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/*
poly1305 implementation using 64 bit * 64 bit = 128 bit multiplication and 128 bit addition
assumes the existence of uint64_t and uint128_t
*/
#include "config.h"
#include "poly1305.h"
enum {
POLY1305_BLOCK_SIZE = 16
};
#if defined(_MSC_VER)
#include <intrin.h>
typedef struct uint128_t {
unsigned long long lo;
unsigned long long hi;
} uint128_t;
#define POLY1305_NOINLINE __declspec(noinline)
#elif defined(__GNUC__)
#pragma GCC system_header
#if defined(__SIZEOF_INT128__)
typedef unsigned __int128 uint128_t;
#else
typedef unsigned uint128_t __attribute__((mode(TI)));
#endif
#define POLY1305_NOINLINE __attribute__((noinline))
#endif
typedef struct poly1305_state_ref_t {
uint64_t r[3];
uint64_t h[3];
uint64_t pad[2];
unsigned char final;
} poly1305_state_ref_t;
/* interpret eight 8 bit unsigned integers as a 64 bit unsigned integer in little endian */
static uint64_t
U8TO64(const unsigned char *p) {
return
((uint64_t)p[0] ) |
((uint64_t)p[1] << 8) |
((uint64_t)p[2] << 16) |
((uint64_t)p[3] << 24) |
((uint64_t)p[4] << 32) |
((uint64_t)p[5] << 40) |
((uint64_t)p[6] << 48) |
((uint64_t)p[7] << 56);
}
/* store a 64 bit unsigned integer as eight 8 bit unsigned integers in little endian */
static void
U64TO8(unsigned char *p, uint64_t v) {
p[0] = (unsigned char)(v ) & 0xff;
p[1] = (unsigned char)(v >> 8) & 0xff;
p[2] = (unsigned char)(v >> 16) & 0xff;
p[3] = (unsigned char)(v >> 24) & 0xff;
p[4] = (unsigned char)(v >> 32) & 0xff;
p[5] = (unsigned char)(v >> 40) & 0xff;
p[6] = (unsigned char)(v >> 48) & 0xff;
p[7] = (unsigned char)(v >> 56) & 0xff;
}
size_t
poly1305_block_size_ref(void) {
return POLY1305_BLOCK_SIZE;
}
void
poly1305_init_ext_ref(void *state, const poly1305_key *key, size_t bytes_hint) {
poly1305_state_ref_t *st = (poly1305_state_ref_t *)state;
uint64_t t0, t1;
/* bytes_hint not used */
(void)bytes_hint;
/* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
t0 = U8TO64(&key->b[0]);
t1 = U8TO64(&key->b[8]);
st->r[0] = ( t0 ) & 0xffc0fffffff;
st->r[1] = ((t0 >> 44) | (t1 << 20)) & 0xfffffc0ffff;
st->r[2] = ((t1 >> 24) ) & 0x00ffffffc0f;
/* h = 0 */
st->h[0] = 0;
st->h[1] = 0;
st->h[2] = 0;
/* save pad for later */
st->pad[0] = U8TO64(&key->b[16]);
st->pad[1] = U8TO64(&key->b[24]);
st->final = 0;
}
void
poly1305_blocks_ref(void *state, const unsigned char *in, size_t inlen) {
poly1305_state_ref_t *st = (poly1305_state_ref_t *)state;
const uint64_t hibit = (st->final) ? 0 : ((uint64_t)1 << 40); /* 1 << 128 */
uint64_t r0,r1,r2;
uint64_t s1,s2;
uint64_t h0,h1,h2;
uint64_t c;
uint128_t d0,d1,d2;
r0 = st->r[0];
r1 = st->r[1];
r2 = st->r[2];
s1 = r1 * (5 << 2);
s2 = r2 * (5 << 2);
h0 = st->h[0];
h1 = st->h[1];
h2 = st->h[2];
while (inlen >= POLY1305_BLOCK_SIZE) {
uint64_t t0, t1;
/* h += in[i] */
t0 = U8TO64(in + 0);
t1 = U8TO64(in + 8);
