core:crypto/hash: Add a generic higher level hash interface

There is a lot of code duplicated in convenience methods in each hash
implementation, and having a generic hash type makes implementing
higher-level constructs such as HMAC significantly easier down the road.

1 files changed, 8 insertions, 70 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