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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"
- #include "poly1305_internal.h"
-
- #define POLY1305_BLOCK_SIZE 16
-
- 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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