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/* Copyright (c) 2023, 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>
#include <assert.h>
#include <stdlib.h>
#include "../internal.h"
#include "./internal.h"
// keccak_f implements the Keccak-1600 permutation as described at
// https://keccak.team/keccak_specs_summary.html. Each lane is represented as a
// 64-bit value and the 5×5 lanes are stored as an array in row-major order.
static void keccak_f(uint64_t state[25]) {
static const int kNumRounds = 24;
for (int round = 0; round < kNumRounds; round++) {
// θ step
uint64_t c[5];
for (int x = 0; x < 5; x++) {
c[x] = state[x] ^ state[x + 5] ^ state[x + 10] ^ state[x + 15] ^
state[x + 20];
}
for (int x = 0; x < 5; x++) {
const uint64_t d = c[(x + 4) % 5] ^ CRYPTO_rotl_u64(c[(x + 1) % 5], 1);
for (int y = 0; y < 5; y++) {
state[y * 5 + x] ^= d;
}
}
// ρ and π steps.
//
// These steps involve a mapping of the state matrix. Each input point,
// (x,y), is rotated and written to the point (y, 2x + 3y). In the Keccak
// pseudo-code a separate array is used because an in-place operation would
// overwrite some values that are subsequently needed. However, the mapping
// forms a trail through 24 of the 25 values so we can do it in place with
// only a single temporary variable.
//
// Start with (1, 0). The value here will be mapped and end up at (0, 2).
// That value will end up at (2, 1), then (1, 2), and so on. After 24
// steps, 24 of the 25 values have been hit (as this mapping is injective)
// and the sequence will repeat. All that remains is to handle the element
// at (0, 0), but the rotation for that element is zero, and it goes to (0,
// 0), so we can ignore it.
static const uint8_t kIndexes[24] = {10, 7, 11, 17, 18, 3, 5, 16,
8, 21, 24, 4, 15, 23, 19, 13,
12, 2, 20, 14, 22, 9, 6, 1};
static const uint8_t kRotations[24] = {1, 3, 6, 10, 15, 21, 28, 36,
45, 55, 2, 14, 27, 41, 56, 8,
25, 43, 62, 18, 39, 61, 20, 44};
uint64_t prev_value = state[1];
for (int i = 0; i < 24; i++) {
const uint64_t value = CRYPTO_rotl_u64(prev_value, kRotations[i]);
const size_t index = kIndexes[i];
prev_value = state[index];
state[index] = value;
}
// χ step
for (int y = 0; y < 5; y++) {
const int row_index = 5 * y;
const uint64_t orig_x0 = state[row_index];
const uint64_t orig_x1 = state[row_index + 1];
state[row_index] ^= ~orig_x1 & state[row_index + 2];
state[row_index + 1] ^= ~state[row_index + 2] & state[row_index + 3];
state[row_index + 2] ^= ~state[row_index + 3] & state[row_index + 4];
state[row_index + 3] ^= ~state[row_index + 4] & orig_x0;
state[row_index + 4] ^= ~orig_x0 & orig_x1;
}
// ι step
//
// From https://keccak.team/files/Keccak-reference-3.0.pdf, section
// 1.2, the round constants are based on the output of a LFSR. Thus, as
// suggested in the appendix of of
// https://keccak.team/keccak_specs_summary.html, the values are
// simply encoded here.
static const uint64_t kRoundConstants[24] = {
0x0000000000000001, 0x0000000000008082, 0x800000000000808a,
0x8000000080008000, 0x000000000000808b, 0x0000000080000001,
0x8000000080008081, 0x8000000000008009, 0x000000000000008a,
0x0000000000000088, 0x0000000080008009, 0x000000008000000a,
0x000000008000808b, 0x800000000000008b, 0x8000000000008089,
0x8000000000008003, 0x8000000000008002, 0x8000000000000080,
0x000000000000800a, 0x800000008000000a, 0x8000000080008081,
0x8000000000008080, 0x0000000080000001, 0x8000000080008008,
};
state[0] ^= kRoundConstants[round];
}
}
static void keccak_init(struct BORINGSSL_keccak_st *ctx,
size_t *out_required_out_len, const uint8_t *in,
size_t in_len, enum boringssl_keccak_config_t config) {
size_t capacity_bytes;
uint8_t terminator;
switch (config) {
case boringssl_sha3_256:
capacity_bytes = 512 / 8;
*out_required_out_len = 32;
terminator = 0x06;
break;
case boringssl_sha3_512:
capacity_bytes = 1024 / 8;
*out_required_out_len = 64;
terminator = 0x06;
break;
case boringssl_shake128:
capacity_bytes = 256 / 8;
*out_required_out_len = 0;
terminator = 0x1f;
break;
case boringssl_shake256:
capacity_bytes = 512 / 8;
*out_required_out_len = 0;
terminator = 0x1f;
break;
default:
abort();
}
OPENSSL_memset(ctx, 0, sizeof(*ctx));
ctx->rate_bytes = 200 - capacity_bytes;
assert(ctx->rate_bytes % 8 == 0);
const size_t rate_words = ctx->rate_bytes / 8;
while (in_len >= ctx->rate_bytes) {
for (size_t i = 0; i < rate_words; i++) {
ctx->state[i] ^= CRYPTO_load_u64_le(in + 8 * i);
}
keccak_f(ctx->state);
in += ctx->rate_bytes;
in_len -= ctx->rate_bytes;
}
// XOR the final block. Accessing |ctx->state| as a |uint8_t*| is allowed by
// strict aliasing because we require |uint8_t| to be a character type.
uint8_t *state_bytes = (uint8_t *)ctx->state;
assert(in_len < ctx->rate_bytes);
for (size_t i = 0; i < in_len; i++) {
state_bytes[i] ^= in[i];
}
state_bytes[in_len] ^= terminator;
state_bytes[ctx->rate_bytes - 1] ^= 0x80;
keccak_f(ctx->state);
}
void BORINGSSL_keccak(uint8_t *out, size_t out_len, const uint8_t *in,
size_t in_len, enum boringssl_keccak_config_t config) {
struct BORINGSSL_keccak_st ctx;
size_t required_out_len;
keccak_init(&ctx, &required_out_len, in, in_len, config);
if (required_out_len != 0 && out_len != required_out_len) {
abort();
}
BORINGSSL_keccak_squeeze(&ctx, out, out_len);
}
void BORINGSSL_keccak_init(struct BORINGSSL_keccak_st *ctx, const uint8_t *in,
size_t in_len,
enum boringssl_keccak_config_t config) {
size_t required_out_len;
keccak_init(ctx, &required_out_len, in, in_len, config);
if (required_out_len != 0) {
abort();
}
}
void BORINGSSL_keccak_squeeze(struct BORINGSSL_keccak_st *ctx, uint8_t *out,
size_t out_len) {
// Accessing |ctx->state| as a |uint8_t*| is allowed by strict aliasing
// because we require |uint8_t| to be a character type.
const uint8_t *state_bytes = (const uint8_t *)ctx->state;
while (out_len) {
size_t remaining = ctx->rate_bytes - ctx->offset;
size_t todo = out_len;
if (todo > remaining) {
todo = remaining;
}
OPENSSL_memcpy(out, &state_bytes[ctx->offset], todo);
out += todo;
out_len -= todo;
ctx->offset += todo;
if (ctx->offset == ctx->rate_bytes) {
keccak_f(ctx->state);
ctx->offset = 0;
}
}
}
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