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boringssl/boringssl/ba1fa13f7e5fd39dcbc04f7a1255115a4c448c16/./crypto/fipsmodule/mlkem/mlkem.cc.inc
blob: a73d5d95dc70a884d28356e20ddcc5abc74ee086 [file]
// Copyright 2014 The BoringSSL Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include <openssl/base.h>
#include <assert.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/base.h>
#include <openssl/bytestring.h>
#include <openssl/mem.h>
#include <openssl/rand.h>
#include "../../internal.h"
#include "../bcm_interface.h"
#include "../keccak/internal.h"
using namespace bssl;
#if defined(BORINGSSL_FIPS)
DEFINE_STATIC_ONCE(g_mlkem_keygen_self_test_once)
DEFINE_STATIC_ONCE(g_mlkem_encap_self_test_once)
DEFINE_STATIC_ONCE(g_mlkem_decap_self_test_once)
#endif
namespace mlkem {
namespace {
namespace fips {
void ensure_keygen_self_test();
void ensure_encap_self_test();
void ensure_decap_self_test();
} // namespace fips
// See
// https://csrc.nist.gov/pubs/fips/203/final
inline void prf(uint8_t *out, size_t out_len, const uint8_t in[33]) {
BORINGSSL_keccak(out, out_len, in, 33, boringssl_shake256);
}
#if defined(HAVE_KECCAK_X2)
inline void prf_x2(uint8_t *outs[2], size_t out_len,
const uint8_t *ins[2] /* 33 each */) {
BORINGSSL_keccak_short_x2(outs, out_len, ins, 33, boringssl_shake256);
}
#endif
// Section 4.1
void hash_h(uint8_t out[32], const uint8_t *in, size_t len) {
BORINGSSL_keccak(out, 32, in, len, boringssl_sha3_256);
}
void hash_g(uint8_t out[64], const uint8_t *in, size_t len) {
BORINGSSL_keccak(out, 64, in, len, boringssl_sha3_512);
}
// This is called `J` in the spec.
void kdf(uint8_t out[MLKEM_SHARED_SECRET_BYTES],
const uint8_t failure_secret[32], const uint8_t *ciphertext,
size_t ciphertext_len) {
BORINGSSL_keccak_st st;
BORINGSSL_keccak_init(&st, boringssl_shake256);
BORINGSSL_keccak_absorb(&st, failure_secret, 32);
BORINGSSL_keccak_absorb(&st, ciphertext, ciphertext_len);
BORINGSSL_keccak_squeeze(&st, out, MLKEM_SHARED_SECRET_BYTES);
}
// Constants that are common across all sizes.
#define DEGREE 256
const size_t kBarrettMultiplier = 5039;
const unsigned kBarrettShift = 24;
const uint16_t kPrime = 3329;
const int kLog2Prime = 12;
const uint16_t kHalfPrime = (/*kPrime=*/3329 - 1) / 2;
// kInverseDegree is 128^-1 mod 3329; 128 because kPrime does not have a 512th
// root of unity.
const uint16_t kInverseDegree = 3303;
// Rank-specific constants.
#define RANK768 3
const int kDU768 = 10;
const int kDV768 = 4;
#define RANK1024 4
const int kDU1024 = 11;
const int kDV1024 = 5;
constexpr size_t encoded_vector_size(int rank) {
return (kLog2Prime * DEGREE / 8) * static_cast<size_t>(rank);
}
constexpr size_t encoded_public_key_size(int rank) {
return encoded_vector_size(rank) + /*sizeof(rho)=*/32;
}
static_assert(encoded_public_key_size(RANK768) == MLKEM768_PUBLIC_KEY_BYTES);
static_assert(encoded_public_key_size(RANK1024) == MLKEM1024_PUBLIC_KEY_BYTES);
constexpr size_t compressed_vector_size(int rank) {
// `if constexpr` isn't available in C++17.
return (rank == RANK768 ? kDU768 : kDU1024) * static_cast<size_t>(rank) *
DEGREE / 8;
}
constexpr size_t ciphertext_size(int rank) {
return compressed_vector_size(rank) +
(rank == RANK768 ? kDV768 : kDV1024) * DEGREE / 8;
}
static_assert(ciphertext_size(RANK768) == MLKEM768_CIPHERTEXT_BYTES);
static_assert(ciphertext_size(RANK1024) == MLKEM1024_CIPHERTEXT_BYTES);
struct scalar {
// On every function entry and exit, 0 <= c < kPrime.
