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Refactor ChaCha into a saner interface, ep. 2.

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This commit is contained in:
Milan Špinka
2025-01-27 02:08:13 +01:00
parent 633eb083b6
commit bb8a474089
1 changed files with 29 additions and 4 deletions
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33
src/primitive/streamcipher/chacha20.zig
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@ -39,7 +39,16 @@ pub const ChaCha20Ctx = struct {
keystream_idx: u6,
};
pub fn chacha20_new(key: *const [CHACHA20_KEY_SIZE]u8, nonce: *const [CHACHA20_NONCE_SIZE]u8) ChaCha20Ctx {
pub fn chacha20_new(
key: *const [CHACHA20_KEY_SIZE]u8,
counter_size: comptime_int,
counter: *const [counter_size]u8,
nonce_size: comptime_int,
nonce: *const [nonce_size]u8,
) ChaCha20Ctx {
if (comptime counter_size + nonce_size != CHACHA20_NONCE_SIZE)
@panic("Invalid ChaCha initialization: The size of counter and nonce must add up to 16 bytes.");
var ctx = ChaCha20Ctx{
.key = undefined,
.nonce = undefined,
@ -48,8 +57,12 @@ pub fn chacha20_new(key: *const [CHACHA20_KEY_SIZE]u8, nonce: *const [CHACHA20_N
.keystream_idx = undefined,
};
const counter_words = comptime counter_size / 4;
const nonce_words = comptime nonce_size / 4;
chacha20_deserialize(CHACHA20_KEY_WORDS, key, &ctx.key);
chacha20_deserialize(CHACHA20_NONCE_WORDS, nonce, &ctx.nonce);
chacha20_deserialize(counter_words, counter, ctx.nonce[0..counter_words]);
chacha20_deserialize(nonce_words, nonce, ctx.nonce[counter_words .. counter_words + nonce_words]);
chacha20_block_function(&ctx);
ctx.keystream_idx = 0;
@ -69,7 +82,13 @@ pub fn chacha20_bernstein_new(
nonce: *const [ChaCha20_Bernstein_Parameters.NONCE_SIZE]u8,
counter: *const [ChaCha20_Bernstein_Parameters.COUNTER_SIZE]u8,
) ChaCha20Ctx {
return chacha20_new(key, counter ++ nonce);
return chacha20_new(
key,
ChaCha20_Bernstein_Parameters.COUNTER_SIZE,
counter,
ChaCha20_Bernstein_Parameters.NONCE_SIZE,
nonce,
);
}
pub fn chacha20_rfc7539_new(
@ -77,7 +96,13 @@ pub fn chacha20_rfc7539_new(
nonce: *const [ChaCha20_RFC7539_Parameters.NONCE_SIZE]u8,
counter: *const [ChaCha20_RFC7539_Parameters.COUNTER_SIZE]u8,
) ChaCha20Ctx {
return chacha20_new(key, counter ++ nonce);
return chacha20_new(
key,
ChaCha20_RFC7539_Parameters.COUNTER_SIZE,
counter,
ChaCha20_RFC7539_Parameters.NONCE_SIZE,
nonce,
);
}
pub fn chacha20_quarter_round(