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];
 		}