/* 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_grpc/base.h> #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 crypto_word_t carry = constant_time_eq_w(hi & 1, 1); hi >>= 1; hi |= lo << 63; lo >>= 1; lo ^= ((uint64_t) constant_time_select_w(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); int is_avx; CRYPTO_ghash_init(&ctx->gmult, &ctx->ghash, &ctx->H, ctx->Htable, &is_avx, 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)); }