tls: speed up prf_hmac_sha256()

function                                             old     new   delta
hmac_sha_precomputed                                   -      58     +58
prf_hmac_sha256                                      181     222     +41
hmac_sha256                                           68       -     -68
------------------------------------------------------------------------------
(add/remove: 1/1 grow/shrink: 1/0 up/down: 99/-68)             Total: 31 bytes

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

1 files changed, 39 insertions, 40 deletions

diff --git a/networking/tls.c b/networking/tls.c
index 002983273..6c87e12ff 100644
--- a/networking/tls.c
+++ b/networking/tls.c
@@ -420,29 +420,6 @@ typedef struct hmac_precomputed {
         md5sha_ctx_t hashed_key_xor_opad;
 } hmac_precomputed_t;
 
-static unsigned hmac_sha_precomputed_v(
-                hmac_precomputed_t *pre,
-                uint8_t *out,
-                va_list va)
-{
-        uint8_t *text;
-        unsigned len;
-
-        /* pre->hashed_key_xor_ipad contains unclosed "H((key XOR ipad) +" state */
-        /* pre->hashed_key_xor_opad contains unclosed "H((key XOR opad) +" state */
-
-        /* calculate out = H((key XOR ipad) + text) */
-        while ((text = va_arg(va, uint8_t*)) != NULL) {
-                unsigned text_size = va_arg(va, unsigned);
-                md5sha_hash(&pre->hashed_key_xor_ipad, text, text_size);
-        }
-        len = sha_end(&pre->hashed_key_xor_ipad, out);
-
-        /* out = H((key XOR opad) + out) */
-        md5sha_hash(&pre->hashed_key_xor_opad, out, len);
-        return sha_end(&pre->hashed_key_xor_opad, out);
-}
-
 typedef void md5sha_begin_func(md5sha_ctx_t *ctx) FAST_FUNC;
 static void hmac_begin(hmac_precomputed_t *pre, uint8_t *key, unsigned key_size, md5sha_begin_func *begin)
 {
@@ -485,26 +462,43 @@ static void hmac_begin(hmac_precomputed_t *pre, uint8_t *key, unsigned key_size,
         md5sha_hash(&pre->hashed_key_xor_opad, key_xor_opad, SHA_INSIZE);
 }
 
-static unsigned hmac(tls_state_t *tls, uint8_t *out, uint8_t *key, unsigned key_size, ...)
+static unsigned hmac_sha_precomputed_v(
+                hmac_precomputed_t *pre,
+                uint8_t *out,
+                va_list va)
+{
+        uint8_t *text;
+        unsigned len;
+
+        /* pre->hashed_key_xor_ipad contains unclosed "H((key XOR ipad) +" state */
+        /* pre->hashed_key_xor_opad contains unclosed "H((key XOR opad) +" state */
+
+        /* calculate out = H((key XOR ipad) + text) */
+        while ((text = va_arg(va, uint8_t*)) != NULL) {
+                unsigned text_size = va_arg(va, unsigned);
+                md5sha_hash(&pre->hashed_key_xor_ipad, text, text_size);
+        }
+        len = sha_end(&pre->hashed_key_xor_ipad, out);
+
+        /* out = H((key XOR opad) + out) */
+        md5sha_hash(&pre->hashed_key_xor_opad, out, len);
+        return sha_end(&pre->hashed_key_xor_opad, out);
+}
+
+static unsigned hmac_sha_precomputed(hmac_precomputed_t *pre_init, uint8_t *out, ...)
 {
         hmac_precomputed_t pre;
         va_list va;
         unsigned len;
 
-        va_start(va, key_size);
-
-        hmac_begin(&pre, key, key_size,
-                        (tls->MAC_size == SHA256_OUTSIZE)
-                                ? sha256_begin
-                                : sha1_begin
-        );
+        va_start(va, out);
+        pre = *pre_init; /* struct copy */
         len = hmac_sha_precomputed_v(&pre, out, va);
-
         va_end(va);
         return len;
 }
 
-static unsigned hmac_sha256(/*tls_state_t *tls,*/ uint8_t *out, uint8_t *key, unsigned key_size, ...)
+static unsigned hmac(tls_state_t *tls, uint8_t *out, uint8_t *key, unsigned key_size, ...)
 {
         hmac_precomputed_t pre;
         va_list va;
@@ -512,7 +506,11 @@ static unsigned hmac_sha256(/*tls_state_t *tls,*/ uint8_t *out, uint8_t *key, un
 
         va_start(va, key_size);
 
-        hmac_begin(&pre, key, key_size, sha256_begin);
+        hmac_begin(&pre, key, key_size,
+                        (tls->MAC_size == SHA256_OUTSIZE)
+                                ? sha256_begin
+                                : sha1_begin
+        );
         len = hmac_sha_precomputed_v(&pre, out, va);
 
         va_end(va);
@@ -563,6 +561,7 @@ static void prf_hmac_sha256(/*tls_state_t *tls,*/
                 const char *label,
                 uint8_t *seed, unsigned seed_size)
 {
+        hmac_precomputed_t pre;
         uint8_t a[TLS_MAX_MAC_SIZE];
         uint8_t *out_p = outbuf;
         unsigned label_size = strlen(label);
@@ -570,28 +569,28 @@ static void prf_hmac_sha256(/*tls_state_t *tls,*/
 
         /* In P_hash() calculation, "seed" is "label + seed": */
 #define SEED   label, label_size, seed, seed_size
-#define SECRET secret, secret_size
 #define A      a, MAC_size
 
+        hmac_begin(&pre, secret, secret_size, sha256_begin);
+
         /* A(1) = HMAC_hash(secret, seed) */
-        hmac_sha256(/*tls,*/ a, SECRET, SEED, NULL);
-//TODO: convert hmac to precomputed
+        hmac_sha_precomputed(&pre, a, SEED, NULL);
 
         for (;;) {
                 /* HMAC_hash(secret, A(1) + seed) */
                 if (outbuf_size <= MAC_size) {
                         /* Last, possibly incomplete, block */
                         /* (use a[] as temp buffer) */
-                        hmac_sha256(/*tls,*/ a, SECRET, A, SEED, NULL);
+                        hmac_sha_precomputed(&pre, a, A, SEED, NULL);
                         memcpy(out_p, a, outbuf_size);
                         return;
                 }
                 /* Not last block. Store directly to result buffer */
-                hmac_sha256(/*tls,*/ out_p, SECRET, A, SEED, NULL);
+                hmac_sha_precomputed(&pre, out_p, A, SEED, NULL);
                 out_p += MAC_size;
                 outbuf_size -= MAC_size;
                 /* A(2) = HMAC_hash(secret, A(1)) */
-                hmac_sha256(/*tls,*/ a, SECRET, A, NULL);
+                hmac_sha_precomputed(&pre, a, A, NULL);
         }
 #undef A
 #undef SECRET