uint16_t c[DEGREE];
};
template <int RANK>
struct vector {
scalar v[RANK];
};
template <int RANK>
struct matrix {
scalar v[RANK][RANK];
};
// This bit of Python will be referenced in some of the following comments:
//
// p = 3329
//
// def bitreverse(i):
// ret = 0
// for n in range(7):
// bit = i & 1
// ret <<= 1
// ret |= bit
// i >>= 1
// return ret
// kNTTRoots = [pow(17, bitreverse(i), p) for i in range(128)]
const uint16_t kNTTRoots[128] = {
1, 1729, 2580, 3289, 2642, 630, 1897, 848, 1062, 1919, 193, 797,
2786, 3260, 569, 1746, 296, 2447, 1339, 1476, 3046, 56, 2240, 1333,
1426, 2094, 535, 2882, 2393, 2879, 1974, 821, 289, 331, 3253, 1756,
1197, 2304, 2277, 2055, 650, 1977, 2513, 632, 2865, 33, 1320, 1915,
2319, 1435, 807, 452, 1438, 2868, 1534, 2402, 2647, 2617, 1481, 648,
2474, 3110, 1227, 910, 17, 2761, 583, 2649, 1637, 723, 2288, 1100,
1409, 2662, 3281, 233, 756, 2156, 3015, 3050, 1703, 1651, 2789, 1789,
1847, 952, 1461, 2687, 939, 2308, 2437, 2388, 733, 2337, 268, 641,
1584, 2298, 2037, 3220, 375, 2549, 2090, 1645, 1063, 319, 2773, 757,
2099, 561, 2466, 2594, 2804, 1092, 403, 1026, 1143, 2150, 2775, 886,
1722, 1212, 1874, 1029, 2110, 2935, 885, 2154,
};
// kInverseNTTRoots = [pow(17, -bitreverse(i), p) for i in range(128)]
const uint16_t kInverseNTTRoots[128] = {
1, 1600, 40, 749, 2481, 1432, 2699, 687, 1583, 2760, 69, 543,
2532, 3136, 1410, 2267, 2508, 1355, 450, 936, 447, 2794, 1235, 1903,
1996, 1089, 3273, 283, 1853, 1990, 882, 3033, 2419, 2102, 219, 855,
2681, 1848, 712, 682, 927, 1795, 461, 1891, 2877, 2522, 1894, 1010,
1414, 2009, 3296, 464, 2697, 816, 1352, 2679, 1274, 1052, 1025, 2132,
1573, 76, 2998, 3040, 1175, 2444, 394, 1219, 2300, 1455, 2117, 1607,
2443, 554, 1179, 2186, 2303, 2926, 2237, 525, 735, 863, 2768, 1230,
2572, 556, 3010, 2266, 1684, 1239, 780, 2954, 109, 1292, 1031, 1745,
2688, 3061, 992, 2596, 941, 892, 1021, 2390, 642, 1868, 2377, 1482,
1540, 540, 1678, 1626, 279, 314, 1173, 2573, 3096, 48, 667, 1920,
2229, 1041, 2606, 1692, 680, 2746, 568, 3312,
};
// kModRoots = [pow(17, 2*bitreverse(i) + 1, p) for i in range(128)]
const uint16_t kModRoots[128] = {
17, 3312, 2761, 568, 583, 2746, 2649, 680, 1637, 1692, 723, 2606,
2288, 1041, 1100, 2229, 1409, 1920, 2662, 667, 3281, 48, 233, 3096,
756, 2573, 2156, 1173, 3015, 314, 3050, 279, 1703, 1626, 1651, 1678,
2789, 540, 1789, 1540, 1847, 1482, 952, 2377, 1461, 1868, 2687, 642,
939, 2390, 2308, 1021, 2437, 892, 2388, 941, 733, 2596, 2337, 992,
268, 3061, 641, 2688, 1584, 1745, 2298, 1031, 2037, 1292, 3220, 109,
375, 2954, 2549, 780, 2090, 1239, 1645, 1684, 1063, 2266, 319, 3010,
2773, 556, 757, 2572, 2099, 1230, 561, 2768, 2466, 863, 2594, 735,
2804, 525, 1092, 2237, 403, 2926, 1026, 2303, 1143, 2186, 2150, 1179,
2775, 554, 886, 2443, 1722, 1607, 1212, 2117, 1874, 1455, 1029, 2300,
2110, 1219, 2935, 394, 885, 2444, 2154, 1175,
};
// reduce_once reduces 0 <= x < 2*kPrime, mod kPrime.
inline uint16_t reduce_once(uint16_t x) {
declassify_assert(x < 2 * kPrime);
const uint16_t subtracted = x - kPrime;
uint16_t mask = 0u - (subtracted >> 15);
// Although this is a constant-time select, we omit a value barrier here.
