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/*
`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
/*
Copyright 2021 zhibog
Made available under the BSD-3 license.
List of contributors:
zhibog, dotbmp: Initial implementation.
*/
import "core:encoding/endian"
import "core:math/bits"
import "core:mem"
// DIGEST_SIZE is the SHA1 digest size in bytes.
DIGEST_SIZE :: 20
// BLOCK_SIZE is the SHA1 block size in bytes.
BLOCK_SIZE :: 64
// Context is a SHA1 instance.
Context :: struct {
data: [BLOCK_SIZE]byte,
state: [5]u32,
k: [4]u32,
bitlen: u64,
datalen: u32,
is_initialized: bool,
}
// init initializes a Context.
init :: proc(ctx: ^Context) {
ctx.state[0] = 0x67452301
ctx.state[1] = 0xefcdab89
ctx.state[2] = 0x98badcfe
ctx.state[3] = 0x10325476
ctx.state[4] = 0xc3d2e1f0
ctx.k[0] = 0x5a827999
ctx.k[1] = 0x6ed9eba1
ctx.k[2] = 0x8f1bbcdc
ctx.k[3] = 0xca62c1d6
ctx.datalen = 0
ctx.bitlen = 0
ctx.is_initialized = true
}
// update adds more data to the Context.
update :: proc(ctx: ^Context, data: []byte) {
ensure(ctx.is_initialized)
for i := 0; i < len(data); i += 1 {
ctx.data[ctx.datalen] = data[i]
ctx.datalen += 1
if (ctx.datalen == BLOCK_SIZE) {
transform(ctx, ctx.data[:])
ctx.bitlen += 512
ctx.datalen = 0
}
}
}
// 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) {
ensure(ctx.is_initialized)
ensure(len(hash) >= DIGEST_SIZE, "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 {
ctx.data[i] = 0x80
i += 1
for i < 56 {
ctx.data[i] = 0x00
i += 1
}
} else {
ctx.data[i] = 0x80
i += 1
for i < BLOCK_SIZE {
ctx.data[i] = 0x00
i += 1
}
transform(ctx, ctx.data[:])
mem.set(&ctx.data, 0, 56)
}
ctx.bitlen += u64(ctx.datalen * 8)
endian.unchecked_put_u64be(ctx.data[56:], ctx.bitlen)
transform(ctx, ctx.data[:])
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
}
mem.zero_explicit(ctx, size_of(ctx^))
}
/*
SHA1 implementation
*/
@(private)
transform :: proc "contextless" (ctx: ^Context, data: []byte) {
a, b, c, d, e, i, t: u32
m: [80]u32
for i = 0; i < 16; i += 1 {
m[i] = endian.unchecked_get_u32be(data[i * 4:])
}
for i < 80 {
m[i] = (m[i - 3] ~ m[i - 8] ~ m[i - 14] ~ m[i - 16])
m[i] = (m[i] << 1) | (m[i] >> 31)
i += 1
}
a = ctx.state[0]
b = ctx.state[1]
c = ctx.state[2]
d = ctx.state[3]
e = ctx.state[4]
for i = 0; i < 20; i += 1 {
t = bits.rotate_left32(a, 5) + ((b & c) ~ (~b & d)) + e + ctx.k[0] + m[i]
e = d
d = c
c = bits.rotate_left32(b, 30)
b = a
a = t
}
for i < 40 {
t = bits.rotate_left32(a, 5) + (b ~ c ~ d) + e + ctx.k[1] + m[i]
e = d
d = c
c = bits.rotate_left32(b, 30)
b = a
a = t
i += 1
}
for i < 60 {
t = bits.rotate_left32(a, 5) + ((b & c) ~ (b & d) ~ (c & d)) + e + ctx.k[2] + m[i]
e = d
d = c
c = bits.rotate_left32(b, 30)
b = a
a = t
i += 1
}
for i < 80 {
t = bits.rotate_left32(a, 5) + (b ~ c ~ d) + e + ctx.k[3] + m[i]
e = d
d = c
c = bits.rotate_left32(b, 30)
b = a
a = t
i += 1
}
ctx.state[0] += a
ctx.state[1] += b
ctx.state[2] += c
ctx.state[3] += d
ctx.state[4] += e
}
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