sha3: add 32-bit optimized bit-sliced implementation
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>
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Denys Vlasenko
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@ -926,10 +926,81 @@ void FAST_FUNC sha512_end(sha512_ctx_t *ctx, void *resbuf)
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# define SHA3_SMALL CONFIG_SHA3_SMALL
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#endif
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#define OPTIMIZE_SHA3_FOR_32 0
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/*
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* SHA3 can be optimized for 32-bit CPUs with bit-slicing:
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* every 64-bit word of state[] can be split into two 32-bit words
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* by even/odd bits. In this form, all rotations of sha3 round
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* are 32-bit - and there are lots of them.
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* However, it requires either splitting/combining state words
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* before/after sha3 round (code does this now)
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* or shuffling bits before xor'ing them into state and in sha3_end.
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* Without shuffling, bit-slicing results in -130 bytes of code
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* and marginal speedup (but of course it gives wrong result).
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* With shuffling it works, but +260 code bytes, and slower.
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* Disabled for now:
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*/
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#if 0 /* LONG_MAX == 0x7fffffff */
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# undef OPTIMIZE_SHA3_FOR_32
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# define OPTIMIZE_SHA3_FOR_32 1
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#endif
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enum {
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SHA3_IBLK_BYTES = 72, /* 576 bits / 8 */
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};
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#if OPTIMIZE_SHA3_FOR_32
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/* This splits every 64-bit word into a pair of 32-bit words,
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* even bits go into first word, odd bits go to second one.
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* The conversion is done in-place.
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*/
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static void split_halves(uint64_t *state)
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{
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/* Credit: Henry S. Warren, Hacker's Delight, Addison-Wesley, 2002 */
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uint32_t *s32 = (uint32_t*)state;
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uint32_t t, x0, x1;
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int i;
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for (i = 24; i >= 0; --i) {
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x0 = s32[0];
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t = (x0 ^ (x0 >> 1)) & 0x22222222; x0 = x0 ^ t ^ (t << 1);
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t = (x0 ^ (x0 >> 2)) & 0x0C0C0C0C; x0 = x0 ^ t ^ (t << 2);
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t = (x0 ^ (x0 >> 4)) & 0x00F000F0; x0 = x0 ^ t ^ (t << 4);
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t = (x0 ^ (x0 >> 8)) & 0x0000FF00; x0 = x0 ^ t ^ (t << 8);
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x1 = s32[1];
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t = (x1 ^ (x1 >> 1)) & 0x22222222; x1 = x1 ^ t ^ (t << 1);
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t = (x1 ^ (x1 >> 2)) & 0x0C0C0C0C; x1 = x1 ^ t ^ (t << 2);
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t = (x1 ^ (x1 >> 4)) & 0x00F000F0; x1 = x1 ^ t ^ (t << 4);
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t = (x1 ^ (x1 >> 8)) & 0x0000FF00; x1 = x1 ^ t ^ (t << 8);
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*s32++ = (x0 & 0x0000FFFF) | (x1 << 16);
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*s32++ = (x0 >> 16) | (x1 & 0xFFFF0000);
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}
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}
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/* The reverse operation */
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static void combine_halves(uint64_t *state)
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{
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uint32_t *s32 = (uint32_t*)state;
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uint32_t t, x0, x1;
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int i;
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for (i = 24; i >= 0; --i) {
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x0 = s32[0];
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x1 = s32[1];
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t = (x0 & 0x0000FFFF) | (x1 << 16);
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x1 = (x0 >> 16) | (x1 & 0xFFFF0000);
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x0 = t;
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t = (x0 ^ (x0 >> 8)) & 0x0000FF00; x0 = x0 ^ t ^ (t << 8);
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t = (x0 ^ (x0 >> 4)) & 0x00F000F0; x0 = x0 ^ t ^ (t << 4);
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t = (x0 ^ (x0 >> 2)) & 0x0C0C0C0C; x0 = x0 ^ t ^ (t << 2);
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t = (x0 ^ (x0 >> 1)) & 0x22222222; x0 = x0 ^ t ^ (t << 1);
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*s32++ = x0;
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t = (x1 ^ (x1 >> 8)) & 0x0000FF00; x1 = x1 ^ t ^ (t << 8);
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t = (x1 ^ (x1 >> 4)) & 0x00F000F0; x1 = x1 ^ t ^ (t << 4);
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t = (x1 ^ (x1 >> 2)) & 0x0C0C0C0C; x1 = x1 ^ t ^ (t << 2);
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t = (x1 ^ (x1 >> 1)) & 0x22222222; x1 = x1 ^ t ^ (t << 1);
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*s32++ = x1;
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}
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}
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#endif
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/*
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* In the crypto literature this function is usually called Keccak-f().
