [DIGEST_SIZE_512]byte {
-	return hash_bytes_512(transmute([]byte)(data))
-}
-
-// hash_bytes_512 will hash the given input and return the
-// computed hash
-hash_bytes_512 :: proc(data: []byte) -> [DIGEST_SIZE_512]byte {
-	hash: [DIGEST_SIZE_512]byte
-	ctx: Context
-	ctx.mdlen = DIGEST_SIZE_512
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash[:])
-	return hash
-}
-
-// hash_string_to_buffer_512 will hash the given input and assign the
-// computed hash to the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_string_to_buffer_512 :: proc(data: string, hash: []byte) {
-	hash_bytes_to_buffer_512(transmute([]byte)(data), hash)
-}
-
-// hash_bytes_to_buffer_512 will hash the given input and write the
-// computed hash into the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_bytes_to_buffer_512 :: proc(data, hash: []byte) {
-	ctx: Context
-	ctx.mdlen = DIGEST_SIZE_512
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash)
-}
-
-// hash_stream_512 will read the stream in chunks and compute a
-// hash from its contents
-hash_stream_512 :: proc(s: io.Stream) -> ([DIGEST_SIZE_512]byte, bool) {
-	hash: [DIGEST_SIZE_512]byte
-	ctx: Context
+// init_512 initializes a Context for SHA3-512.
+init_512 :: proc(ctx: ^Context) {
 	ctx.mdlen = DIGEST_SIZE_512
-	init(&ctx)
-
-	buf := make([]byte, 512)
-	defer delete(buf)
-
-	read := 1
-	for read > 0 {
-		read, _ = io.read(s, buf)
-		if read > 0 {
-			update(&ctx, buf[:read])
-		}
-	}
-	final(&ctx, hash[:])
-	return hash, true
+	_init(ctx)
 }
 
-// hash_file_512 will read the file provided by the given handle
-// and compute a hash
-hash_file_512 :: proc(hd: os.Handle, load_at_once := false) -> ([DIGEST_SIZE_512]byte, bool) {
-	if !load_at_once {
-		return hash_stream_512(os.stream_from_handle(hd))
-	} else {
-		if buf, ok := os.read_entire_file(hd); ok {
-			return hash_bytes_512(buf[:]), ok
-		}
-	}
-	return [DIGEST_SIZE_512]byte{}, false
+@(private)
+_init :: proc(ctx: ^Context) {
+	_sha3.init(transmute(^_sha3.Context)(ctx))
 }
 
-hash_512 :: proc {
-	hash_stream_512,
-	hash_file_512,
-	hash_bytes_512,
-	hash_string_512,
-	hash_bytes_to_buffer_512,
-	hash_string_to_buffer_512,
+// update adds more data to the Context.
+update :: proc(ctx: ^Context, data: []byte) {
+	_sha3.update(transmute(^_sha3.Context)(ctx), data)
 }
 
-/*
-    Low level API
-*/
-
-Context :: _sha3.Sha3_Context
-
-init :: proc(ctx: ^Context) {
-	_sha3.init(ctx)
+// final finalizes the Context, writes the digest to hash, and calls
+// reset on the Context.
+//
+// Iff finalize_clone is set, final will work on a copy of the Context,
+// which is useful for for calculating rolling digests.
+final :: proc(ctx: ^Context, hash: []byte, finalize_clone: bool = false) {
+	_sha3.final(transmute(^_sha3.Context)(ctx), hash, finalize_clone)
 }
 
-update :: proc(ctx: ^Context, data: []byte) {
-	_sha3.update(ctx, data)
+// clone clones the Context other into ctx.
+clone :: proc(ctx, other: ^Context) {
+	_sha3.clone(transmute(^_sha3.Context)(ctx), transmute(^_sha3.Context)(other))
 }
 
-final :: proc(ctx: ^Context, hash: []byte) {
-	_sha3.final(ctx, hash)
+// reset sanitizes the Context.  The Context must be re-initialized to
+// be used again.
+reset :: proc(ctx: ^Context) {
+	_sha3.reset(transmute(^_sha3.Context)(ctx))
 }
diff --git a/core/crypto/shake/shake.odin b/core/crypto/shake/shake.odin
index e4b4c1e31..072204800 100644
--- a/core/crypto/shake/shake.odin
+++ b/core/crypto/shake/shake.odin
@@ -1,3 +1,11 @@
+/*
+package shake implements the SHAKE XOF algorithm family.
+
+The SHA3 hash algorithm can be found in the crypto/sha3.
+
+See:
+- https://nvlpubs.nist.gov/nistpubs/fips/nist.fips.202.pdf
+*/
 package shake
 