// Value barriers impede auto-vectorization (likely because it forces the
// value to transit through a general-purpose register). On AArch64, this is a
// difference of 2x.
//
// We usually add value barriers to selects because Clang turns consecutive
// selects with the same condition into a branch instead of CMOV/CSEL. This
// condition does not occur in ML-KEM, so omitting it seems to be safe so far,
// but see `scalar_centered_binomial_distribution_eta_2_with_prf`.
return (mask & x) | (~mask & subtracted);
}
// constant time reduce x mod kPrime using Barrett reduction. x must be less
// than kPrime + 2×kPrime².
inline uint16_t reduce(uint32_t x) {
declassify_assert(x < kPrime + 2u * kPrime * kPrime);
uint64_t product = (uint64_t)x * kBarrettMultiplier;
uint32_t quotient = (uint32_t)(product >> kBarrettShift);
uint32_t remainder = x - quotient * kPrime;
return reduce_once(remainder);
}
inline void scalar_zero(scalar *out) { OPENSSL_memset(out, 0, sizeof(*out)); }
template <int RANK>
inline void vector_zero(vector<RANK> *out) {
OPENSSL_memset(out->v, 0, sizeof(scalar) * RANK);
}
// In place number theoretic transform of a given scalar.
// Note that MLKEM's kPrime 3329 does not have a 512th root of unity, so this
// transform leaves off the last iteration of the usual FFT code, with the 128
// relevant roots of unity being stored in `kNTTRoots`. This means the output
// should be seen as 128 elements in GF(3329^2), with the coefficients of the
// elements being consecutive entries in `s->c`.
inline void scalar_ntt(scalar *s) {
// Manually unrolled loop to maximize vectorization.
#define ITER(step, offset) \
{ \
int k = 0; \
for (int i = 0; i < step; i++) { \
const uint32_t step_root = kNTTRoots[i + step]; \
for (int j = k; j < k + offset; j++) { \
uint16_t odd = reduce(step_root * s->c[j + offset]); \
uint16_t even = s->c[j]; \
s->c[j] = reduce_once(odd + even); \
s->c[j + offset] = reduce_once(even - odd + kPrime); \
} \
k += 2 * offset; \
} \
}
// for (int step = 1; step < DEGREE / 2; step <<= 1)
ITER(1, 128)
ITER(2, 64)
ITER(4, 32)
ITER(8, 16)
ITER(16, 8)
ITER(32, 4)
ITER(64, 2)
static_assert(DEGREE == 256);
#undef ITER
}
template <int RANK>
inline void vector_ntt(vector<RANK> *a) {
for (int i = 0; i < RANK; i++) {
scalar_ntt(&a->v[i]);
}
}
// In place inverse number theoretic transform of a given scalar, with pairs of
// entries of s->v being interpreted as elements of GF(3329^2). Just as with the
// number theoretic transform, this leaves off the first step of the normal iFFT
// to account for the fact that 3329 does not have a 512th root of unity, using
// the precomputed 128 roots of unity stored in `kInverseNTTRoots`.
void scalar_inverse_ntt(scalar *s) {
// Manually unrolled loop to maximize vectorization.
