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/*
* Public Domain poly1305 from Andrew Moon
* poly1305-donna-unrolled.c from https://github.com/floodyberry/poly1305-donna
*/
/* $OpenBSD: poly1305.c,v 1.3 2013/12/19 22:57:13 djm Exp $ */
#include <sys/types.h>
#include <stdint.h>
#include "poly1305.h"
#define mul32x32_64(a,b) ((uint64_t)(a) * (b))
#define U8TO32_LE(p) \
(((uint32_t)((p)[0])) | \
((uint32_t)((p)[1]) << 8) | \
((uint32_t)((p)[2]) << 16) | \
((uint32_t)((p)[3]) << 24))
#define U32TO8_LE(p, v) \
do { \
(p)[0] = (uint8_t)((v)); \
(p)[1] = (uint8_t)((v) >> 8); \
(p)[2] = (uint8_t)((v) >> 16); \
(p)[3] = (uint8_t)((v) >> 24); \
} while (0)
void
poly1305_auth(unsigned char out[POLY1305_TAGLEN], const unsigned char *m, size_t inlen, const unsigned char key[POLY1305_KEYLEN]) {
uint32_t t0,t1,t2,t3;
uint32_t h0,h1,h2,h3,h4;
uint32_t r0,r1,r2,r3,r4;
uint32_t s1,s2,s3,s4;
uint32_t b, nb;
size_t j;
uint64_t t[5];
uint64_t f0,f1,f2,f3;
uint32_t g0,g1,g2,g3,g4;
uint64_t c;
unsigned char mp[16];
/* clamp key */
t0 = U8TO32_LE(key+0);
t1 = U8TO32_LE(key+4);
t2 = U8TO32_LE(key+8);
t3 = U8TO32_LE(key+12);
/* precompute multipliers */
r0 = t0 & 0x3ffffff; t0 >>= 26; t0 |= t1 << 6;
r1 = t0 & 0x3ffff03; t1 >>= 20; t1 |= t2 << 12;
r2 = t1 & 0x3ffc0ff; t2 >>= 14; t2 |= t3 << 18;
r3 = t2 & 0x3f03fff; t3 >>= 8;
r4 = t3 & 0x00fffff;
s1 = r1 * 5;
s2 = r2 * 5;
s3 = r3 * 5;
s4 = r4 * 5;
/* init state */
h0 = 0;
h1 = 0;
h2 = 0;
h3 = 0;
h4 = 0;
/* full blocks */
if (inlen < 16) goto poly1305_donna_atmost15bytes;
poly1305_donna_16bytes:
m += 16;
inlen -= 16;
t0 = U8TO32_LE(m-16);
t1 = U8TO32_LE(m-12);
t2 = U8TO32_LE(m-8);
t3 = U8TO32_LE(m-4);
h0 += t0 & 0x3ffffff;
h1 += ((((uint64_t)t1 << 32) | t0) >> 26) & 0x3ffffff;
h2 += ((((uint64_t)t2 << 32) | t1) >> 20) & 0x3ffffff;
h3 += ((((uint64_t)t3 << 32) | t2) >> 14) & 0x3ffffff;
h4 += (t3 >> 8) | (1 << 24);
poly1305_donna_mul:
t[0] = mul32x32_64(h0,r0) + mul32x32_64(h1,s4) + mul32x32_64(h2,s3) + mul32x32_64(h3,s2) + mul32x32_64(h4,s1);
t[1] = mul32x32_64(h0,r1) + mul32x32_64(h1,r0) + mul32x32_64(h2,s4) + mul32x32_64(h3,s3) + mul32x32_64(h4,s2);
t[2] = mul32x32_64(h0,r2) + mul32x32_64(h1,r1) + mul32x32_64(h2,r0) + mul32x32_64(h3,s4) + mul32x32_64(h4,s3);