 /*
@@ -6,201 +14,55 @@ package shake
 
     List of contributors:
         zhibog, dotbmp:  Initial implementation.
-
-    Interface for the SHAKE hashing algorithm.
-    The SHA3 functionality can be found in package sha3.
-
-    TODO: This should provide an incremental squeeze interface, in addition
-    to the one-shot final call.
 */
 
-import "core:io"
-import "core:os"
-
 import "../_sha3"
 
-/*
-    High level API
-*/
-
-DIGEST_SIZE_128 :: 16
-DIGEST_SIZE_256 :: 32
-
-// hash_string_128 will hash the given input and return the
-// computed hash
-hash_string_128 :: proc(data: string) -> [DIGEST_SIZE_128]byte {
-	return hash_bytes_128(transmute([]byte)(data))
-}
-
-// hash_bytes_128 will hash the given input and return the
-// computed hash
-hash_bytes_128 :: proc(data: []byte) -> [DIGEST_SIZE_128]byte {
-	hash: [DIGEST_SIZE_128]byte
-	ctx: Context
-	ctx.mdlen = DIGEST_SIZE_128
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash[:])
-	return hash
-}
-
-// hash_string_to_buffer_128 will hash the given input and assign the
-// computed hash to the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_string_to_buffer_128 :: proc(data: string, hash: []byte) {
-	hash_bytes_to_buffer_128(transmute([]byte)(data), hash)
-}
-
-// hash_bytes_to_buffer_128 will hash the given input and write the
-// computed hash into the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_bytes_to_buffer_128 :: proc(data, hash: []byte) {
-	ctx: Context
-	ctx.mdlen = DIGEST_SIZE_128
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash)
-}
-
-// hash_stream_128 will read the stream in chunks and compute a
-// hash from its contents
-hash_stream_128 :: proc(s: io.Stream) -> ([DIGEST_SIZE_128]byte, bool) {
-	hash: [DIGEST_SIZE_128]byte
-	ctx: Context
-	ctx.mdlen = DIGEST_SIZE_128
-	init(&ctx)
-
-	buf := make([]byte, 512)
-	defer delete(buf)
+// Context is a SHAKE128 or SHAKE256 instance.
+Context :: distinct _sha3.Context
 
-	read := 1
-	for read > 0 {
-		read, _ = io.read(s, buf)
-		if read > 0 {
-			update(&ctx, buf[:read])
-		}
-	}
-	final(&ctx, hash[:])
-	return hash, true
-}
-
-// hash_file_128 will read the file provided by the given handle
-// and compute a hash
-hash_file_128 :: proc(hd: os.Handle, load_at_once := false) -> ([DIGEST_SIZE_128]byte, bool) {
-	if !load_at_once {
-		return hash_stream_128(os.stream_from_handle(hd))
-	} else {
-		if buf, ok := os.read_entire_file(hd); ok {
-			return hash_bytes_128(buf[:]), ok
-		}
-	}
-	return [DIGEST_SIZE_128]byte{}, false
-}
-
-hash_128 :: proc {
-	hash_stream_128,
-	hash_file_128,
-	hash_bytes_128,
-	hash_string_128,
-	hash_bytes_to_buffer_128,
-	hash_string_to_buffer_128,
-}
-
-// hash_string_256 will hash the given input and return the
-// computed hash
-hash_string_256 :: proc(data: string) -> [DIGEST_SIZE_256]byte {
-	return hash_bytes_256(transmute([]byte)(data))
-}
-
-// hash_bytes_256 will hash the given input and return the
-// computed hash
-hash_bytes_256 :: proc(data: []byte) -> [DIGEST_SIZE_256]byte {
-	hash: [DIGEST_SIZE_256]byte
-	ctx: Context
-	ctx.mdlen = DIGEST_SIZE_256
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash[:])
-	return hash
+// init_128 initializes a Context for SHAKE128.
+init_128 :: proc(ctx: ^Context) {
+	ctx.mdlen = 128 / 8
+	_init(ctx)
 }
 
-// hash_string_to_buffer_256 will hash the given input and assign the
-// computed hash to the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_string_to_buffer_256 :: proc(data: string, hash: []byte) {
-	hash_bytes_to_buffer_256(transmute([]byte)(data), hash)
+// init_256 initializes a Context for SHAKE256.
+init_256 :: proc(ctx: ^Context) {
+	ctx.mdlen = 256 / 8
+	_init(ctx)
 }
 
-// hash_bytes_to_buffer_256 will hash the given input and write the
-// computed hash into the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_bytes_to_buffer_256 :: proc(data, hash: []byte) {
-	ctx: Context
-	ctx.mdlen = DIGEST_SIZE_256
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash[:])
+@(private)
+_init :: proc(ctx: ^Context) {
+	_sha3.init(transmute(^_sha3.Context)(ctx))
 }
 