#define ITER(step, offset) \
{ \
int k = 0; \
for (int i = 0; i < step; i++) { \
uint32_t step_root = kInverseNTTRoots[i + step]; \
for (int j = k; j < k + offset; j++) { \
uint16_t odd = s->c[j + offset]; \
uint16_t even = s->c[j]; \
s->c[j] = reduce_once(odd + even); \
s->c[j + offset] = reduce(step_root * (even - odd + kPrime)); \
} \
k += 2 * offset; \
} \
}
// for (int offset = 2; offset < DEGREE; offset <<= 1)
ITER(64, 2)
ITER(32, 4)
ITER(16, 8)
ITER(8, 16)
ITER(4, 32)
ITER(2, 64)
ITER(1, 128)
static_assert(DEGREE == 256);
#undef ITER
for (int i = 0; i < DEGREE; i++) {
s->c[i] = reduce(s->c[i] * kInverseDegree);
}
}
template <int RANK>
void vector_inverse_ntt(vector<RANK> *a) {
for (int i = 0; i < RANK; i++) {
scalar_inverse_ntt(&a->v[i]);
}
}
inline void scalar_add(scalar *lhs, const scalar *rhs) {
for (int i = 0; i < DEGREE; i++) {
lhs->c[i] = reduce_once(lhs->c[i] + rhs->c[i]);
}
}
inline void scalar_sub(scalar *lhs, const scalar *rhs) {
for (int i = 0; i < DEGREE; i++) {
lhs->c[i] = reduce_once(lhs->c[i] - rhs->c[i] + kPrime);
}
}
// Multiplying two scalars in the number theoretically transformed state. Since
// 3329 does not have a 512th root of unity, this means we have to interpret
// the 2*ith and (2*i+1)th entries of the scalar as elements of GF(3329)[X]/(X^2
// - 17^(2*bitreverse(i)+1)) The value of 17^(2*bitreverse(i)+1) mod 3329 is
// stored in the precomputed `kModRoots` table. Note that our Barrett transform
// only allows us to multiply two reduced numbers together, so we need some
// intermediate reduction steps, even if an uint64_t could hold 3 multiplied
// numbers.
inline void scalar_mult(scalar *out, const scalar *lhs, const scalar *rhs) {
for (int i = 0; i < DEGREE / 2; i++) {
uint32_t real_real = (uint32_t)lhs->c[2 * i] * rhs->c[2 * i];
uint32_t img_img = (uint32_t)lhs->c[2 * i + 1] * rhs->c[2 * i + 1];
uint32_t real_img = (uint32_t)lhs->c[2 * i] * rhs->c[2 * i + 1];
uint32_t img_real = (uint32_t)lhs->c[2 * i + 1] * rhs->c[2 * i];
out->c[2 * i] =
reduce(real_real + (uint32_t)reduce(img_img) * kModRoots[i]);
out->c[2 * i + 1] = reduce(img_real + real_img);
}
}
template <int RANK>
inline void vector_add(vector<RANK> *lhs, const vector<RANK> *rhs) {
for (int i = 0; i < RANK; i++) {
scalar_add(&lhs->v[i], &rhs->v[i]);
}
}
template <int RANK>
inline void matrix_mult(vector<RANK> *out, const matrix<RANK> *m,
const vector<RANK> *a) {
vector_zero(out);
for (int i = 0; i < RANK; i++) {
for (int j = 0; j < RANK; j++) {
scalar product;
scalar_mult(&product, &m->v[i][j], &a->v[j]);
scalar_add(&out->v[i], &product);
}
}
}
template <int RANK>
inline void matrix_mult_transpose(vector<RANK> *out, const matrix<RANK> *m,
const vector<RANK> *a) {
vector_zero(out);
for (int i = 0; i < RANK; i++) {
for (int j = 0; j < RANK; j++) {
scalar product;
scalar_mult(&product, &m->v[j][i], &a->v[j]);
scalar_add(&out->v[i], &product);
}
}
}
template <int RANK>
inline void scalar_inner_product(scalar *out, const vector<RANK> *lhs,
const vector<RANK> *rhs) {
scalar_zero(out);
for (int i = 0; i < RANK; i++) {
scalar product;
scalar_mult(&product, &lhs->v[i], &rhs->v[i]);
scalar_add(out, &product);
}
}
inline void scalar_from_keccak_block_vartime(scalar *out, int *done,
const uint8_t block[168]) {
for (size_t i = 0; i < 168 && *done < DEGREE; i += 3) {
uint16_t d1 = block[i] + 256 * (block[i + 1] % 16);
uint16_t d2 = block[i + 1] / 16 + 16 * block[i + 2];
if (d1 < kPrime) {
out->c[(*done)++] = d1;
}
if (d2 < kPrime && *done < DEGREE) {
out->c[(*done)++] = d2;
}
}
}
// Algorithm 7 from the spec. Rejection samples a Keccak stream to get
// uniformly distributed elements. This is used for matrix expansion and only
// operates on public inputs.
