1/* Copyright 2016 The BoringSSL Authors 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|. 25static 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. 35static 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 54void 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 CRYPTO_ghash_init(&ctx->gmult, &ctx->ghash, ctx->Htable, H); 60 OPENSSL_memset(&ctx->S, 0, sizeof(ctx->S)); 61} 62 63void CRYPTO_POLYVAL_update_blocks(struct polyval_ctx *ctx, const uint8_t *in, 64 size_t in_len) { 65 assert((in_len & 15) == 0); 66 alignas(8) uint8_t buf[32 * 16]; 67 68 while (in_len > 0) { 69 size_t todo = in_len; 70 if (todo > sizeof(buf)) { 71 todo = sizeof(buf); 72 } 73 OPENSSL_memcpy(buf, in, todo); 74 in += todo; 75 in_len -= todo; 76 77 size_t blocks = todo / 16; 78 for (size_t i = 0; i < blocks; i++) { 79 byte_reverse(buf + 16 * i); 80 } 81 82 ctx->ghash(ctx->S, ctx->Htable, buf, todo); 83 } 84} 85 86void CRYPTO_POLYVAL_finish(const struct polyval_ctx *ctx, uint8_t out[16]) { 87 OPENSSL_memcpy(out, &ctx->S, 16); 88 byte_reverse(out); 89} 90