-// hash_stream_256 will read the stream in chunks and compute a
-// hash from its contents
-hash_stream_256 :: proc(s: io.Stream) -> ([DIGEST_SIZE_256]byte, bool) {
-	hash: [DIGEST_SIZE_256]byte
-	ctx: Context
-	ctx.mdlen = DIGEST_SIZE_256
-	init(&ctx)
-
-	buf := make([]byte, 512)
-	defer delete(buf)
-
-	read := 1
-	for read > 0 {
-		read, _ = io.read(s, buf)
-		if read > 0 {
-			update(&ctx, buf[:read])
-		}
-	}
-	final(&ctx, hash[:])
-	return hash, true
+// write writes more data into the SHAKE instance.  This MUST not be called
+// after any reads have been done, and attempts to do so will panic.
+write :: proc(ctx: ^Context, data: []byte) {
+	_sha3.update(transmute(^_sha3.Context)(ctx), data)
 }
 
-// hash_file_256 will read the file provided by the given handle
-// and compute a hash
-hash_file_256 :: proc(hd: os.Handle, load_at_once := false) -> ([DIGEST_SIZE_256]byte, bool) {
-	if !load_at_once {
-		return hash_stream_256(os.stream_from_handle(hd))
-	} else {
-		if buf, ok := os.read_entire_file(hd); ok {
-			return hash_bytes_256(buf[:]), ok
-		}
+// read reads output from the SHAKE instance.  There is no practical upper
+// limit to the amount of data that can be read from SHAKE.  After read has
+// been called one or more times, further calls to write will panic.
+read :: proc(ctx: ^Context, dst: []byte) {
+	ctx_ := transmute(^_sha3.Context)(ctx)
+	if !ctx.is_finalized {
+		_sha3.shake_xof(ctx_)
 	}
-	return [DIGEST_SIZE_256]byte{}, false
-}
-
-hash_256 :: proc {
-	hash_stream_256,
-	hash_file_256,
-	hash_bytes_256,
-	hash_string_256,
-	hash_bytes_to_buffer_256,
-	hash_string_to_buffer_256,
-}
-
-/*
-    Low level API
-*/
-
-Context :: _sha3.Sha3_Context
 
-init :: proc(ctx: ^Context) {
-	_sha3.init(ctx)
+	_sha3.shake_out(ctx_, dst)
 }
 
-update :: proc(ctx: ^Context, data: []byte) {
-	_sha3.update(ctx, data)
+// clone clones the Context other into ctx.
+clone :: proc(ctx, other: ^Context) {
+	_sha3.clone(transmute(^_sha3.Context)(ctx), transmute(^_sha3.Context)(other))
 }
 
-final :: proc(ctx: ^Context, hash: []byte) {
-	_sha3.shake_xof(ctx)
-	_sha3.shake_out(ctx, hash[:])
+// reset sanitizes the Context.  The Context must be re-initialized to
+// be used again.
+reset :: proc(ctx: ^Context) {
+	_sha3.reset(transmute(^_sha3.Context)(ctx))
 }
diff --git a/core/crypto/sm3/sm3.odin b/core/crypto/sm3/sm3.odin
index 7a7a0b8a6..2faf37380 100644
--- a/core/crypto/sm3/sm3.odin
+++ b/core/crypto/sm3/sm3.odin
@@ -1,3 +1,9 @@
+/*
+package sm3 implements the SM3 hash algorithm.
+
+See:
+- https://datatracker.ietf.org/doc/html/draft-sca-cfrg-sm3-02
+*/
 package sm3
 
 /*
@@ -6,102 +12,29 @@ package sm3
 
     List of contributors:
         zhibog, dotbmp:  Initial implementation.
-
-    Implementation of the SM3 hashing algorithm, as defined in <https://datatracker.ietf.org/doc/html/draft-sca-cfrg-sm3-02>
 */
 
 import "core:encoding/endian"
-import "core:io"
 import "core:math/bits"
-import "core:os"
-
-/*
-    High level API
-*/
+import "core:mem"
 
