crypto/openssh/poly1305.c

   1 /*
   2  * Public Domain poly1305 from Andrew Moon
   3  * poly1305-donna-unrolled.c from https://github.com/floodyberry/poly1305-donna
   4  */
   5
   6 /* $OpenBSD: poly1305.c,v 1.3 2013/12/19 22:57:13 djm Exp $ */
   7
   8 #include "includes.h"
   9
  10 #include <sys/types.h>
  11 #ifdef HAVE_STDINT_H
  12 # include <stdint.h>
  13 #endif
  14
  15 #include "poly1305.h"
  16
  17 #define mul32x32_64(a,b) ((uint64_t)(a) * (b))
  18
  19 #define U8TO32_LE(p) \
  20         (((uint32_t)((p)[0])) | \
  21          ((uint32_t)((p)[1]) <<  8) | \
  22          ((uint32_t)((p)[2]) << 16) | \
  23          ((uint32_t)((p)[3]) << 24))
  24
  25 #define U32TO8_LE(p, v) \
  26         do { \
  27                 (p)[0] = (uint8_t)((v)); \
  28                 (p)[1] = (uint8_t)((v) >>  8); \
  29                 (p)[2] = (uint8_t)((v) >> 16); \
  30                 (p)[3] = (uint8_t)((v) >> 24); \
  31         } while (0)
  32
  33 void
  34 poly1305_auth(unsigned char out[POLY1305_TAGLEN], const unsigned char *m, size_t inlen, const unsigned char key[POLY1305_KEYLEN]) {
  35         uint32_t t0,t1,t2,t3;
  36         uint32_t h0,h1,h2,h3,h4;
  37         uint32_t r0,r1,r2,r3,r4;
  38         uint32_t s1,s2,s3,s4;
  39         uint32_t b, nb;
  40         size_t j;
  41         uint64_t t[5];
  42         uint64_t f0,f1,f2,f3;
  43         uint32_t g0,g1,g2,g3,g4;
  44         uint64_t c;
  45         unsigned char mp[16];
  46
  47         /* clamp key */
  48         t0 = U8TO32_LE(key+0);
  49         t1 = U8TO32_LE(key+4);
  50         t2 = U8TO32_LE(key+8);
  51         t3 = U8TO32_LE(key+12);
  52
  53         /* precompute multipliers */
  54         r0 = t0 & 0x3ffffff; t0 >>= 26; t0 |= t1 << 6;
  55         r1 = t0 & 0x3ffff03; t1 >>= 20; t1 |= t2 << 12;
  56         r2 = t1 & 0x3ffc0ff; t2 >>= 14; t2 |= t3 << 18;
  57         r3 = t2 & 0x3f03fff; t3 >>= 8;
  58         r4 = t3 & 0x00fffff;
  59
  60         s1 = r1 * 5;
  61         s2 = r2 * 5;
  62         s3 = r3 * 5;
  63         s4 = r4 * 5;
  64
  65         /* init state */
  66         h0 = 0;
  67         h1 = 0;
  68         h2 = 0;
  69         h3 = 0;
  70         h4 = 0;
  71
  72         /* full blocks */
  73         if (inlen < 16) goto poly1305_donna_atmost15bytes;
  74 poly1305_donna_16bytes:
  75         m += 16;
  76         inlen -= 16;
  77
  78         t0 = U8TO32_LE(m-16);
  79         t1 = U8TO32_LE(m-12);
  80         t2 = U8TO32_LE(m-8);
  81         t3 = U8TO32_LE(m-4);
  82
  83         h0 += t0 & 0x3ffffff;
  84         h1 += ((((uint64_t)t1 << 32) | t0) >> 26) & 0x3ffffff;
  85         h2 += ((((uint64_t)t2 << 32) | t1) >> 20) & 0x3ffffff;
  86         h3 += ((((uint64_t)t3 << 32) | t2) >> 14) & 0x3ffffff;
  87         h4 += (t3 >> 8) | (1 << 24);
  88
  89
  90 poly1305_donna_mul:
  91         t[0]  = mul32x32_64(h0,r0) + mul32x32_64(h1,s4) + mul32x32_64(h2,s3) + mul32x32_64(h3,s2) + mul32x32_64(h4,s1);
  92         t[1]  = mul32x32_64(h0,r1) + mul32x32_64(h1,r0) + mul32x32_64(h2,s4) + mul32x32_64(h3,s3) + mul32x32_64(h4,s2);