inline void scalar_from_keccak_vartime(scalar *out,
BORINGSSL_keccak_st *keccak_ctx) {
assert(keccak_ctx->squeeze_offset == 0);
assert(keccak_ctx->rate_bytes == 168);
static_assert(168 % 3 == 0, "block and coefficient boundaries do not align");
int done = 0;
while (done < DEGREE) {
uint8_t block[168];
BORINGSSL_keccak_squeeze(keccak_ctx, block, sizeof(block));
scalar_from_keccak_block_vartime(out, &done, block);
}
}
#if defined(HAVE_KECCAK_X2)
inline void scalar_from_keccak_vartime_x2(scalar *out[2],
BORINGSSL_keccak_st keccak_ctx[2]) {
assert(keccak_ctx[0].squeeze_offset == 0);
assert(keccak_ctx[0].rate_bytes == 168);
assert(keccak_ctx[1].squeeze_offset == 0);
assert(keccak_ctx[1].rate_bytes == 168);
static_assert(168 % 3 == 0, "block and coefficient boundaries do not align");
int done[2] = {0, 0};
while (done[0] < DEGREE || done[1] < DEGREE) {
uint8_t block[2][168];
uint8_t *blocks[] = {block[0], block[1]};
BORINGSSL_keccak_squeeze_x2(keccak_ctx, blocks, sizeof(block[0]));
scalar_from_keccak_block_vartime(out[0], &done[0], block[0]);
scalar_from_keccak_block_vartime(out[1], &done[1], block[1]);
}
}
#endif
static void scalar_centered_binomial_distribution_eta_2(
scalar *out, const uint8_t entropy[128]) {
for (int i = 0; i < DEGREE; i += 2) {
uint8_t byte = entropy[i / 2];
uint16_t value = (byte & 1) + ((byte >> 1) & 1);
value -= ((byte >> 2) & 1) + ((byte >> 3) & 1);
// Add `kPrime` if `value` underflowed. See `reduce_once` for a discussion
// on why the value barrier is omitted. While this could have been written
// reduce_once(value + kPrime), this is one extra addition and small range
// of `value` tempts some versions of Clang to emit a branch.
uint16_t mask = 0u - (value >> 15);
out->c[i] = ((value + kPrime) & mask) | (value & ~mask);
byte >>= 4;
value = (byte & 1) + ((byte >> 1) & 1);
value -= ((byte >> 2) & 1) + ((byte >> 3) & 1);
// See above.
mask = 0u - (value >> 15);
out->c[i + 1] = ((value + kPrime) & mask) | (value & ~mask);
}
}
// Algorithm 8 from the spec, with eta fixed to two and the PRF call
// included. Creates binominally distributed elements by sampling 2*`eta` bits,
// and setting the coefficient to the count of the first bits minus the count of
// the second bits, resulting in a centered binomial distribution. Since eta is
// two this gives -2/2 with a probability of 1/16, -1/1 with probability 1/4,
// and 0 with probability 3/8.
void scalar_centered_binomial_distribution_eta_2_with_prf(
scalar *out, const uint8_t input[33]) {
uint8_t entropy[128];
static_assert(sizeof(entropy) == 2 * /*kEta=*/2 * DEGREE / 8);
prf(entropy, sizeof(entropy), input);
scalar_centered_binomial_distribution_eta_2(out, entropy);
}
#if defined(HAVE_KECCAK_X2)
// scalar_centered_binomial_distribution_eta_2_with_prf_x2 computes two blocks
// of scalar_centered_binomial_distribution_eta_2_with_prf.
static void scalar_centered_binomial_distribution_eta_2_with_prf_x2(
scalar out[2], uint8_t input[33]) {
uint8_t entropy[2][128];
static_assert(sizeof(entropy[0]) == 2 * /*kEta=*/2 * DEGREE / 8);
uint8_t input1[33];
OPENSSL_memcpy(input1, input, 33);
++input1[32]; // Counter.
uint8_t *entropies[] = {entropy[0], entropy[1]};
const uint8_t *inputs[2] = {input, input1};
prf_x2(entropies, sizeof(entropy[0]), inputs);
for (int k = 0; k < 2; k++) {
scalar_centered_binomial_distribution_eta_2(&out[k], entropy[k]);
}
}
#endif
// Generates a secret vector by using
// `scalar_centered_binomial_distribution_eta_2_with_prf`, using the given seed
// appending and incrementing `counter` for entry of the vector.
