sha3: cosmetic tweaks to various names, comments. No logic changes.
authorDenys Vlasenko <vda.linux@googlemail.com>
Tue, 15 Jan 2013 18:52:30 +0000 (19:52 +0100)
committerDenys Vlasenko <vda.linux@googlemail.com>
Tue, 15 Jan 2013 18:52:30 +0000 (19:52 +0100)
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
libbb/hash_md5_sha.c

index 4cd2244..18e4260 100644 (file)
@@ -926,66 +926,67 @@ void FAST_FUNC sha512_end(sha512_ctx_t *ctx, void *resbuf)
 # define SHA3_SMALL CONFIG_SHA3_SMALL
 #endif
 
-#define ARCH_IS_64BIT (sizeof(long) >= sizeof(uint64_t))
-
 enum {
-       cKeccakR_SizeInBytes = 576 / 8,
-       cKeccakNumberOfRounds = 24,
+       KECCAK_IBLK_BYTES = 576 / 8,
+       KECCAK_NROUNDS = 24,
 };
 
 /* Elements should be 64-bit, but top half is always zero or 0x80000000.
- * It is encoded as a separate word below.
- * Same is true for 31th bits.
+ * We encode 63rd bits in a separate word below.
+ * Same is true for 31th bits, which lets us use 16-bit table instead of 64-bit.
+ * The speed penalty is lost in the noise.
  */
-static const uint16_t KeccakF_RoundConstants[cKeccakNumberOfRounds] = {
-       0x0001UL,
-       0x8082UL,
-       0x808aUL,
-       0x8000UL,
-       0x808bUL,
-       0x0001UL,
-       0x8081UL,
-       0x8009UL,
-       0x008aUL,
-       0x0088UL,
-       0x8009UL,
-       0x000aUL,
-       0x808bUL,
-       0x008bUL,
-       0x8089UL,
-       0x8003UL,
-       0x8002UL,
-       0x0080UL,
-       0x800aUL,
-       0x000aUL,
-       0x8081UL,
-       0x8080UL,
-       0x0001UL,
-       0x8008UL
+static const uint16_t KECCAK_IOTA_CONST[KECCAK_NROUNDS] = {
+       0x0001U,
+       0x8082U,
+       0x808aU,
+       0x8000U,
+       0x808bU,
+       0x0001U,
+       0x8081U,
+       0x8009U,
+       0x008aU,
+       0x0088U,
+       0x8009U,
+       0x000aU,
+       0x808bU,
+       0x008bU,
+       0x8089U,
+       0x8003U,
+       0x8002U,
+       0x0080U,
+       0x800aU,
+       0x000aU,
+       0x8081U,
+       0x8080U,
+       0x0001U,
+       0x8008U,
 };
-/* 0th first - 0011 0011 0000 0111 1101 1101: */
-#define KeccakF_RoundConstantBit63 ((uint32_t)(0x3307dd00))
-/* 0th first - 0001 0110 0011 1000 0001 1011: */
-#define KeccakF_RoundConstantBit31 ((uint32_t)(0x16381b00))
+/* bit from CONST[0] is msb: 0011 0011 0000 0111 1101 1101 */
+#define KECCAK_IOTA_CONST_bit63 ((uint32_t)(0x3307dd00))
+/* bit from CONST[0] is msb: 0001 0110 0011 1000 0001 1011 */
+#define KECCAK_IOTA_CONST_bit31 ((uint32_t)(0x16381b00))
 
-static const uint8_t KeccakF_RotationConstants[25] = {
+static const uint8_t KECCAK_ROT_CONST[25] = {
        1, 3, 6, 10, 15, 21, 28, 36, 45, 55, 2, 14, 27, 41, 56, 8, 25, 43, 62,
        18, 39, 61, 20, 44
 };
 
-static const uint8_t KeccakF_PiLane[25] = {
+static const uint8_t KECCAK_PI_LANE[25] = {
        10, 7, 11, 17, 18, 3, 5, 16, 8, 21, 24, 4, 15, 23, 19, 13, 12, 2, 20,
        14, 22, 9, 6, 1
 };
 
-static const uint8_t KeccakF_Mod5[10] = {
+static const uint8_t MOD5[10] = {
        0, 1, 2, 3, 4, 0, 1, 2, 3, 4
 };
 
+#define ARCH_IS_64BIT (sizeof(long) >= sizeof(uint64_t))
+
 static void KeccakF(uint64_t *state)
 {
-       uint8_t x, y;
-       int round;
+       unsigned x, y;
+       unsigned round;
 
        if (BB_BIG_ENDIAN) {
                for (x = 0; x < 25; x++) {
@@ -993,7 +994,7 @@ static void KeccakF(uint64_t *state)
                }
        }
 