  93         t[2]  = mul32x32_64(h0,r2) + mul32x32_64(h1,r1) + mul32x32_64(h2,r0) + mul32x32_64(h3,s4) + mul32x32_64(h4,s3);
  94         t[3]  = mul32x32_64(h0,r3) + mul32x32_64(h1,r2) + mul32x32_64(h2,r1) + mul32x32_64(h3,r0) + mul32x32_64(h4,s4);
  95         t[4]  = mul32x32_64(h0,r4) + mul32x32_64(h1,r3) + mul32x32_64(h2,r2) + mul32x32_64(h3,r1) + mul32x32_64(h4,r0);
  96
  97                         h0 = (uint32_t)t[0] & 0x3ffffff; c =           (t[0] >> 26);
  98         t[1] += c;      h1 = (uint32_t)t[1] & 0x3ffffff; b = (uint32_t)(t[1] >> 26);
  99         t[2] += b;      h2 = (uint32_t)t[2] & 0x3ffffff; b = (uint32_t)(t[2] >> 26);
 100         t[3] += b;      h3 = (uint32_t)t[3] & 0x3ffffff; b = (uint32_t)(t[3] >> 26);
 101         t[4] += b;      h4 = (uint32_t)t[4] & 0x3ffffff; b = (uint32_t)(t[4] >> 26);
 102         h0 += b * 5;
 103
 104         if (inlen >= 16) goto poly1305_donna_16bytes;
 105
 106         /* final bytes */
 107 poly1305_donna_atmost15bytes:
 108         if (!inlen) goto poly1305_donna_finish;
 109
 110         for (j = 0; j < inlen; j++) mp[j] = m[j];
 111         mp[j++] = 1;
 112         for (; j < 16; j++)     mp[j] = 0;
 113         inlen = 0;
 114
 115         t0 = U8TO32_LE(mp+0);
 116         t1 = U8TO32_LE(mp+4);
 117         t2 = U8TO32_LE(mp+8);
 118         t3 = U8TO32_LE(mp+12);
 119
 120         h0 += t0 & 0x3ffffff;
 121         h1 += ((((uint64_t)t1 << 32) | t0) >> 26) & 0x3ffffff;
 122         h2 += ((((uint64_t)t2 << 32) | t1) >> 20) & 0x3ffffff;
 123         h3 += ((((uint64_t)t3 << 32) | t2) >> 14) & 0x3ffffff;
 124         h4 += (t3 >> 8);
 125
 126         goto poly1305_donna_mul;
 127
 128 poly1305_donna_finish:
 129                      b = h0 >> 26; h0 = h0 & 0x3ffffff;
 130         h1 +=     b; b = h1 >> 26; h1 = h1 & 0x3ffffff;
 131         h2 +=     b; b = h2 >> 26; h2 = h2 & 0x3ffffff;
 132         h3 +=     b; b = h3 >> 26; h3 = h3 & 0x3ffffff;
 133         h4 +=     b; b = h4 >> 26; h4 = h4 & 0x3ffffff;
 134         h0 += b * 5; b = h0 >> 26; h0 = h0 & 0x3ffffff;
 135         h1 +=     b;
 136
 137         g0 = h0 + 5; b = g0 >> 26; g0 &= 0x3ffffff;
 138         g1 = h1 + b; b = g1 >> 26; g1 &= 0x3ffffff;
 139         g2 = h2 + b; b = g2 >> 26; g2 &= 0x3ffffff;
 140         g3 = h3 + b; b = g3 >> 26; g3 &= 0x3ffffff;
 141         g4 = h4 + b - (1 << 26);
 142
 143         b = (g4 >> 31) - 1;
 144         nb = ~b;
 145         h0 = (h0 & nb) | (g0 & b);
 146         h1 = (h1 & nb) | (g1 & b);
 147         h2 = (h2 & nb) | (g2 & b);
 148         h3 = (h3 & nb) | (g3 & b);
 149         h4 = (h4 & nb) | (g4 & b);
 150
 151         f0 = ((h0      ) | (h1 << 26)) + (uint64_t)U8TO32_LE(&key[16]);
 152         f1 = ((h1 >>  6) | (h2 << 20)) + (uint64_t)U8TO32_LE(&key[20]);
 153         f2 = ((h2 >> 12) | (h3 << 14)) + (uint64_t)U8TO32_LE(&key[24]);
 154         f3 = ((h3 >> 18) | (h4 <<  8)) + (uint64_t)U8TO32_LE(&key[28]);
 155
 156         U32TO8_LE(&out[ 0], f0); f1 += (f0 >> 32);
 157         U32TO8_LE(&out[ 4], f1); f2 += (f1 >> 32);
 158         U32TO8_LE(&out[ 8], f2); f3 += (f2 >> 32);
 159         U32TO8_LE(&out[12], f3);
 160 }