template <int RANK>
void vector_generate_secret_eta_2(vector<RANK> *out, uint8_t *counter,
const uint8_t seed[32]) {
uint8_t input[33];
OPENSSL_memcpy(input, seed, 32);
int i = 0;
#if defined(HAVE_KECCAK_X2)
for (; i + 2 <= RANK; i += 2) {
input[32] = *counter;
*counter += 2;
scalar_centered_binomial_distribution_eta_2_with_prf_x2(&out->v[i], input);
}
#endif
for (; i < RANK; i++) {
input[32] = (*counter)++;
scalar_centered_binomial_distribution_eta_2_with_prf(&out->v[i], input);
}
}
template <int RANK>
void matrix_expand_step(scalar *out, uint8_t input[34], int i) {
input[32] = i / RANK;
input[33] = i % RANK;
BORINGSSL_keccak_st keccak_ctx;
BORINGSSL_keccak_init(&keccak_ctx, boringssl_shake128);
BORINGSSL_keccak_absorb(&keccak_ctx, input, 34);
scalar_from_keccak_vartime(out, &keccak_ctx);
}
#if defined(HAVE_KECCAK_X2)
template <int RANK>
void matrix_expand_step_x2(matrix<RANK> out[2], uint8_t input[34], int i) {
input[32] = i / RANK;
input[33] = i % RANK;
uint8_t input1[34];
OPENSSL_memcpy(input1, input, 32);
input1[32] = (i + 1) / RANK;
input1[33] = (i + 1) % RANK;
BORINGSSL_keccak_st keccak_ctx[2];
BORINGSSL_keccak_init(&keccak_ctx[0], boringssl_shake128);
BORINGSSL_keccak_init(&keccak_ctx[1], boringssl_shake128);
BORINGSSL_keccak_absorb(&keccak_ctx[0], input, 34);
BORINGSSL_keccak_absorb(&keccak_ctx[1], input1, 34);
scalar *outs[] = {&out->v[i / RANK][i % RANK],
&out->v[(i + 1) / RANK][(i + 1) % RANK]};
scalar_from_keccak_vartime_x2(outs, keccak_ctx);
}
#endif
// Expands the matrix of a seed for key generation and for encaps-CPA.
template <int RANK>
void matrix_expand(matrix<RANK> *out, const uint8_t rho[32]) {
uint8_t input[34];
OPENSSL_memcpy(input, rho, 32);
int i = 0;
#if defined(HAVE_KECCAK_X2)
for (; i + 2 <= RANK * RANK; i += 2) {
matrix_expand_step_x2(out, input, i);
}
#endif
for (; i < RANK * RANK; i++) {
matrix_expand_step<RANK>(&out->v[i / RANK][i % RANK], input, i);
}
}
// Encodes a scalar of 256 `BITS`-bit words into 32*`BITS` bytes by splitting
// and joining into bytes using LSB-first bit order (i.e. opposite to standard
// reading order). See below for examples. If an input is >= 1 << `BITS`, the
// result is undefined.
template <int BITS>
void scalar_encode(uint8_t *out, const scalar *s);
// Encodes a scalar of 256 10-bit words into 320 bytes as follows:
// 000000Aaaaaaaaaa 000000Bbbbbbbbbb 000000Cccccccccc 000000Dddddddddd ...
// -> aaaaaaaa bbbbbbAa ccccBbbb ddCccccc Dddddddd ...
template <>
void scalar_encode<10>(uint8_t out[320], const scalar *s) {
for (int i = 0; i < DEGREE; i += 4) {
uint16_t s0 = s->c[i];
uint16_t s1 = s->c[i + 1];
uint16_t s2 = s->c[i + 2];
uint16_t s3 = s->c[i + 3];
declassify_assert((s0 | s1 | s2 | s3) < (1 << 10));
out[0] = (uint8_t)s0;
out[1] = (uint8_t)((s0 >> 8) | (s1 << 2));
out[2] = (uint8_t)((s1 >> 6) | (s2 << 4));
out[3] = (uint8_t)((s2 >> 4) | (s3 << 6));
out[4] = (uint8_t)(s3 >> 2);
out += 5;
}
}
// Encodes a scalar of 256 12-bit words into 384 bytes as follows:
// 0000Aaaaaaaaaaaa 0000Bbbbbbbbbbbb 0000Cccccccccccc 0000Dddddddddddd ...
