libbb/yescrypt: shrink PBKDF2

function                                             old     new   delta
static.PBKDF2_SHA256                                 189     176     -13

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 14 insertions, 14 deletions

diff --git a/libbb/yescrypt/alg-sha256.c b/libbb/yescrypt/alg-sha256.c
index 28d8c5296..f56b905ad 100644
--- a/libbb/yescrypt/alg-sha256.c
+++ b/libbb/yescrypt/alg-sha256.c
@@ -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;
         }
 }