+// DIGEST_SIZE is the SM3 digest size in bytes.
 DIGEST_SIZE :: 32
 
-// hash_string will hash the given input and return the
-// computed hash
-hash_string :: proc(data: string) -> [DIGEST_SIZE]byte {
-	return hash_bytes(transmute([]byte)(data))
-}
-
-// hash_bytes will hash the given input and return the
-// computed hash
-hash_bytes :: proc(data: []byte) -> [DIGEST_SIZE]byte {
-	hash: [DIGEST_SIZE]byte
-	ctx: Context
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash[:])
-	return hash
-}
-
-// hash_string_to_buffer will hash the given input and assign the
-// computed hash to the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_string_to_buffer :: proc(data: string, hash: []byte) {
-	hash_bytes_to_buffer(transmute([]byte)(data), hash)
-}
-
-// hash_bytes_to_buffer will hash the given input and write the
-// computed hash into the second parameter.
-// It requires that the destination buffer is at least as big as the digest size
-hash_bytes_to_buffer :: proc(data, hash: []byte) {
-	ctx: Context
-	init(&ctx)
-	update(&ctx, data)
-	final(&ctx, hash)
-}
-
-// hash_stream will read the stream in chunks and compute a
-// hash from its contents
-hash_stream :: proc(s: io.Stream) -> ([DIGEST_SIZE]byte, bool) {
-	hash: [DIGEST_SIZE]byte
-	ctx: Context
-	init(&ctx)
-
-	buf := make([]byte, 512)
-	defer delete(buf)
-
-	read := 1
-	for read > 0 {
-		read, _ = io.read(s, buf)
-		if read > 0 {
-			update(&ctx, buf[:read])
-		}
-	}
-	final(&ctx, hash[:])
-	return hash, true
-}
+// BLOCK_SIZE is the SM3 block size in bytes.
+BLOCK_SIZE :: 64
 
-// hash_file will read the file provided by the given handle
-// and compute a hash
-hash_file :: proc(hd: os.Handle, load_at_once := false) -> ([DIGEST_SIZE]byte, bool) {
-	if !load_at_once {
-		return hash_stream(os.stream_from_handle(hd))
-	} else {
-		if buf, ok := os.read_entire_file(hd); ok {
-			return hash_bytes(buf[:]), ok
-		}
-	}
-	return [DIGEST_SIZE]byte{}, false
-}
+// Context is a SM3 instance.
+Context :: struct {
+	state:     [8]u32,
+	x:         [BLOCK_SIZE]byte,
+	bitlength: u64,
+	length:    u64,
 
-hash :: proc {
-	hash_stream,
-	hash_file,
-	hash_bytes,
-	hash_string,
-	hash_bytes_to_buffer,
-	hash_string_to_buffer,
+	is_initialized: bool,
 }
 
-/*
-    Low level API
-*/
-
+// init initializes a Context.
 init :: proc(ctx: ^Context) {
 	ctx.state[0] = IV[0]
 	ctx.state[1] = IV[1]
@@ -118,6 +51,7 @@ init :: proc(ctx: ^Context) {
 	ctx.is_initialized = true
 }
 
+// update adds more data to the Context.
 update :: proc(ctx: ^Context, data: []byte) {
 	assert(ctx.is_initialized)
 
@@ -143,13 +77,26 @@ update :: proc(ctx: ^Context, data: []byte) {
 	}
 }
 
-final :: proc(ctx: ^Context, hash: []byte) {
+// final finalizes the Context, writes the digest to hash, and calls
+// reset on the Context.
+//
+// Iff finalize_clone is set, final will work on a copy of the Context,
+// which is useful for for calculating rolling digests.
+final :: proc(ctx: ^Context, hash: []byte, finalize_clone: bool = false) {
 	assert(ctx.is_initialized)
 
 	if len(hash) < DIGEST_SIZE {
 		panic("crypto/sm3: invalid destination digest size")
 	}
 
+	ctx := ctx
+	if finalize_clone {
+		tmp_ctx: Context
+		clone(&tmp_ctx, ctx)
+		ctx = &tmp_ctx
+	}
+	defer(reset(ctx))
+
 	length := ctx.length
 
 	pad: [BLOCK_SIZE]byte
@@ -168,25 +115,27 @@ final :: proc(ctx: ^Context, hash: []byte) {
 	for i := 0; i < DIGEST_SIZE / 4; i += 1 {
 		endian.unchecked_put_u32be(hash[i * 4:], ctx.state[i])
 	}
+}
 
-	ctx.is_initialized = false
+// clone clones the Context other into ctx.
+clone :: proc(ctx, other: ^Context) {
+	ctx^ = other^
+}
+
+// reset sanitizes the Context.  The Context must be re-initialized to
+// be used again.
+reset :: proc(ctx: ^Context) {
+	if !ctx.is_initialized {
+		return
+	}
+
+	mem.zero_explicit(ctx, size_of(ctx^))
 }
 
 /*
     SM3 implementation
 */
 
-BLOCK_SIZE :: 64
-
-Context :: struct {
-	state:     [8]u32,
-	x:         [BLOCK_SIZE]byte,
-	bitlength: u64,
-	length:    u64,
-
-	is_initialized: bool,
-}
-
 @(private)
 IV := [8]u32 {
 	0x7380166f, 0x4914b2b9, 0x172442d7, 0xda8a0600,