ref: c8b1153aeecbda4e0d33354df259a9520c107728
dir: /libsec/poly1305.c/
#include "os.h" #include <libsec.h> /* poly1305 implementation using 32 bit * 32 bit = 64 bit multiplication and 64 bit addition derived from http://github.com/floodberry/poly1305-donna */ #define U8TO32(p) ((u32int)(p)[0] | (u32int)(p)[1]<<8 | (u32int)(p)[2]<<16 | (u32int)(p)[3]<<24) #define U32TO8(p, v) (p)[0]=(v), (p)[1]=(v)>>8, (p)[2]=(v)>>16, (p)[3]=(v)>>24 /* (r,s) = (key[0:15],key[16:31]), the one time key */ DigestState* poly1305(uchar *m, ulong len, uchar *key, ulong klen, uchar *digest, DigestState *s) { u32int r0,r1,r2,r3,r4, s1,s2,s3,s4, h0,h1,h2,h3,h4, g0,g1,g2,g3,g4; u64int d0,d1,d2,d3,d4, f; u32int hibit, mask, c; if(s == nil){ s = malloc(sizeof(*s)); if(s == nil) return nil; memset(s, 0, sizeof(*s)); s->malloced = 1; } if(s->seeded == 0){ assert(klen == 32); /* r &= 0xffffffc0ffffffc0ffffffc0fffffff */ s->state[0] = (U8TO32(&key[ 0]) ) & 0x3ffffff; s->state[1] = (U8TO32(&key[ 3]) >> 2) & 0x3ffff03; s->state[2] = (U8TO32(&key[ 6]) >> 4) & 0x3ffc0ff; s->state[3] = (U8TO32(&key[ 9]) >> 6) & 0x3f03fff; s->state[4] = (U8TO32(&key[12]) >> 8) & 0x00fffff; /* h = 0 */ s->state[5] = 0; s->state[6] = 0; s->state[7] = 0; s->state[8] = 0; s->state[9] = 0; /* save pad for later */ s->state[10] = U8TO32(&key[16]); s->state[11] = U8TO32(&key[20]); s->state[12] = U8TO32(&key[24]); s->state[13] = U8TO32(&key[28]); s->seeded = 1; } if(s->blen){ c = 16 - s->blen; if(c > len) c = len; memmove(s->buf + s->blen, m, c); len -= c, m += c; s->blen += c; if(s->blen == 16){ s->blen = 0; poly1305(s->buf, 16, key, klen, nil, s); } else if(len == 0){ m = s->buf; len = s->blen; s->blen = 0; } } r0 = s->state[0]; r1 = s->state[1]; r2 = s->state[2]; r3 = s->state[3]; r4 = s->state[4]; h0 = s->state[5]; h1 = s->state[6]; h2 = s->state[7]; h3 = s->state[8]; h4 = s->state[9]; s1 = r1 * 5; s2 = r2 * 5; s3 = r3 * 5; s4 = r4 * 5; hibit = 1<<24; /* 1<<128 */ while(len >= 16){ Block: /* h += m[i] */ h0 += (U8TO32(&m[0]) ) & 0x3ffffff; h1 += (U8TO32(&m[3]) >> 2) & 0x3ffffff; h2 += (U8TO32(&m[6]) >> 4) & 0x3ffffff; h3 += (U8TO32(&m[9]) >> 6) & 0x3ffffff; h4 += (U8TO32(&m[12])>> 8) | hibit; /* h *= r */ d0 = ((u64int)h0 * r0) + ((u64int)h1 * s4) + ((u64int)h2 * s3) + ((u64int)h3 * s2) + ((u64int)h4 * s1); d1 = ((u64int)h0 * r1) + ((u64int)h1 * r0) + ((u64int)h2 * s4) + ((u64int)h3 * s3) + ((u64int)h4 * s2); d2 = ((u64int)h0 * r2) + ((u64int)h1 * r1) + ((u64int)h2 * r0) + ((u64int)h3 * s4) + ((u64int)h4 * s3); d3 = ((u64int)h0 * r3) + ((u64int)h1 * r2) + ((u64int)h2 * r1) + ((u64int)h3 * r0) + ((u64int)h4 * s4); d4 = ((u64int)h0 * r4) + ((u64int)h1 * r3) + ((u64int)h2 * r2) + ((u64int)h3 * r1) + ((u64int)h4 * r0); /* (partial) h %= p */ c = (u32int)(d0 >> 26); h0 = (u32int)d0 & 0x3ffffff; d1 += c; c = (u32int)(d1 >> 26); h1 = (u32int)d1 & 0x3ffffff; d2 += c; c = (u32int)(d2 >> 26); h2 = (u32int)d2 & 0x3ffffff; d3 += c; c = (u32int)(d3 >> 26); h3 = (u32int)d3 & 0x3ffffff; d4 += c; c = (u32int)(d4 >> 26); h4 = (u32int)d4 & 0x3ffffff; h0 += c * 5; c = (h0 >> 26); h0 = h0 & 0x3ffffff; h1 += c; len -= 16, m += 16; } if(len){ s->blen = len; memmove(s->buf, m, len); } if(digest == nil){ s->state[5] = h0; s->state[6] = h1; s->state[7] = h2; s->state[8] = h3; s->state[9] = h4; return s; } if(len){ m = s->buf; m[len++] = 1; while(len < 16) m[len++] = 0; hibit = 0; goto Block; } 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 - (1 << 26); /* select h if h < p, or h + -p if h >= p */ mask = (g4 >> 31) - 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); h1 = (h1 >> 6) | (h2 << 20); h2 = (h2 >> 12) | (h3 << 14); h3 = (h3 >> 18) | (h4 << 8); /* digest = (h + pad) % (2^128) */ f = (u64int)h0 + s->state[10] ; h0 = (u32int)f; f = (u64int)h1 + s->state[11] + (f >> 32); h1 = (u32int)f; f = (u64int)h2 + s->state[12] + (f >> 32); h2 = (u32int)f; f = (u64int)h3 + s->state[13] + (f >> 32); h3 = (u32int)f; U32TO8(&digest[0], h0); U32TO8(&digest[4], h1); U32TO8(&digest[8], h2); U32TO8(&digest[12], h3); if(s->malloced){ memset(s, 0, sizeof(*s)); free(s); return nil; } memset(s, 0, sizeof(*s)); return nil; }