t[3] = mul32x32_64(h0,r3) + mul32x32_64(h1,r2) + mul32x32_64(h2,r1) + mul32x32_64(h3,r0) + mul32x32_64(h4,s4);
t[4] = mul32x32_64(h0,r4) + mul32x32_64(h1,r3) + mul32x32_64(h2,r2) + mul32x32_64(h3,r1) + mul32x32_64(h4,r0);
h0 = (uint32_t)t[0] & 0x3ffffff; c = (t[0] >> 26);
t[1] += c; h1 = (uint32_t)t[1] & 0x3ffffff; b = (uint32_t)(t[1] >> 26);
t[2] += b; h2 = (uint32_t)t[2] & 0x3ffffff; b = (uint32_t)(t[2] >> 26);
t[3] += b; h3 = (uint32_t)t[3] & 0x3ffffff; b = (uint32_t)(t[3] >> 26);
t[4] += b; h4 = (uint32_t)t[4] & 0x3ffffff; b = (uint32_t)(t[4] >> 26);
h0 += b * 5;
if (inlen >= 16) goto poly1305_donna_16bytes;
/* final bytes */
poly1305_donna_atmost15bytes:
if (!inlen) goto poly1305_donna_finish;
for (j = 0; j < inlen; j++) mp[j] = m[j];
mp[j++] = 1;
for (; j < 16; j++) mp[j] = 0;
inlen = 0;
t0 = U8TO32_LE(mp+0);
t1 = U8TO32_LE(mp+4);
t2 = U8TO32_LE(mp+8);
t3 = U8TO32_LE(mp+12);
h0 += t0 & 0x3ffffff;
h1 += ((((uint64_t)t1 << 32) | t0) >> 26) & 0x3ffffff;
h2 += ((((uint64_t)t2 << 32) | t1) >> 20) & 0x3ffffff;
h3 += ((((uint64_t)t3 << 32) | t2) >> 14) & 0x3ffffff;
h4 += (t3 >> 8);
goto poly1305_donna_mul;
poly1305_donna_finish:
b = h0 >> 26; h0 = h0 & 0x3ffffff;
h1 += b; b = h1 >> 26; h1 = h1 & 0x3ffffff;
h2 += b; b = h2 >> 26; h2 = h2 & 0x3ffffff;
h3 += b; b = h3 >> 26; h3 = h3 & 0x3ffffff;
h4 += b; b = h4 >> 26; h4 = h4 & 0x3ffffff;
h0 += b * 5; b = h0 >> 26; h0 = h0 & 0x3ffffff;
h1 += b;
g0 = h0 + 5; b = g0 >> 26; g0 &= 0x3ffffff;
g1 = h1 + b; b = g1 >> 26; g1 &= 0x3ffffff;
g2 = h2 + b; b = g2 >> 26; g2 &= 0x3ffffff;
g3 = h3 + b; b = g3 >> 26; g3 &= 0x3ffffff;
g4 = h4 + b - (1 << 26);
b = (g4 >> 31) - 1;
nb = ~b;
h0 = (h0 & nb) | (g0 & b);
h1 = (h1 & nb) | (g1 & b);
h2 = (h2 & nb) | (g2 & b);
h3 = (h3 & nb) | (g3 & b);
h4 = (h4 & nb) | (g4 & b);
f0 = ((h0 ) | (h1 << 26)) + (uint64_t)U8TO32_LE(&key[16]);
f1 = ((h1 >> 6) | (h2 << 20)) + (uint64_t)U8TO32_LE(&key[20]);
f2 = ((h2 >> 12) | (h3 << 14)) + (uint64_t)U8TO32_LE(&key[24]);
f3 = ((h3 >> 18) | (h4 << 8)) + (uint64_t)U8TO32_LE(&key[28]);
U32TO8_LE(&out[ 0], f0); f1 += (f0 >> 32);
U32TO8_LE(&out[ 4], f1); f2 += (f1 >> 32);
U32TO8_LE(&out[ 8], f2); f3 += (f2 >> 32);
U32TO8_LE(&out[12], f3);
}
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