// -> aaaaaaaa bbbbAaaa Bbbbbbbb cccccccc ddddCccc Dddddddd ....
template <>
void scalar_encode<12>(uint8_t out[384], const scalar *s) {
for (int i = 0; i < DEGREE; i += 2) {
uint16_t s0 = s->c[i];
uint16_t s1 = s->c[i + 1];
declassify_assert((s0 | s1) < (1 << 12));
out[0] = (uint8_t)s0;
out[1] = (uint8_t)((s0 >> 8) | (s1 << 4));
out[2] = (uint8_t)(s1 >> 4);
out += 3;
}
}
// Encodes a scalar of 256 4-bit words into 128 bytes as follows:
// 000000000000Aaaa 00000000000Bbbb 000000000000Cccc 000000000000Dddd ...
// -> BbbbAaaa DdddCccc ...
template <>
void scalar_encode<4>(uint8_t out[128], const scalar *s) {
for (int i = 0; i < DEGREE; i += 2) {
uint16_t s0 = s->c[i];
uint16_t s1 = s->c[i + 1];
declassify_assert((s0 | s1) < (1 << 4));
out[0] = (uint8_t)(s0 | (s1 << 4));
out += 1;
}
}
// Encodes a scalar of 256 11-bit words into 352 bytes as follows:
// 00000Aaaaaaaaaaa 00000Bbbbbbbbbbb 00000Ccccccccccc 00000Ddddddddddd ...
// -> aaaaaaaa bbbbbAaa ccBbbbbb cccccccc dddddddC eeeeDddd fEeeeeee ...
template <>
void scalar_encode<11>(uint8_t out[352], const scalar *s) {
for (int i = 0; i < DEGREE; i += 8) {
uint16_t s0 = s->c[i];
uint16_t s1 = s->c[i + 1];
uint16_t s2 = s->c[i + 2];
uint16_t s3 = s->c[i + 3];
uint16_t s4 = s->c[i + 4];
uint16_t s5 = s->c[i + 5];
uint16_t s6 = s->c[i + 6];
uint16_t s7 = s->c[i + 7];
declassify_assert((s0 | s1 | s2 | s3 | s4 | s5 | s6 | s7) < (1 << 11));
out[0] = (uint8_t)s0;
out[1] = (uint8_t)((s0 >> 8) | (s1 << 3));
out[2] = (uint8_t)((s1 >> 5) | (s2 << 6));
out[3] = (uint8_t)(s2 >> 2);
out[4] = (uint8_t)((s2 >> 10) | (s3 << 1));
out[5] = (uint8_t)((s3 >> 7) | (s4 << 4));
out[6] = (uint8_t)((s4 >> 4) | (s5 << 7));
out[7] = (uint8_t)(s5 >> 1);
out[8] = (uint8_t)((s5 >> 9) | (s6 << 2));
out[9] = (uint8_t)((s6 >> 6) | (s7 << 5));
out[10] = (uint8_t)(s7 >> 3);
out += 11;
}
}
// Encodes a scalar of 256 5-bit words into 160 bytes as follows:
// 00000000000Aaaaa 00000000000Bbbbb 00000000000Ccccc 00000000000Ddddd ...
// -> bbbAaaaa dCccccBb eeeeDddd ggFffffE HhhhhGgg ...
template <>
void scalar_encode<5>(uint8_t out[160], const scalar *s) {
for (int i = 0; i < DEGREE; i += 8) {
uint16_t s0 = s->c[i];
uint16_t s1 = s->c[i + 1];
uint16_t s2 = s->c[i + 2];
uint16_t s3 = s->c[i + 3];
uint16_t s4 = s->c[i + 4];
uint16_t s5 = s->c[i + 5];
uint16_t s6 = s->c[i + 6];
uint16_t s7 = s->c[i + 7];
declassify_assert((s0 | s1 | s2 | s3 | s4 | s5 | s6 | s7) < (1 << 5));
out[0] = (uint8_t)(s0 | (s1 << 5));
out[1] = (uint8_t)((s1 >> 3) | (s2 << 2) | (s3 << 7));
out[2] = (uint8_t)((s3 >> 1) | (s4 << 4));
out[3] = (uint8_t)((s4 >> 4) | (s5 << 1) | (s6 << 6));
out[4] = (uint8_t)((s6 >> 2) | (s7 << 3));
out += 5;
}
}
// Encodes a scalar of 256 1-bit "words" into 32 bytes as follows:
// 0000000000000A 000000000000000B 000000000000000C 000000000000000D ...
