1 /* Copyright (c) 2016, Google Inc.
2 *
3 * Permission to use, copy, modify, and/or distribute this software for any
4 * purpose with or without fee is hereby granted, provided that the above
5 * copyright notice and this permission notice appear in all copies.
6 *
7 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
8 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
9 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
10 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
11 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
12 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
13 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
14
15 #include <openssl/base.h>
16
17 #include <assert.h>
18 #include <string.h>
19
20 #include "internal.h"
21 #include "../../internal.h"
22
23
24 // byte_reverse reverses the order of the bytes in |b->c|.
byte_reverse(uint8_t b[16])25 static void byte_reverse(uint8_t b[16]) {
26 uint64_t hi = CRYPTO_load_u64_le(b);
27 uint64_t lo = CRYPTO_load_u64_le(b + 8);
28 CRYPTO_store_u64_le(b, CRYPTO_bswap8(lo));
29 CRYPTO_store_u64_le(b + 8, CRYPTO_bswap8(hi));
30 }
31
32 // reverse_and_mulX_ghash interprets |b| as a reversed element of the GHASH
33 // field, multiplies that by 'x' and serialises the result back into |b|, but
34 // with GHASH's backwards bit ordering.
reverse_and_mulX_ghash(uint8_t b[16])35 static void reverse_and_mulX_ghash(uint8_t b[16]) {
36 uint64_t hi = CRYPTO_load_u64_le(b);
37 uint64_t lo = CRYPTO_load_u64_le(b + 8);
38 const crypto_word_t carry = constant_time_eq_w(hi & 1, 1);
39 hi >>= 1;
40 hi |= lo << 63;
41 lo >>= 1;
42 lo ^= ((uint64_t) constant_time_select_w(carry, 0xe1, 0)) << 56;
43
44 CRYPTO_store_u64_le(b, CRYPTO_bswap8(lo));
45 CRYPTO_store_u64_le(b + 8, CRYPTO_bswap8(hi));
46 }
47
48 // POLYVAL(H, X_1, ..., X_n) =
49 // ByteReverse(GHASH(mulX_GHASH(ByteReverse(H)), ByteReverse(X_1), ...,
50 // ByteReverse(X_n))).
51 //
52 // See https://www.rfc-editor.org/rfc/rfc8452.html#appendix-A.
53
CRYPTO_POLYVAL_init(struct polyval_ctx * ctx,const uint8_t key[16])54 void CRYPTO_POLYVAL_init(struct polyval_ctx *ctx, const uint8_t key[16]) {
55 alignas(8) uint8_t H[16];
56 OPENSSL_memcpy(H, key, 16);
57 reverse_and_mulX_ghash(H);
58
59 int is_avx;
60 CRYPTO_ghash_init(&ctx->gmult, &ctx->ghash, ctx->Htable, &is_avx, H);
61 OPENSSL_memset(&ctx->S, 0, sizeof(ctx->S));
62 }
63
CRYPTO_POLYVAL_update_blocks(struct polyval_ctx * ctx,const uint8_t * in,size_t in_len)64 void CRYPTO_POLYVAL_update_blocks(struct polyval_ctx *ctx, const uint8_t *in,
65 size_t in_len) {
66 assert((in_len & 15) == 0);
67 alignas(8) uint8_t buf[32 * 16];
68
69 while (in_len > 0) {
70 size_t todo = in_len;
71 if (todo > sizeof(buf)) {
72 todo = sizeof(buf);
73 }
74 OPENSSL_memcpy(buf, in, todo);
75 in += todo;
76 in_len -= todo;
77
78 size_t blocks = todo / 16;
79 for (size_t i = 0; i < blocks; i++) {
80 byte_reverse(buf + 16 * i);
81 }
82
83 ctx->ghash(ctx->S, ctx->Htable, buf, todo);
84 }
85 }
86
CRYPTO_POLYVAL_finish(const struct polyval_ctx * ctx,uint8_t out[16])87 void CRYPTO_POLYVAL_finish(const struct polyval_ctx *ctx, uint8_t out[16]) {
88 OPENSSL_memcpy(out, &ctx->S, 16);
89 byte_reverse(out);
90 }
91