/* poly1305 implementation using 32 bit * 32 bit = 64 bit multiplication and 64 bit addition */ #if defined(_MSC_VER) # define POLY1305_NOINLINE __declspec(noinline) #elif defined(__clang__) || defined(__GNUC__) # define POLY1305_NOINLINE __attribute__((noinline)) #else # define POLY1305_NOINLINE #endif #include "private/common.h" #define poly1305_block_size 16 /* 17 + sizeof(unsigned long long) + 14*sizeof(unsigned long) */ typedef struct poly1305_state_internal_t { unsigned long r[5]; unsigned long h[5]; unsigned long pad[4]; unsigned long long leftover; unsigned char buffer[poly1305_block_size]; unsigned char final; } poly1305_state_internal_t; static void poly1305_init(poly1305_state_internal_t *st, const unsigned char key[32]) { /* r &= 0xffffffc0ffffffc0ffffffc0fffffff - wiped after finalization */ st->r[0] = (LOAD32_LE(&key[0])) & 0x3ffffff; st->r[1] = (LOAD32_LE(&key[3]) >> 2) & 0x3ffff03; st->r[2] = (LOAD32_LE(&key[6]) >> 4) & 0x3ffc0ff; st->r[3] = (LOAD32_LE(&key[9]) >> 6) & 0x3f03fff; st->r[4] = (LOAD32_LE(&key[12]) >> 8) & 0x00fffff; /* h = 0 */ st->h[0] = 0; st->h[1] = 0; st->h[2] = 0; st->h[3] = 0; st->h[4] = 0; /* save pad for later */ st->pad[0] = LOAD32_LE(&key[16]); st->pad[1] = LOAD32_LE(&key[20]); st->pad[2] = LOAD32_LE(&key[24]); st->pad[3] = LOAD32_LE(&key[28]); st->leftover = 0; st->final = 0; } static void poly1305_blocks(poly1305_state_internal_t *st, const unsigned char *m, unsigned long long bytes) { const unsigned long hibit = (st->final) ? 0UL : (1UL << 24); /* 1 << 128 */ unsigned long r0, r1, r2, r3, r4; unsigned long s1, s2, s3, s4; unsigned long h0, h1, h2, h3, h4; unsigned long long d0, d1, d2, d3, d4; unsigned long c; r0 = st->r[0]; r1 = st->r[1]; r2 = st->r[2]; r3 = st->r[3]; r4 = st->r[4]; s1 = r1 * 5; s2 = r2 * 5; s3 = r3 * 5; s4 = r4 * 5; h0 = st->h[0]; h1 = st->h[1]; h2 = st->h[2]; h3 = st->h[3]; h4 = st->h[4]; while (bytes >= poly1305_block_size) { /* h += m[i] */ h0 += (LOAD32_LE(m + 0)) & 0x3ffffff; h1 += (LOAD32_LE(m + 3) >> 2) & 0x3ffffff; h2 += (LOAD32_LE(m + 6) >> 4) & 0x3ffffff; h3 += (LOAD32_LE(m + 9) >> 6) & 0x3ffffff; h4 += (LOAD32_LE(m + 12) >> 8) | hibit; /* h *= r */ d0 = ((unsigned long long) h0 * r0) + ((unsigned long long) h1 * s4) + ((unsigned long long) h2 * s3) + ((unsigned long long) h3 * s2) + ((unsigned long long) h4 * s1); d1 = ((unsigned long long) h0 * r1) + ((unsigned long long) h1 * r0) + ((unsigned long long) h2 * s4) + ((unsigned long long) h3 * s3) + ((unsigned long long) h4 * s2); d2 = ((unsigned long long) h0 * r2) + ((unsigned long long) h1 * r1) + ((unsigned long long) h2 * r0) + ((unsigned long long) h3 * s4) + ((unsigned long long) h4 * s3); d3 = ((unsigned long long) h0 * r3) + ((unsigned long long) h1 * r2) + ((unsigned long long) h2 * r1) + ((unsigned long long) h3 * r0) + ((unsigned