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authorDenys Vlasenko <vda.linux@googlemail.com>2014-07-25 15:24:13 (GMT)
committer Denys Vlasenko <vda.linux@googlemail.com>2014-07-25 15:24:13 (GMT)
commit2a563ea49a16589f47ed6afe7b22eebef4e3a6d1 (patch)
tree212bbad503c49c6ae0aabaeaef0ab023ca584f39
parenta4d564ad7c24df2da1d8e03a7dd016f0a3d5edbd (diff)
downloadbusybox-master.tar.gz
busybox-master.tar.bz2
sha3: add 32-bit optimized bit-sliced implementationHEADmaster
It is an interesting trick, but so far I only managed to make it work correctly, not to make it faster and/or smaller. The code is ifdefed out for now. Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--libbb/hash_md5_sha.c256
1 files changed, 242 insertions, 14 deletions
diff --git a/libbb/hash_md5_sha.c b/libbb/hash_md5_sha.c
index 3f743ac..dff583a 100644
--- a/libbb/hash_md5_sha.c
+++ b/libbb/hash_md5_sha.c
@@ -926,10 +926,81 @@ void FAST_FUNC sha512_end(sha512_ctx_t *ctx, void *resbuf)
# define SHA3_SMALL CONFIG_SHA3_SMALL
#endif
+#define OPTIMIZE_SHA3_FOR_32 0
+/*
+ * SHA3 can be optimized for 32-bit CPUs with bit-slicing:
+ * every 64-bit word of state[] can be split into two 32-bit words
+ * by even/odd bits. In this form, all rotations of sha3 round
+ * are 32-bit - and there are lots of them.
+ * However, it requires either splitting/combining state words
+ * before/after sha3 round (code does this now)
+ * or shuffling bits before xor'ing them into state and in sha3_end.
+ * Without shuffling, bit-slicing results in -130 bytes of code
+ * and marginal speedup (but of course it gives wrong result).
+ * With shuffling it works, but +260 code bytes, and slower.
+ * Disabled for now:
+ */
+#if 0 /* LONG_MAX == 0x7fffffff */
+# undef OPTIMIZE_SHA3_FOR_32
+# define OPTIMIZE_SHA3_FOR_32 1
+#endif
+
enum {
SHA3_IBLK_BYTES = 72, /* 576 bits / 8 */
};
+#if OPTIMIZE_SHA3_FOR_32
+/* This splits every 64-bit word into a pair of 32-bit words,
+ * even bits go into first word, odd bits go to second one.
+ * The conversion is done in-place.
+ */
+static void split_halves(uint64_t *state)
+{
+ /* Credit: Henry S. Warren, Hacker's Delight, Addison-Wesley, 2002 */
+ uint32_t *s32 = (uint32_t*)state;
+ uint32_t t, x0, x1;
+ int i;
+ for (i = 24; i >= 0; --i) {
+ x0 = s32[0];
+ t = (x0 ^ (x0 >> 1)) & 0x22222222; x0 = x0 ^ t ^ (t << 1);
+ t = (x0 ^ (x0 >> 2)) & 0x0C0C0C0C; x0 = x0 ^ t ^ (t << 2);
+ t = (x0 ^ (x0 >> 4)) & 0x00F000F0; x0 = x0 ^ t ^ (t << 4);
+ t = (x0 ^ (x0 >> 8)) & 0x0000FF00; x0 = x0 ^ t ^ (t << 8);
+ x1 = s32[1];
+ t = (x1 ^ (x1 >> 1)) & 0x22222222; x1 = x1 ^ t ^ (t << 1);
+ t = (x1 ^ (x1 >> 2)) & 0x0C0C0C0C; x1 = x1 ^ t ^ (t << 2);
+ t = (x1 ^ (x1 >> 4)) & 0x00F000F0; x1 = x1 ^ t ^ (t << 4);
+ t = (x1 ^ (x1 >> 8)) & 0x0000FF00; x1 = x1 ^ t ^ (t << 8);
+ *s32++ = (x0 & 0x0000FFFF) | (x1 << 16);
+ *s32++ = (x0 >> 16) | (x1 & 0xFFFF0000);
+ }
+}
+/* The reverse operation */
+static void combine_halves(uint64_t *state)
+{
+ uint32_t *s32 = (uint32_t*)state;
+ uint32_t t, x0, x1;
+ int i;
+ for (i = 24; i >= 0; --i) {
+ x0 = s32[0];
+ x1 = s32[1];
+ t = (x0 & 0x0000FFFF) | (x1 << 16);
+ x1 = (x0 >> 16) | (x1 & 0xFFFF0000);
+ x0 = t;
+ t = (x0 ^ (x0 >> 8)) & 0x0000FF00; x0 = x0 ^ t ^ (t << 8);
+ t = (x0 ^ (x0 >> 4)) & 0x00F000F0; x0 = x0 ^ t ^ (t << 4);
+ t = (x0 ^ (x0 >> 2)) & 0x0C0C0C0C; x0 = x0 ^ t ^ (t << 2);
+ t = (x0 ^ (x0 >> 1)) & 0x22222222; x0 = x0 ^ t ^ (t << 1);
+ *s32++ = x0;
+ t = (x1 ^ (x1 >> 8)) & 0x0000FF00; x1 = x1 ^ t ^ (t << 8);
+ t = (x1 ^ (x1 >> 4)) & 0x00F000F0; x1 = x1 ^ t ^ (t << 4);
+ t = (x1 ^ (x1 >> 2)) & 0x0C0C0C0C; x1 = x1 ^ t ^ (t << 2);
+ t = (x1 ^ (x1 >> 1)) & 0x22222222; x1 = x1 ^ t ^ (t << 1);
+ *s32++ = x1;
+ }
+}
+#endif
+
/*
* In the crypto literature this function is usually called Keccak-f().
