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Merge pull request #3381 from Yawning/fix/chacha20poly1305

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core/crypto/poly1305: The final addition is NOT mod p
This commit is contained in:
Jeroen van Rijn
2024-04-05 16:57:31 +02:00
committed by GitHub
parent 1422e5bc26 a45721e9ad
commit 280adc8a85
1 changed files with 17 additions and 9 deletions
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26
core/crypto/poly1305/poly1305.odin
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@@ -9,6 +9,7 @@ package poly1305
import "core:crypto"
import field "core:crypto/_fiat/field_poly1305"
import "core:encoding/endian"
import "core:math/bits"
import "core:mem"
// KEY_SIZE is the Poly1305 key size in bytes.
@@ -50,7 +51,7 @@ verify :: proc(tag, msg, key: []byte) -> bool {
Context :: struct {
_r: field.Tight_Field_Element,
_a: field.Tight_Field_Element,
_s: field.Tight_Field_Element,
_s: [2]u64,
_buffer: [_BLOCK_SIZE]byte,
_leftover: int,
_is_initialized: bool,
@@ -66,11 +67,12 @@ init :: proc(ctx: ^Context, key: []byte) {
// r = le_bytes_to_num(key[0..15])
// r = clamp(r) (r &= 0xffffffc0ffffffc0ffffffc0fffffff)
tmp_lo := endian.unchecked_get_u64le(key[0:]) & 0x0ffffffc0fffffff
tmp_hi := endian.unchecked_get_u64le(key[8:]) & 0xffffffc0ffffffc
tmp_hi := endian.unchecked_get_u64le(key[8:]) & 0x0ffffffc0ffffffc
field.fe_from_u64s(&ctx._r, tmp_lo, tmp_hi)
// s = le_bytes_to_num(key[16..31])
field.fe_from_bytes(&ctx._s, key[16:32], 0)
ctx._s[0] = endian.unchecked_get_u64le(key[16:])
ctx._s[1] = endian.unchecked_get_u64le(key[24:])
// a = 0
field.fe_zero(&ctx._a)
@@ -138,14 +140,20 @@ final :: proc(ctx: ^Context, dst: []byte) {
_blocks(ctx, ctx._buffer[:], true)
}
// a += s
field.fe_add(field.fe_relax_cast(&ctx._a), &ctx._a, &ctx._s) // _a unreduced
field.fe_carry(&ctx._a, field.fe_relax_cast(&ctx._a)) // _a reduced
// return num_to_16_le_bytes(a)
// a += s (NOT mod p)
tmp: [32]byte = ---
field.fe_to_bytes(&tmp, &ctx._a)
copy_slice(dst, tmp[0:16])
c: u64
lo := endian.unchecked_get_u64le(tmp[0:])
hi := endian.unchecked_get_u64le(tmp[8:])
lo, c = bits.add_u64(lo, ctx._s[0], 0)
hi, _ = bits.add_u64(hi, ctx._s[1], c)
// return num_to_16_le_bytes(a)
endian.unchecked_put_u64le(dst[0:], lo)
endian.unchecked_put_u64le(dst[8:], hi)
}
// reset sanitizes the Context. The Context must be re-initialized to