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core/crypto: Misc cleanups and documentation improvements

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This commit is contained in:
Yawning Angel
2024-03-04 17:50:45 +09:00
parent b818ebc02f
commit fa8dd5a13b
5 changed files with 108 additions and 39 deletions
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core/crypto/poly1305/poly1305.odin
+38 -17
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@@ -1,3 +1,9 @@
/*
package poly1305 implements the Poly1305 one-time MAC algorithm.
See:
- https://datatracker.ietf.org/doc/html/rfc8439
*/
package poly1305
import "core:crypto"
@@ -5,13 +11,20 @@ import field "core:crypto/_fiat/field_poly1305"
import "core:encoding/endian"
import "core:mem"
// KEY_SIZE is the Poly1305 key size in bytes.
KEY_SIZE :: 32
// TAG_SIZE is the Poly1305 tag size in bytes.
TAG_SIZE :: 16
@(private)
_BLOCK_SIZE :: 16
sum :: proc (dst, msg, key: []byte) {
// sum will compute the Poly1305 MAC with the key over msg, and write
// the computed tag to dst. It requires that the dst buffer is the tag
// size.
//
// The key SHOULD be unique and MUST be unpredictable for each invocation.
sum :: proc(dst, msg, key: []byte) {
ctx: Context = ---
init(&ctx, key)
@@ -19,9 +32,12 @@ sum :: proc (dst, msg, key: []byte) {
final(&ctx, dst)
}
verify :: proc (tag, msg, key: []byte) -> bool {
// verify will verify the Poly1305 tag computed with the key over msg and
// return true iff the tag is valid. It requires that the tag is correctly
// sized.
verify :: proc(tag, msg, key: []byte) -> bool {
ctx: Context = ---
derived_tag: [16]byte = ---
derived_tag: [TAG_SIZE]byte = ---
init(&ctx, key)
update(&ctx, msg)
@@ -30,18 +46,19 @@ verify :: proc (tag, msg, key: []byte) -> bool {
return crypto.compare_constant_time(derived_tag[:], tag) == 1
}
// Context is a Poly1305 instance.
Context :: struct {
_r: field.Tight_Field_Element,
_a: field.Tight_Field_Element,
_s: field.Tight_Field_Element,
_buffer: [_BLOCK_SIZE]byte,
_leftover: int,
_r: field.Tight_Field_Element,
_a: field.Tight_Field_Element,
_s: field.Tight_Field_Element,
_buffer: [_BLOCK_SIZE]byte,
_leftover: int,
_is_initialized: bool,
}
init :: proc (ctx: ^Context, key: []byte) {
// init initializes a Context with the specified key. The key SHOULD be
// unique and MUST be unpredictable for each invocation.
init :: proc(ctx: ^Context, key: []byte) {
if len(key) != KEY_SIZE {
panic("crypto/poly1305: invalid key size")
}
@@ -64,7 +81,8 @@ init :: proc (ctx: ^Context, key: []byte) {
ctx._is_initialized = true
}
update :: proc (ctx: ^Context, data: []byte) {
// update adds more data to the Context.
update :: proc(ctx: ^Context, data: []byte) {
assert(ctx._is_initialized)
msg := data
@@ -101,8 +119,11 @@ update :: proc (ctx: ^Context, data: []byte) {
}
}
final :: proc (ctx: ^Context, dst: []byte) {
// 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) != TAG_SIZE {
panic("poly1305: invalid destination tag size")
@@ -125,11 +146,11 @@ final :: proc (ctx: ^Context, dst: []byte) {
tmp: [32]byte = ---
field.fe_to_bytes(&tmp, &ctx._a)
copy_slice(dst, tmp[0:16])
reset(ctx)
}
reset :: proc (ctx: ^Context) {
// reset sanitizes the Context. The Context must be re-initialized to
// be used again.
reset :: proc(ctx: ^Context) {
mem.zero_explicit(&ctx._r, size_of(ctx._r))
mem.zero_explicit(&ctx._a, size_of(ctx._a))
mem.zero_explicit(&ctx._s, size_of(ctx._s))
@@ -139,7 +160,7 @@ reset :: proc (ctx: ^Context) {
}
@(private)
_blocks :: proc (ctx: ^Context, msg: []byte, final := false) {
_blocks :: proc(ctx: ^Context, msg: []byte, final := false) {
n: field.Tight_Field_Element = ---
final_byte := byte(!final)