*/
@@ -937,6 +1008,164 @@ static void sha3_process_block72(uint64_t *state)
{
enum { NROUNDS = 24 };
+#if OPTIMIZE_SHA3_FOR_32
+ /*
+ static const uint32_t IOTA_CONST_0[NROUNDS] = {
+ 0x00000001UL,
+ 0x00000000UL,
+ 0x00000000UL,
+ 0x00000000UL,
+ 0x00000001UL,
+ 0x00000001UL,
+ 0x00000001UL,
+ 0x00000001UL,
+ 0x00000000UL,
+ 0x00000000UL,
+ 0x00000001UL,
+ 0x00000000UL,
+ 0x00000001UL,
+ 0x00000001UL,
+ 0x00000001UL,
+ 0x00000001UL,
+ 0x00000000UL,
+ 0x00000000UL,
+ 0x00000000UL,
+ 0x00000000UL,
+ 0x00000001UL,
+ 0x00000000UL,
+ 0x00000001UL,
+ 0x00000000UL,
+ };
+ ** bits are in lsb: 0101 0000 1111 0100 1111 0001
+ */
+ uint32_t IOTA_CONST_0bits = (uint32_t)(0x0050f4f1);
+ static const uint32_t IOTA_CONST_1[NROUNDS] = {
+ 0x00000000UL,
+ 0x00000089UL,
+ 0x8000008bUL,
+ 0x80008080UL,
+ 0x0000008bUL,
+ 0x00008000UL,
+ 0x80008088UL,
+ 0x80000082UL,
+ 0x0000000bUL,
+ 0x0000000aUL,
+ 0x00008082UL,
+ 0x00008003UL,
+ 0x0000808bUL,
+ 0x8000000bUL,
+ 0x8000008aUL,
+ 0x80000081UL,
+ 0x80000081UL,
+ 0x80000008UL,
+ 0x00000083UL,
+ 0x80008003UL,
+ 0x80008088UL,
+ 0x80000088UL,
+ 0x00008000UL,
+ 0x80008082UL,
+ };
+
+ uint32_t *const s32 = (uint32_t*)state;
+ unsigned round;
+
+ split_halves(state);
+
+ for (round = 0; round < NROUNDS; round++) {
+ unsigned x;
+
+ /* Theta */
+ {
+ uint32_t BC[20];
+ for (x = 0; x < 10; ++x) {
+ BC[x+10] = BC[x] = s32[x]^s32[x+10]^s32[x+20]^s32[x+30]^s32[x+40];
+ }
+ for (x = 0; x < 10; x += 2) {
+ uint32_t ta, tb;
+ ta = BC[x+8] ^ rotl32(BC[x+3], 1);
+ tb = BC[x+9] ^ BC[x+2];
+ s32[x+0] ^= ta;
+ s32[x+1] ^= tb;
+ s32[x+10] ^= ta;
+ s32[x+11] ^= tb;
+ s32[x+20] ^= ta;
+ s32[x+21] ^= tb;
+ s32[x+30] ^= ta;
+ s32[x+31] ^= tb;
+ s32[x+40] ^= ta;
+ s32[x+41] ^= tb;
+ }
+ }
+ /* RhoPi */
+ {
+ uint32_t t0a,t0b, t1a,t1b;
+ t1a = s32[1*2+0];
+ t1b = s32[1*2+1];
+
+#define RhoPi(PI_LANE, ROT_CONST) \
+ t0a = s32[PI_LANE*2+0];\
+ t0b = s32[PI_LANE*2+1];\
+ if (ROT_CONST & 1) {\
+ s32[PI_LANE*2+0] = rotl32(t1b, ROT_CONST/2+1);\
+ s32[PI_LANE*2+1] = ROT_CONST == 1 ? t1a : rotl32(t1a, ROT_CONST/2+0);\
+ } else {\
+ s32[PI_LANE*2+0] = rotl32(t1a, ROT_CONST/2);\
+ s32[PI_LANE*2+1] = rotl32(t1b, ROT_CONST/2);\
+ }\
+ t1a = t0a; t1b = t0b;
+
+ RhoPi(10, 1)
+ RhoPi( 7, 3)
+ RhoPi(11, 6)
+ RhoPi(17,10)
+ RhoPi(18,15)
+ RhoPi( 3,21)
+ RhoPi( 5,28)
+ RhoPi(16,36)
+ RhoPi( 8,45)
