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cipher: replace init args with a implementation-specific params struct

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This allows for more flexibility in the future. While at it, do note
that the RFC and draft implementations are followed. In particular, in
XChaCha20, hardcode the high word of the counter to 0.

This commit breaks ChaCha20-Poly1305. It'll be fixed in a subsequent
commit.
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This commit is contained in:
Lucas Gabriel Vuotto 2024-06-07 18:52:46 +00:00
parent b26a9c7274
commit 623dd16dc2
5 changed files with 52 additions and 111 deletions
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78
cipher_chacha20.c
View file

@ -19,57 +19,49 @@
#include "lilcrypto.h"
#include "cipher.h"
#include "cipher_chacha20.h"
#include "impl_chacha20.h"
#include "util.h"
int
chacha20_common_init_from(void *arg, const uint8_t *key, size_t keylen,
const uint8_t *iv, size_t ivlen, uint32_t counter)
{
struct chacha20_ctx *ctx = arg;
size_t i;
/*
* Implements ChaCha20 according to RFC 8439, XChaCha20 according to
* draft-irtf-cfrg-xchacha-03.
*/
if (keylen != LC_CHACHA20_KEYLEN || ivlen != LC_CHACHA20_NONCELEN)
return 0;
static int
chacha20_common_init(void *arg, const void *initparams)
{
const struct lc_chacha20_params *params = initparams;
struct chacha20_ctx *ctx = arg;
size_t i;
for (i = 0; i < CHACHA20_CHUNK_WORDS; i++)
ctx->s[i] = 0;
for (i = 0; i < CHACHA20_KEY_WORDS; i++)
ctx->k[i] = load32le(&key[i * 4]);
ctx->n[0] = counter;
ctx->k[i] = load32le(&params->key[i * 4]);
ctx->n[0] = params->counter;
for (i = 1; i < CHACHA20_NONCE_WORDS; i++)
ctx->n[i] = load32le(&iv[(i - 1) * 4]);
ctx->n[i] = load32le(&params->nonce[(i - 1) * 4]);
ctx->mlen = 0;
return 1;
}
int
chacha20_common_init(void *arg, const uint8_t *key, size_t keylen,
const uint8_t *iv, size_t ivlen)
static int
xchacha20_common_init(void *arg, const void *initparams)
{
return chacha20_common_init_from(arg, key, keylen, iv, ivlen, 0);
}
int
xchacha20_common_init_from(void *arg, const uint8_t *key, size_t keylen,
const uint8_t *iv, size_t ivlen, uint64_t counter)
{
struct chacha20_ctx *ctx = arg;
size_t i;
if (keylen != LC_XCHACHA20_KEYLEN || ivlen != LC_XCHACHA20_NONCELEN)
return 0;
const struct lc_xchacha20_params *params = initparams;
struct chacha20_ctx *ctx = arg;
size_t i;
for (i = 0; i < CHACHA20_CHUNK_WORDS; i++)
ctx->s[i] = 0;
for (i = 0; i < CHACHA20_KEY_WORDS; i++)
ctx->k[i] = load32le(&key[i * 4]);
ctx->k[i] = load32le(&params->key[i * 4]);
for (i = 0; i < CHACHA20_NONCE_WORDS; i++)
ctx->n[i] = load32le(&iv[i * 4]);
ctx->n[i] = load32le(&params->nonce[i * 4]);
ctx->mlen = 0;
hchacha20_block(ctx);
@ -82,22 +74,15 @@ xchacha20_common_init_from(void *arg, const uint8_t *key, size_t keylen,
ctx->k[5] = ctx->s[13];
ctx->k[6] = ctx->s[14];
ctx->k[7] = ctx->s[15];
ctx->n[0] = counter;
ctx->n[1] = counter >> 32;
ctx->n[2] = load32le(&iv[16]);
ctx->n[3] = load32le(&iv[20]);
ctx->n[0] = params->counter;
ctx->n[1] = 0;
ctx->n[2] = load32le(&params->nonce[16]);
ctx->n[3] = load32le(&params->nonce[20]);
return 1;
}
int
xchacha20_common_init(void *arg, const uint8_t *key, size_t keylen,
const uint8_t *iv, size_t ivlen)
{
return xchacha20_common_init_from(arg, key, keylen, iv, ivlen, 0);
}
int
static int
chacha20_common_update(void *arg, uint8_t *out, size_t *outlen,
const uint8_t *in, size_t inlen)
{
@ -159,7 +144,7 @@ chacha20_common_update(void *arg, uint8_t *out, size_t *outlen,
return 1;
}
int
static int
chacha20_common_final(void *arg, uint8_t *out, size_t *outlen)
{
struct chacha20_ctx *ctx = arg;
@ -192,10 +177,9 @@ chacha20_common_final(void *arg, uint8_t *out, size_t *outlen)
return 1;
}
int
chacha20_common(uint8_t *out, size_t *outlen, const uint8_t *key,
size_t keylen, const uint8_t *iv, size_t ivlen, const uint8_t *in,
size_t inlen)
static int
chacha20_common(uint8_t *out, size_t *outlen, const void *initparams,
const uint8_t *in, size_t inlen)
{
struct chacha20_ctx ctx;
size_t l0, l1;
@ -212,7 +196,7 @@ chacha20_common(uint8_t *out, size_t *outlen, const uint8_t *key,
return 1;
}
rc = chacha20_common_init(&ctx, key, keylen, iv, ivlen) &&
rc = chacha20_common_init(&ctx, initparams) &&
chacha20_common_update(&ctx, out, &l0, in, inlen) &&
chacha20_common_final(&ctx, out + l0, &l1);