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*/
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@ -937,6 +1008,164 @@ static void sha3_process_block72(uint64_t *state)
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{
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enum { NROUNDS = 24 };
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#if OPTIMIZE_SHA3_FOR_32
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/*
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static const uint32_t IOTA_CONST_0[NROUNDS] = {
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0x00000001UL,
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0x00000000UL,
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0x00000000UL,
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0x00000000UL,
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0x00000001UL,
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0x00000001UL,
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0x00000001UL,
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0x00000001UL,
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0x00000000UL,
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0x00000000UL,
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0x00000001UL,
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0x00000000UL,
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0x00000001UL,
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0x00000001UL,
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0x00000001UL,
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0x00000001UL,
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0x00000000UL,
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0x00000000UL,
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0x00000000UL,
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0x00000000UL,
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0x00000001UL,
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0x00000000UL,
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0x00000001UL,
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0x00000000UL,
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};
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** bits are in lsb: 0101 0000 1111 0100 1111 0001
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*/
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uint32_t IOTA_CONST_0bits = (uint32_t)(0x0050f4f1);
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static const uint32_t IOTA_CONST_1[NROUNDS] = {
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0x00000000UL,
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0x00000089UL,
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0x8000008bUL,
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0x80008080UL,
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0x0000008bUL,
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0x00008000UL,
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0x80008088UL,
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0x80000082UL,
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0x0000000bUL,
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0x0000000aUL,
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0x00008082UL,
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0x00008003UL,
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0x0000808bUL,
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0x8000000bUL,
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0x8000008aUL,
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0x80000081UL,
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0x80000081UL,
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0x80000008UL,
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0x00000083UL,
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0x80008003UL,
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0x80008088UL,
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0x80000088UL,
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0x00008000UL,
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0x80008082UL,
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};
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uint32_t *const s32 = (uint32_t*)state;
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unsigned round;
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split_halves(state);
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for (round = 0; round < NROUNDS; round++) {
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unsigned x;
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/* Theta */
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{
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uint32_t BC[20];
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for (x = 0; x < 10; ++x) {
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BC[x+10] = BC[x] = s32[x]^s32[x+10]^s32[x+20]^s32[x+30]^s32[x+40];
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}
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for (x = 0; x < 10; x += 2) {
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uint32_t ta, tb;
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ta = BC[x+8] ^ rotl32(BC[x+3], 1);
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tb = BC[x+9] ^ BC[x+2];
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s32[x+0] ^= ta;
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s32[x+1] ^= tb;
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s32[x+10] ^= ta;
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s32[x+11] ^= tb;
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s32[x+20] ^= ta;
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s32[x+21] ^= tb;
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s32[x+30] ^= ta;
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s32[x+31] ^= tb;
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s32[x+40] ^= ta;
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s32[x+41] ^= tb;
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}
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}
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/* RhoPi */
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{
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uint32_t t0a,t0b, t1a,t1b;
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t1a = s32[1*2+0];
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t1b = s32[1*2+1];
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#define RhoPi(PI_LANE, ROT_CONST) \
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t0a = s32[PI_LANE*2+0];\
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t0b = s32[PI_LANE*2+1];\
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if (ROT_CONST & 1) {\
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s32[PI_LANE*2+0] = rotl32(t1b, ROT_CONST/2+1);\
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s32[PI_LANE*2+1] = ROT_CONST == 1 ? t1a : rotl32(t1a, ROT_CONST/2+0);\
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} else {\
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s32[PI_LANE*2+0] = rotl32(t1a, ROT_CONST/2);\
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s32[PI_LANE*2+1] = rotl32(t1b, ROT_CONST/2);\
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}\
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t1a = t0a; t1b = t0b;
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RhoPi(10, 1)
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RhoPi( 7, 3)
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RhoPi(11, 6)
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RhoPi(17,10)
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RhoPi(18,15)
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RhoPi( 3,21)
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RhoPi( 5,28)
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RhoPi(16,36)
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RhoPi( 8,45)
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RhoPi(21,55)
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RhoPi(24, 2)
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RhoPi( 4,14)
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RhoPi(15,27)
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RhoPi(23,41)
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RhoPi(19,56)
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RhoPi(13, 8)
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RhoPi(12,25)
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RhoPi( 2,43)
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RhoPi(20,62)
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RhoPi(14,18)
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RhoPi(22,39)
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RhoPi( 9,61)
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RhoPi( 6,20)
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RhoPi( 1,44)
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#undef RhoPi
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}
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/* Chi */
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for (x = 0; x <= 20; x += 5) {
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/*
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* Can write this in terms of uint32 too,
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* but why? compiler does it automatically.