long long) h4 * s4); d4 = ((unsigned long long) h0 * r4) + ((unsigned long long) h1 * r3) + ((unsigned long long) h2 * r2) + ((unsigned long long) h3 * r1) + ((unsigned long long) h4 * r0); /* (partial) h %= p */ c = (unsigned long) (d0 >> 26); h0 = (unsigned long) d0 & 0x3ffffff; d1 += c; c = (unsigned long) (d1 >> 26); h1 = (unsigned long) d1 & 0x3ffffff; d2 += c; c = (unsigned long) (d2 >> 26); h2 = (unsigned long) d2 & 0x3ffffff; d3 += c; c = (unsigned long) (d3 >> 26); h3 = (unsigned long) d3 & 0x3ffffff; d4 += c; c = (unsigned long) (d4 >> 26); h4 = (unsigned long) d4 & 0x3ffffff; h0 += c * 5; c = (h0 >> 26); h0 = h0 & 0x3ffffff; h1 += c; m += poly1305_block_size; bytes -= poly1305_block_size; } st->h[0] = h0; st->h[1] = h1; st->h[2] = h2; st->h[3] = h3; st->h[4] = h4; } static POLY1305_NOINLINE void poly1305_finish(poly1305_state_internal_t *st, unsigned char mac[16]) { unsigned long h0, h1, h2, h3, h4, c; unsigned long g0, g1, g2, g3, g4; unsigned long long f; unsigned long mask; /* process the remaining block */ if (st->leftover) { unsigned long long i = st->leftover; st->buffer[i++] = 1; for (; i < poly1305_block_size; i++) { st->buffer[i] = 0; } st->final = 1; poly1305_blocks(st, st->buffer, poly1305_block_size); } /* fully carry h */ h0 = st->h[0]; h1 = st->h[1]; h2 = st->h[2]; h3 = st->h[3]; h4 = st->h[4]; c = h1 >> 26; h1 = h1 & 0x3ffffff; h2 += c; c = h2 >> 26; h2 = h2 & 0x3ffffff; h3 += c; c = h3 >> 26; h3 = h3 & 0x3ffffff; h4 += c; c = h4 >> 26; h4 = h4 & 0x3ffffff; h0 += c * 5; c = h0 >> 26; h0 = h0 & 0x3ffffff; h1 += c; /* compute h + -p */ g0 = h0 + 5; c = g0 >> 26; g0 &= 0x3ffffff; g1 = h1 + c; c = g1 >> 26; g1 &= 0x3ffffff; g2 = h2 + c; c = g2 >> 26; g2 &= 0x3ffffff; g3 = h3 + c; c = g3 >> 26; g3 &= 0x3ffffff; g4 = h4 + c - (1UL << 26); /* select h if h < p, or h + -p if h >= p */ mask = (g4 >> ((sizeof(unsigned long) * 8) - 1)) - 1; g0 &= mask; g1 &= mask; g2 &= mask; g3 &= mask; g4 &= mask; mask = ~mask; h0 = (h0 & mask) | g0; h1 = (h1 & mask) | g1; h2 = (h2 & mask) | g2; h3 = (h3 & mask) | g3; h4 = (h4 & mask) | g4; /* h = h % (2^128) */ h0 = ((h0) | (h1 << 26)) & 0xffffffff; h1 = ((h1 >> 6) | (h2 << 20)) & 0xffffffff; h2 = ((h2 >> 12) | (h3 << 14)) & 0xffffffff; h3 = ((h3 >> 18) | (h4 << 8)) & 0xffffffff; /* mac = (h + pad) % (2^128) */ f = (unsigned long long) h0 + st->pad[0]; h0 = (unsigned long) f; f = (unsigned long long) h1 + st->pad[1] + (f >> 32); h1 = (unsigned long) f; f = (unsigned long long) h2 + st->pad[2] + (f >> 32); h2 = (unsigned long) f; f = (unsigned long long) h3 + st->pad[3] + (f >> 32); h3 = (unsigned long) f; STORE32_LE(mac + 0, (uint32_t) h0); STORE32_LE(mac + 4, (uint32_t) h1); STORE32_LE(mac + 8, (uint32_t) h2); STORE32_LE(mac + 12, (uint32_t) h3); /* zero out the state */ sodium_memzero((void *) st, sizeof *st); }