+ RhoPi(21,55)
+ RhoPi(24, 2)
+ RhoPi( 4,14)
+ RhoPi(15,27)
+ RhoPi(23,41)
+ RhoPi(19,56)
+ RhoPi(13, 8)
+ RhoPi(12,25)
+ RhoPi( 2,43)
+ RhoPi(20,62)
+ RhoPi(14,18)
+ RhoPi(22,39)
+ RhoPi( 9,61)
+ RhoPi( 6,20)
+ RhoPi( 1,44)
+#undef RhoPi
+ }
+ /* Chi */
+ for (x = 0; x <= 20; x += 5) {
+ /*
+ * Can write this in terms of uint32 too,
+ * but why? compiler does it automatically.
+ */
+ uint64_t BC0, BC1, BC2, BC3, BC4;
+ BC0 = state[x + 0];
+ BC1 = state[x + 1];
+ BC2 = state[x + 2];
+ state[x + 0] = BC0 ^ ((~BC1) & BC2);
+ BC3 = state[x + 3];
+ state[x + 1] = BC1 ^ ((~BC2) & BC3);
+ BC4 = state[x + 4];
+ state[x + 2] = BC2 ^ ((~BC3) & BC4);
+ state[x + 3] = BC3 ^ ((~BC4) & BC0);
+ state[x + 4] = BC4 ^ ((~BC0) & BC1);
+ }
+ /* Iota */
+ s32[0] ^= IOTA_CONST_0bits & 1;
+ IOTA_CONST_0bits >>= 1;
+ s32[1] ^= IOTA_CONST_1[round];
+ }
+
+ combine_halves(state);
+#else
/* Elements should be 64-bit, but top half is always zero or 0x80000000.
* 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.
@@ -983,7 +1212,7 @@ static void sha3_process_block72(uint64_t *state)
};
/*static const uint8_t MOD5[10] = { 0, 1, 2, 3, 4, 0, 1, 2, 3, 4, };*/
- unsigned x, y;
+ unsigned x;
unsigned round;
if (BB_BIG_ENDIAN) {
@@ -1045,22 +1274,20 @@ static void sha3_process_block72(uint64_t *state)
RhoPi_twice(20); RhoPi_twice(22);
#undef RhoPi_twice
}
-
/* Chi */
- for (y = 0; y <= 20; y += 5) {
+ for (x = 0; x <= 20; x += 5) {
uint64_t BC0, BC1, BC2, BC3, BC4;
- BC0 = state[y + 0];
- BC1 = state[y + 1];
- BC2 = state[y + 2];
- state[y + 0] = BC0 ^ ((~BC1) & BC2);
- BC3 = state[y + 3];
- state[y + 1] = BC1 ^ ((~BC2) & BC3);
- BC4 = state[y + 4];
- state[y + 2] = BC2 ^ ((~BC3) & BC4);
- state[y + 3] = BC3 ^ ((~BC4) & BC0);
- state[y + 4] = BC4 ^ ((~BC0) & BC1);
+ BC0 = state[x + 0];
+ BC1 = state[x + 1];
+ BC2 = state[x + 2];
+ state[x + 0] = BC0 ^ ((~BC1) & BC2);
+ BC3 = state[x + 3];
+ state[x + 1] = BC1 ^ ((~BC2) & BC3);
+ BC4 = state[x + 4];
+ state[x + 2] = BC2 ^ ((~BC3) & BC4);
+ state[x + 3] = BC3 ^ ((~BC4) & BC0);
+ state[x + 4] = BC4 ^ ((~BC0) & BC1);
}
-
/* Iota */
state[0] ^= IOTA_CONST[round]
| (uint32_t)((IOTA_CONST_bit31 << round) & 0x80000000)
@@ -1072,6 +1299,7 @@ static void sha3_process_block72(uint64_t *state)
state[x] = SWAP_LE64(state[x]);
}
}
+#endif
}
void FAST_FUNC sha3_begin(sha3_ctx_t *ctx)