tls: in AES-CBC code, do not set key for every record - do it once

function                                             old     new   delta
aes_setkey                                            16     212    +196
tls_handshake                                       1941    1977     +36
aes_encrypt_1                                        382     396     +14
xwrite_encrypted                                     605     604      -1
tls_xread_record                                     659     656      -3
aes_encrypt_one_block                                 65      59      -6
aes_cbc_encrypt                                      172     121     -51
aesgcm_setkey                                         58       -     -58
aes_cbc_decrypt                                      958     881     -77
KeyExpansion                                         188       -    -188
------------------------------------------------------------------------------
(add/remove: 0/2 grow/shrink: 3/5 up/down: 246/-384)         Total: -138 bytes

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

1 files changed, 17 insertions, 15 deletions

diff --git a/networking/tls_aes.c b/networking/tls_aes.c
index 4d2b68975..cf6b5fe3d 100644
--- a/networking/tls_aes.c
+++ b/networking/tls_aes.c
@@ -326,8 +326,11 @@ static void InvMixColumns(unsigned astate[16])
         }
 }
 
-static void aes_encrypt_1(unsigned astate[16], unsigned rounds, const uint32_t *RoundKey)
+static void aes_encrypt_1(struct tls_aes *aes, unsigned astate[16])
 {
+        unsigned rounds = aes->rounds;
+        const uint32_t *RoundKey = aes->key;
+
         for (;;) {
                 AddRoundKey(astate, RoundKey);
                 RoundKey += 4;
@@ -355,22 +358,19 @@ void FAST_FUNC aes_encrypt_one_block(struct tls_aes *aes, const void *data, void
 
         for (i = 0; i < 16; i++)
                 astate[i] = pt[i];
-        aes_encrypt_1(astate, aes->rounds, aes->key);
+        aes_encrypt_1(aes, astate);
         for (i = 0; i < 16; i++)
                 ct[i] = astate[i];
 }
 
-void FAST_FUNC aes_cbc_encrypt(const void *key, int klen, void *iv, const void *data, size_t len, void *dst)
+void FAST_FUNC aes_cbc_encrypt(struct tls_aes *aes, void *iv, const void *data, size_t len, void *dst)
 {
-        uint32_t RoundKey[60];
         uint8_t iv2[16];
-        unsigned rounds;
 
         const uint8_t *pt = data;
         uint8_t *ct = dst;
 
         memcpy(iv2, iv, 16);
-        rounds = KeyExpansion(RoundKey, key, klen);
         while (len > 0) {
                 {
                         /* almost aes_encrypt_one_block(rounds, RoundKey, pt, ct);
@@ -381,7 +381,7 @@ void FAST_FUNC aes_cbc_encrypt(const void *key, int klen, void *iv, const void *
                         unsigned astate[16];
                         for (i = 0; i < 16; i++)
                                 astate[i] = pt[i] ^ iv2[i];
-                        aes_encrypt_1(astate, rounds, RoundKey);
+                        aes_encrypt_1(aes, astate);
                         for (i = 0; i < 16; i++)
                                 iv2[i] = ct[i] = astate[i];
                 }
@@ -391,8 +391,11 @@ void FAST_FUNC aes_cbc_encrypt(const void *key, int klen, void *iv, const void *
         }
 }
 
-static void aes_decrypt_1(unsigned astate[16], unsigned rounds, const uint32_t *RoundKey)
+static void aes_decrypt_1(struct tls_aes *aes, unsigned astate[16])
 {
+        unsigned rounds = aes->rounds;
+        const uint32_t *RoundKey = aes->key;
+
         RoundKey += rounds * 4;
         AddRoundKey(astate, RoundKey);
         for (;;) {
@@ -407,8 +410,10 @@ static void aes_decrypt_1(unsigned astate[16], unsigned rounds, const uint32_t *
 }
 
 #if 0 //UNUSED
-static void aes_decrypt_one_block(unsigned rounds, const uint32_t *RoundKey, const void *data, void *dst)
+static void aes_decrypt_one_block(struct tls_aes *aes, const void *data, void *dst)
 {
+        unsigned rounds = aes->rounds;
+        const uint32_t *RoundKey = aes->key;
         unsigned astate[16];
         unsigned i;
 
@@ -417,25 +422,22 @@ static void aes_decrypt_one_block(unsigned rounds, const uint32_t *RoundKey, con
 
         for (i = 0; i < 16; i++)
                 astate[i] = ct[i];
-        aes_decrypt_1(astate, rounds, RoundKey);
+        aes_decrypt_1(aes, astate);
         for (i = 0; i < 16; i++)
                 pt[i] = astate[i];
 }
 #endif
 
-void FAST_FUNC aes_cbc_decrypt(const void *key, int klen, void *iv, const void *data, size_t len, void *dst)
+void FAST_FUNC aes_cbc_decrypt(struct tls_aes *aes, void *iv, const void *data, size_t len, void *dst)
 {
-        uint32_t RoundKey[60];
         uint8_t iv2[16];
         uint8_t iv3[16];
-        unsigned rounds;
         uint8_t *ivbuf;
         uint8_t *ivnext;
 
         const uint8_t *ct = data;
         uint8_t *pt = dst;
 
-        rounds = KeyExpansion(RoundKey, key, klen);
         ivbuf = memcpy(iv2, iv, 16);
         while (len) {
                 ivnext = (ivbuf==iv2) ? iv3 : iv2;
@@ -447,7 +449,7 @@ void FAST_FUNC aes_cbc_decrypt(const void *key, int klen, void *iv, const void *
                         unsigned astate[16];
                         for (i = 0; i < 16; i++)
                                 ivnext[i] = astate[i] = ct[i];
-                        aes_decrypt_1(astate, rounds, RoundKey);
+                        aes_decrypt_1(aes, astate);
                         for (i = 0; i < 16; i++)
                                 pt[i] = astate[i] ^ ivbuf[i];
                 }