-       for (round = 0; round < cKeccakNumberOfRounds; ++round) {
+       for (round = 0; round < KECCAK_NROUNDS; ++round) {
                /* Theta */
                {
                        uint64_t BC[10];
@@ -1003,7 +1004,7 @@ static void KeccakF(uint64_t *state)
                                        ^ state[x + 15] ^ state[x + 20];
                        }
                        /* Using 2x5 vector above eliminates the need to use
-                        * [Mod5[x+N]] index trick below to calculate (x+N) % 5,
+                        * BC[MOD5[x+N]] trick below to fetch BC[(x+N) % 5],
                         * and the code is a bit _smaller_.
                         */
                        for (x = 0; x < 5; ++x) {
@@ -1027,22 +1028,24 @@ static void KeccakF(uint64_t *state)
                if (SHA3_SMALL) {
                        uint64_t t1 = state[1];
                        for (x = 0; x < 24; ++x) {
-                               uint64_t t0 = state[KeccakF_PiLane[x]];
-                               state[KeccakF_PiLane[x]] = rotl64(t1, KeccakF_RotationConstants[x]);
+                               uint64_t t0 = state[KECCAK_PI_LANE[x]];
+                               state[KECCAK_PI_LANE[x]] = rotl64(t1, KECCAK_ROT_CONST[x]);
                                t1 = t0;
                        }
                } else {
                        /* Especially large benefit for 32-bit arch (75% faster):
                         * 64-bit rotations by non-constant usually are SLOW on those.
                         * We resort to unrolling here.
-                        * This optimizes out KeccakF_PiLane[] and KeccakF_RotationConstants[],
+                        * This optimizes out KECCAK_PI_LANE[] and KECCAK_ROT_CONST[],
                         * but generates 300-500 more bytes of code.
                         */
                        uint64_t t0;
                        uint64_t t1 = state[1];
 #define RhoPi_twice(x) \
-                       t0 = state[KeccakF_PiLane[x  ]]; state[KeccakF_PiLane[x  ]] = rotl64(t1, KeccakF_RotationConstants[x  ]); \
-                       t1 = state[KeccakF_PiLane[x+1]]; state[KeccakF_PiLane[x+1]] = rotl64(t0, KeccakF_RotationConstants[x+1]);
+       t0 = state[KECCAK_PI_LANE[x  ]]; \
+       state[KECCAK_PI_LANE[x  ]] = rotl64(t1, KECCAK_ROT_CONST[x  ]); \
+       t1 = state[KECCAK_PI_LANE[x+1]]; \
+       state[KECCAK_PI_LANE[x+1]] = rotl64(t0, KECCAK_ROT_CONST[x+1]);
                        RhoPi_twice(0); RhoPi_twice(2);
                        RhoPi_twice(4); RhoPi_twice(6);
                        RhoPi_twice(8); RhoPi_twice(10);
@@ -1063,8 +1066,8 @@ static void KeccakF(uint64_t *state)
                                BC[4] = state[y + 4];
                                for (x = 0; x < 5; ++x) {
                                        state[y + x] =
-                                           BC[x] ^ ((~BC[KeccakF_Mod5[x + 1]]) &
-                                                    BC[KeccakF_Mod5[x + 2]]);
+                                           BC[x] ^ ((~BC[MOD5[x + 1]]) &
+                                                    BC[MOD5[x + 2]]);
                                }
                        } else {
                                /* 32-bit x86: +50 bytes code, 10% faster */
@@ -1083,9 +1086,9 @@ static void KeccakF(uint64_t *state)
                }
 
                /* Iota */
-               state[0] ^= KeccakF_RoundConstants[round]
-                       | (uint32_t)((KeccakF_RoundConstantBit31 << round) & 0x80000000)
-                       | (uint64_t)((KeccakF_RoundConstantBit63 << round) & 0x80000000) << 32;
+               state[0] ^= KECCAK_IOTA_CONST[round]
+                       | (uint32_t)((KECCAK_IOTA_CONST_bit31 << round) & 0x80000000)
+                       | (uint64_t)((KECCAK_IOTA_CONST_bit63 << round) & 0x80000000) << 32;
        }
 
        if (BB_BIG_ENDIAN) {
@@ -1095,6 +1098,8 @@ static void KeccakF(uint64_t *state)
        }
 }
 
+#undef ARCH_IS_64BIT
+
 void FAST_FUNC sha3_begin(sha3_ctx_t *ctx)
 {
        memset(ctx, 0, sizeof(*ctx));
@@ -1110,19 +1115,19 @@ void FAST_FUNC sha3_hash(sha3_ctx_t *ctx, const void *buf, size_t bytes)
                buffer[ctx->bytes_queued] ^= *data++;
                bytes--;
                ctx->bytes_queued++;
-               if (ctx->bytes_queued == cKeccakR_SizeInBytes) {
+               if (ctx->bytes_queued == KECCAK_IBLK_BYTES) {
                        KeccakF(ctx->state);
                        ctx->bytes_queued = 0;
                }
        }
 
        /* Absorb complete blocks */
-       while (bytes >= cKeccakR_SizeInBytes) {
+       while (bytes >= KECCAK_IBLK_BYTES) {
                /* XOR data onto beginning of state[].
                 * We try to be efficient - operate on word at a time, not byte.
                 * Yet safe wrt unaligned access: can't just use "*(long*)data"...
                 */
-               unsigned count = cKeccakR_SizeInBytes / sizeof(long);
+               unsigned count = KECCAK_IBLK_BYTES / sizeof(long);
                long *buffer = (long*)ctx->state;
                do {
                        long v;
@@ -1132,7 +1137,7 @@ void FAST_FUNC sha3_hash(sha3_ctx_t *ctx, const void *buf, size_t bytes)
                } while (--count);
 
                KeccakF(ctx->state);
-               bytes -= cKeccakR_SizeInBytes;
+               bytes -= KECCAK_IBLK_BYTES;
        }
 
        /* Queue remaining data bytes */
@@ -1148,11 +1153,8 @@ void FAST_FUNC sha3_end(sha3_ctx_t *ctx, uint8_t *hashval)
 {
        /* Padding */
        uint8_t *buffer = (uint8_t*)ctx->state;
-       /* 0 is the number of bits in last, incomplete byte
-        * (that is, zero: we never have incomplete bytes):
-        */
-       buffer[ctx->bytes_queued] ^= 1 << 0;
-       buffer[cKeccakR_SizeInBytes - 1] ^= 0x80;
+       buffer[ctx->bytes_queued]     ^= 1;
+       buffer[KECCAK_IBLK_BYTES - 1] ^= 0x80;
 
        KeccakF(ctx->state);