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authorMatthias Schiffer <mschiffer@universe-factory.net>2013-11-17 11:43:06 +0100
committerMatthias Schiffer <mschiffer@universe-factory.net>2013-11-17 11:43:06 +0100
commitb4c9ab9a814edfb0d735a8c2e1f0c173847c0810 (patch)
treec4a715a5e9bcbb357f00013c2ff42157899471b1 /src/crypto/mac/ghash/builtin
parent1b06460aa967e3afcfa6fc8d664874134ab6c739 (diff)
downloadfastd-b4c9ab9a814edfb0d735a8c2e1f0c173847c0810.tar
fastd-b4c9ab9a814edfb0d735a8c2e1f0c173847c0810.zip
Revert bytewise ghash implementation
The performance gain is negligible, and OpenSSL avoids a bytewise implementation to mitigate timing attacks. This reverts commits d4916544299c28c4fb16da6d3306eea0a6d5d79f and 1b06460aa967e3afcfa6fc8d664874134ab6c739.
Diffstat (limited to 'src/crypto/mac/ghash/builtin')
-rw-r--r--src/crypto/mac/ghash/builtin/ghash_builtin.c46
1 files changed, 20 insertions, 26 deletions
diff --git a/src/crypto/mac/ghash/builtin/ghash_builtin.c b/src/crypto/mac/ghash/builtin/ghash_builtin.c
index 947dc34..34e118a 100644
--- a/src/crypto/mac/ghash/builtin/ghash_builtin.c
+++ b/src/crypto/mac/ghash/builtin/ghash_builtin.c
@@ -28,7 +28,7 @@
struct fastd_mac_state {
- fastd_block128_t H[16][256];
+ fastd_block128_t H[32][16];
};
@@ -40,30 +40,22 @@ static inline uint8_t shr(fastd_block128_t *out, const fastd_block128_t *in, int
uint8_t c = 0;
for (i = 0; i < sizeof(fastd_block128_t); i++) {
+ uint8_t c2 = in->b[i] << (8-n);
out->b[i] = (in->b[i] >> n) | c;
- c = in->b[i] << (8-n);
+ c = c2;
}
return (c >> (8-n));
}
-static inline uint8_t shr8(fastd_block128_t *out, const fastd_block128_t *in) {
- size_t i;
-
- out->b[0] = 0;
-
- for (i = 1; i < sizeof(fastd_block128_t); i++)
- out->b[i] = in->b[i-1];
-
- return in->b[sizeof(fastd_block128_t)-1];
-}
-
static inline void mulH_a(fastd_block128_t *x, const fastd_mac_state_t *cstate) {
fastd_block128_t out = {};
int i;
- for (i = 0; i < 16; i++)
- xor_a(&out, &cstate->H[i][x->b[i]]);
+ for (i = 0; i < 16; i++) {
+ xor_a(&out, &cstate->H[2*i][x->b[i]>>4]);
+ xor_a(&out, &cstate->H[2*i+1][x->b[i]&0xf]);
+ }
*x = out;
}
@@ -78,16 +70,16 @@ static size_t ghash_key_length(fastd_context_t *ctx UNUSED, const fastd_mac_cont
}
static fastd_mac_state_t* ghash_init_state(fastd_context_t *ctx UNUSED, const fastd_mac_context_t *mctx UNUSED, const uint8_t *key) {
- fastd_mac_state_t *state = calloc(1, sizeof(fastd_mac_state_t));
+ fastd_mac_state_t *state = malloc(sizeof(fastd_mac_state_t));
- fastd_block128_t Hbase[8];
- fastd_block128_t Rbase[8];
+ fastd_block128_t Hbase[4];
+ fastd_block128_t Rbase[4];
memcpy(&Hbase[0], key, sizeof(fastd_block128_t));
Rbase[0] = r;
int i;
- for (i = 1; i < 8; i++) {
+ for (i = 1; i < 4; i++) {
uint8_t carry = shr(&Hbase[i], &Hbase[i-1], 1);
if (carry)
xor_a(&Hbase[i], &r);
@@ -95,23 +87,25 @@ static fastd_mac_state_t* ghash_init_state(fastd_context_t *ctx UNUSED, const fa
shr(&Rbase[i], &Rbase[i-1], 1);
}
- fastd_block128_t R[256] = {};
+ fastd_block128_t R[16];
+ memset(state->H, 0, sizeof(state->H));
+ memset(R, 0, sizeof(R));
- for (i = 0; i < 256; i++) {
+ for (i = 0; i < 16; i++) {
int j;
- for (j = 0; j < 8; j++) {
- if (i & (0x80 >> j)) {
+ for (j = 0; j < 4; j++) {
+ if (i & (8 >> j)) {
xor_a(&state->H[0][i], &Hbase[j]);
xor_a(&R[i], &Rbase[j]);
}
}
}
- for (i = 1; i < 16; i++) {
+ for (i = 1; i < 32; i++) {
int j;
- for (j = 0; j < 256; j++) {
- uint8_t carry = shr8(&state->H[i][j], &state->H[i-1][j]);
+ for (j = 0; j < 16; j++) {
+ uint8_t carry = shr(&state->H[i][j], &state->H[i-1][j], 4);
xor_a(&state->H[i][j], &R[carry]);
}
}