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libbb/yescrypt: shrink PBKDF2

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function                                             old     new   delta
static.PBKDF2_SHA256                                 189     176     -13

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2025-07-06 18:35:37 +02:00
parent b8f7600166
commit f5af8aefea
1 changed files with 14 additions and 14 deletions
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28
libbb/yescrypt/alg-sha256.c
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@ -77,7 +77,7 @@ HMAC_SHA256_Update(HMAC_SHA256_CTX *ctx, const void *in, size_t len)
* buffer ${digest}.
*/
static void
HMAC_SHA256_Final(HMAC_SHA256_CTX *ctx, uint8_t digest[32])
HMAC_SHA256_Final(HMAC_SHA256_CTX *ctx, void *digest)
{
/* Finish the inner SHA256 operation. */
sha256_end(&ctx->ictx, digest); /* using digest[] as scratch space */
@ -93,8 +93,7 @@ HMAC_SHA256_Final(HMAC_SHA256_CTX *ctx, uint8_t digest[32])
* length ${Klen}, and write the result to ${digest}.
*/
static void
HMAC_SHA256_Buf(const void *K, size_t Klen, const void *in, size_t len,
uint8_t digest[32])
HMAC_SHA256_Buf(const void *K, size_t Klen, const void *in, size_t len, void *digest)
{
HMAC_SHA256_CTX ctx;
HMAC_SHA256_Init(&ctx, K, Klen);
@ -114,11 +113,6 @@ PBKDF2_SHA256(const uint8_t *passwd, size_t passwdlen,
{
HMAC_SHA256_CTX Phctx, PShctx, hctx;
size_t i;
uint8_t U[32];
uint8_t T[32];
uint64_t j;
int k;
size_t clen;
/* Compute HMAC state after processing P. */
HMAC_SHA256_Init(&Phctx, passwd, passwdlen);
@ -128,14 +122,19 @@ PBKDF2_SHA256(const uint8_t *passwd, size_t passwdlen,
HMAC_SHA256_Update(&PShctx, salt, saltlen);
/* Iterate through the blocks. */
for (i = 0; i * 32 < dkLen; i++) {
for (i = 0; dkLen != 0; i++) {
uint64_t U[32 / 8];
uint64_t T[32 / 8];
uint64_t j;
uint32_t ivec;
size_t clen;
int k;
/* Generate INT(i + 1). */
ivec = SWAP_BE32((uint32_t)(i + 1));
/* Compute U_1 = PRF(P, S || INT(i)). */
memcpy(&hctx, &PShctx, sizeof(HMAC_SHA256_CTX));
hctx = PShctx;
HMAC_SHA256_Update(&hctx, &ivec, 4);
HMAC_SHA256_Final(&hctx, T);
@ -144,19 +143,20 @@ PBKDF2_SHA256(const uint8_t *passwd, size_t passwdlen,
memcpy(U, T, 32);
for (j = 2; j <= c; j++) {
/* Compute U_j. */
memcpy(&hctx, &Phctx, sizeof(HMAC_SHA256_CTX));
hctx = Phctx;
HMAC_SHA256_Update(&hctx, U, 32);
HMAC_SHA256_Final(&hctx, U);
/* ... xor U_j ... */
for (k = 0; k < 32; k++)
for (k = 0; k < 32 / 8; k++)
T[k] ^= U[k];
}
}
/* Copy as many bytes as necessary into buf. */
clen = dkLen - i * 32;
clen = dkLen;
if (clen > 32)
clen = 32;
memcpy(&buf[i * 32], T, clen);
buf = mempcpy(buf, T, clen);
dkLen -= clen;
}
}