h0 += (( t0 ) & 0xfffffffffff);
h1 += (((t0 >> 44) | (t1 << 20)) & 0xfffffffffff);
h2 += (((t1 >> 24) ) & 0x3ffffffffff) | hibit;
/* h *= r */
d0 = ((uint128_t)h0 * r0) + ((uint128_t)h1 * s2) + ((uint128_t)h2 * s1);
d1 = ((uint128_t)h0 * r1) + ((uint128_t)h1 * r0) + ((uint128_t)h2 * s2);
d2 = ((uint128_t)h0 * r2) + ((uint128_t)h1 * r1) + ((uint128_t)h2 * r0);
/* (partial) h %= p */
c = (uint64_t)(d0 >> 44); h0 = (uint64_t)d0 & 0xfffffffffff;
d1 += c; c = (uint64_t)(d1 >> 44); h1 = (uint64_t)d1 & 0xfffffffffff;
d2 += c; c = (uint64_t)(d2 >> 42); h2 = (uint64_t)d2 & 0x3ffffffffff;
h0 += c * 5; c = (h0 >> 44); h0 = h0 & 0xfffffffffff;
h1 += c;
in += POLY1305_BLOCK_SIZE;
inlen -= POLY1305_BLOCK_SIZE;
}
st->h[0] = h0;
st->h[1] = h1;
st->h[2] = h2;
}
void
poly1305_finish_ext_ref(void *state, const unsigned char *in, size_t remaining, unsigned char mac[16]) {
poly1305_state_ref_t *st = (poly1305_state_ref_t *)state;
uint64_t h0, h1, h2, c;
uint64_t g0, g1, g2;
uint64_t t0, t1;
/* process the remaining block */
if (remaining) {
unsigned char final[POLY1305_BLOCK_SIZE] = {0};
size_t i;
for (i = 0; i < remaining; i++)
final[i] = in[i];
final[remaining] = 1;
st->final = 1;
poly1305_blocks_ref(st, final, POLY1305_BLOCK_SIZE);
}
/* fully carry h */
h0 = st->h[0];
h1 = st->h[1];
h2 = st->h[2];
c = (h1 >> 44); h1 &= 0xfffffffffff;
h2 += c; c = (h2 >> 42); h2 &= 0x3ffffffffff;
h0 += c * 5; c = (h0 >> 44); h0 &= 0xfffffffffff;
h1 += c; c = (h1 >> 44); h1 &= 0xfffffffffff;
h2 += c; c = (h2 >> 42); h2 &= 0x3ffffffffff;
h0 += c * 5; c = (h0 >> 44); h0 &= 0xfffffffffff;
h1 += c;
/* compute h + -p */
g0 = h0 + 5; c = (g0 >> 44); g0 &= 0xfffffffffff;
g1 = h1 + c; c = (g1 >> 44); g1 &= 0xfffffffffff;
g2 = h2 + c - ((uint64_t)1 << 42);
/* select h if h < p, or h + -p if h >= p */
c = (g2 >> 63) - 1;
h0 = (h0 & ~c) | (g0 & c);
h1 = (h1 & ~c) | (g1 & c);
h2 = (h2 & ~c) | (g2 & c);
/* h = (h + pad) */
t0 = st->pad[0];
t1 = st->pad[1];
h0 += (( t0 ) & 0xfffffffffff) ; c = (h0 >> 44); h0 &= 0xfffffffffff;
h1 += (((t0 >> 44) | (t1 << 20)) & 0xfffffffffff) + c; c = (h1 >> 44); h1 &= 0xfffffffffff;
h2 += (((t1 >> 24) ) & 0x3ffffffffff) + c; h2 &= 0x3ffffffffff;
/* mac = h % (2^128) */
h0 = ((h0 ) | (h1 << 44));
h1 = ((h1 >> 20) | (h2 << 24));
U64TO8(&mac[0], h0);
U64TO8(&mac[8], h1);
/* zero out the state */
st->h[0] = 0;
st->h[1] = 0;
st->h[2] = 0;
st->r[0] = 0;
st->r[1] = 0;
st->r[2] = 0;
st->pad[0] = 0;
st->pad[1] = 0;
}
void
poly1305_auth_ref(unsigned char mac[16], const unsigned char *in, size_t inlen, const poly1305_key *key) {
poly1305_state_ref_t st;
size_t blocks;
poly1305_init_ext_ref(&st, key, inlen);
blocks = (inlen & ~(POLY1305_BLOCK_SIZE - 1));
if (blocks) {
poly1305_blocks_ref(&st, in, blocks);
in += blocks;
inlen -= blocks;
}
poly1305_finish_ext_ref(&st, in, inlen, mac);
}
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