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*/
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uint64_t BC0, BC1, BC2, BC3, BC4;
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BC0 = state[x + 0];
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BC1 = state[x + 1];
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BC2 = state[x + 2];
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state[x + 0] = BC0 ^ ((~BC1) & BC2);
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BC3 = state[x + 3];
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state[x + 1] = BC1 ^ ((~BC2) & BC3);
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BC4 = state[x + 4];
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state[x + 2] = BC2 ^ ((~BC3) & BC4);
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state[x + 3] = BC3 ^ ((~BC4) & BC0);
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state[x + 4] = BC4 ^ ((~BC0) & BC1);
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}
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/* Iota */
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s32[0] ^= IOTA_CONST_0bits & 1;
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IOTA_CONST_0bits >>= 1;
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s32[1] ^= IOTA_CONST_1[round];
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}
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combine_halves(state);
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#else
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/* Elements should be 64-bit, but top half is always zero or 0x80000000.
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* We encode 63rd bits in a separate word below.
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* Same is true for 31th bits, which lets us use 16-bit table instead of 64-bit.
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@ -983,7 +1212,7 @@ static void sha3_process_block72(uint64_t *state)
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};
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/*static const uint8_t MOD5[10] = { 0, 1, 2, 3, 4, 0, 1, 2, 3, 4, };*/
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unsigned x, y;
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unsigned x;
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unsigned round;
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if (BB_BIG_ENDIAN) {
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@ -1045,22 +1274,20 @@ static void sha3_process_block72(uint64_t *state)
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RhoPi_twice(20); RhoPi_twice(22);
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#undef RhoPi_twice
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}
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/* Chi */
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for (y = 0; y <= 20; y += 5) {
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for (x = 0; x <= 20; x += 5) {
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uint64_t BC0, BC1, BC2, BC3, BC4;
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BC0 = state[y + 0];
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BC1 = state[y + 1];
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BC2 = state[y + 2];
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state[y + 0] = BC0 ^ ((~BC1) & BC2);
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BC3 = state[y + 3];
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state[y + 1] = BC1 ^ ((~BC2) & BC3);
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BC4 = state[y + 4];
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state[y + 2] = BC2 ^ ((~BC3) & BC4);
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state[y + 3] = BC3 ^ ((~BC4) & BC0);
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state[y + 4] = BC4 ^ ((~BC0) & BC1);
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BC0 = state[x + 0];
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BC1 = state[x + 1];
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BC2 = state[x + 2];
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state[x + 0] = BC0 ^ ((~BC1) & BC2);
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BC3 = state[x + 3];
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state[x + 1] = BC1 ^ ((~BC2) & BC3);
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BC4 = state[x + 4];
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state[x + 2] = BC2 ^ ((~BC3) & BC4);
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state[x + 3] = BC3 ^ ((~BC4) & BC0);
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state[x + 4] = BC4 ^ ((~BC0) & BC1);
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}
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/* Iota */
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state[0] ^= IOTA_CONST[round]
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| (uint32_t)((IOTA_CONST_bit31 << round) & 0x80000000)
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@ -1072,6 +1299,7 @@ static void sha3_process_block72(uint64_t *state)
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state[x] = SWAP_LE64(state[x]);
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}
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}
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#endif
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}
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void FAST_FUNC sha3_begin(sha3_ctx_t *ctx)
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