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- /* Copyright (c) 2016, Google Inc.
- *
- * Permission to use, copy, modify, and/or distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
- *
- * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
- * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
- * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
- * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
-
- #include <openssl/base.h>
-
- #if !defined(OPENSSL_SMALL)
-
- #include <assert.h>
- #include <string.h>
-
- #include "internal.h"
- #include "../internal.h"
-
-
- /* byte_reverse reverses the order of the bytes in |b->c|. */
- static void byte_reverse(polyval_block *b) {
- const uint64_t t = CRYPTO_bswap8(b->u[0]);
- b->u[0] = CRYPTO_bswap8(b->u[1]);
- b->u[1] = t;
- }
-
- /* reverse_and_mulX_ghash interprets the bytes |b->c| as a reversed element of
- * the GHASH field, multiplies that by 'x' and serialises the result back into
- * |b|, but with GHASH's backwards bit ordering. */
- static void reverse_and_mulX_ghash(polyval_block *b) {
- uint64_t hi = b->u[0];
- uint64_t lo = b->u[1];
- const unsigned carry = constant_time_eq(hi & 1, 1);
- hi >>= 1;
- hi |= lo << 63;
- lo >>= 1;
- lo ^= ((uint64_t) constant_time_select(carry, 0xe1, 0)) << 56;
-
- b->u[0] = CRYPTO_bswap8(lo);
- b->u[1] = CRYPTO_bswap8(hi);
- }
-
- /* POLYVAL(H, X_1, ..., X_n) =
- * ByteReverse(GHASH(mulX_GHASH(ByteReverse(H)), ByteReverse(X_1), ...,
- * ByteReverse(X_n))).
- *
- * See https://tools.ietf.org/html/draft-irtf-cfrg-gcmsiv-02#appendix-A. */
-
- void CRYPTO_POLYVAL_init(struct polyval_ctx *ctx, const uint8_t key[16]) {
- polyval_block H;
- OPENSSL_memcpy(H.c, key, 16);
- reverse_and_mulX_ghash(&H);
-
- CRYPTO_ghash_init(&ctx->gmult, &ctx->ghash, &ctx->H, ctx->Htable, H.c);
- OPENSSL_memset(&ctx->S, 0, sizeof(ctx->S));
- }
-
- void CRYPTO_POLYVAL_update_blocks(struct polyval_ctx *ctx, const uint8_t *in,
- size_t in_len) {
- assert((in_len & 15) == 0);
- polyval_block reversed[32];
-
- while (in_len > 0) {
- size_t todo = in_len;
- if (todo > sizeof(reversed)) {
- todo = sizeof(reversed);
- }
- OPENSSL_memcpy(reversed, in, todo);
- in += todo;
- in_len -= todo;
-
- size_t blocks = todo / sizeof(polyval_block);
- for (size_t i = 0; i < blocks; i++) {
- byte_reverse(&reversed[i]);
- }
-
- ctx->ghash(ctx->S.u, ctx->Htable, (const uint8_t *) reversed, todo);
- }
- }
-
- void CRYPTO_POLYVAL_finish(const struct polyval_ctx *ctx, uint8_t out[16]) {
- polyval_block S = ctx->S;
- byte_reverse(&S);
- OPENSSL_memcpy(out, &S.c, sizeof(polyval_block));
- }
-
-
- #endif /* !OPENSSL_SMALL */
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