// -> HGFEDCBA PONMLKJI XWVUTSRQ ...
// This order is best understood as the natural way of joining into bytes
// assuming LSB-first bit order.
template <>
void scalar_encode<1>(uint8_t out[32], const scalar *s) {
for (int i = 0; i < DEGREE; i += 8) {
uint8_t out_byte = 0;
for (int j = 0; j < 8; j++) {
declassify_assert(s->c[i + j] <= 1);
out_byte |= s->c[i + j] << j;
}
out[i / 8] = out_byte;
}
}
// Encodes an entire vector into 32*`RANK`*`bits` bytes. Note that since 256
// (DEGREE) is divisible by 8, the individual vector entries will always fill a
// whole number of bytes, so we do not need to worry about bit packing here.
template <int bits, int RANK>
void vector_encode(uint8_t *out, const vector<RANK> *a) {
for (int i = 0; i < RANK; i++) {
scalar_encode<bits>(out + i * bits * DEGREE / 8, &a->v[i]);
}
}
// The inverse of `scalar_encode`. Returns 1 iff the encoded scalar is valid,
// i.e. all components are < `kPrime`. Otherwise, returns 0 and the value of
// `out` is undefined.
template <int BITS>
int scalar_decode(scalar *out, const uint8_t *in);
template <>
int scalar_decode<10>(scalar *out, const uint8_t in[320]) {
for (int i = 0; i < DEGREE; i += 4) {
uint16_t s0 = (uint16_t)(in[0] | ((in[1] & 0x03) << 8));
uint16_t s1 = (uint16_t)((in[1] >> 2) | ((in[2] & 0x0f) << 6));
uint16_t s2 = (uint16_t)((in[2] >> 4) | ((in[3] & 0x3f) << 4));
uint16_t s3 = (uint16_t)((in[3] >> 6) | (in[4] << 2));
out->c[i] = s0;
out->c[i + 1] = s1;
out->c[i + 2] = s2;
out->c[i + 3] = s3;
in += 5;
}
return 1;
}
template <>
int scalar_decode<12>(scalar *out, const uint8_t in[384]) {
for (int i = 0; i < DEGREE; i += 2) {
uint16_t s0 = (uint16_t)(in[0] | ((in[1] & 0x0f) << 8));
uint16_t s1 = (uint16_t)((in[1] >> 4) | (in[2] << 4));
if (constant_time_declassify_int((s0 | s1) >= kPrime)) {
if (s0 >= kPrime || s1 >= kPrime) {
return 0;
}
}
out->c[i] = s0;
out->c[i + 1] = s1;
in += 3;
}
return 1;
}
template <>
int scalar_decode<4>(scalar *out, const uint8_t in[128]) {
for (int i = 0; i < DEGREE; i += 2) {
uint16_t s0 = (uint16_t)(in[0] & 0x0f);
uint16_t s1 = (uint16_t)(in[0] >> 4);
// kPrime is 3329, so 4-bit values are always < kPrime.
out->c[i] = s0;
out->c[i + 1] = s1;
in += 1;
}
return 1;
}
// scalar_decode parses `DEGREE * bits` bits from `in` into `DEGREE` values in
// `out`. It returns one on success and zero if any parsed value is >=
// `kPrime`.
template <>
int scalar_decode<11>(scalar *out, const uint8_t in[352]) {
for (int i = 0; i < DEGREE; i += 8) {
uint16_t s0 = (uint16_t)(in[0] | ((in[1] & 0x07) << 8));
uint16_t s1 = (uint16_t)((in[1] >> 3) | ((in[2] & 0x3f) << 5));
uint16_t s2 =
(uint16_t)((in[2] >> 6) | (in[3] << 2) | ((in[4] & 0x01) << 10));
uint16_t s3 = (uint16_t)((in[4] >> 1) | ((in[5] & 0x0f) << 7));
uint16_t s4 = (uint16_t)((in[5] >> 4) | ((in[6] & 0x7f) << 4));
uint16_t s5 =
(uint16_t)((in[6] >> 7) | (in[7] << 1) | ((in[8] & 0x03) << 9));
uint16_t s6 = (uint16_t)((in[8] >> 2) | ((in[9] & 0x1f) << 6));
uint16_t s7 = (uint16_t)((in[9] >> 5) | (in[10] << 3));
out->c[i] = s0;
out->c[i + 1] = s1;
out->c[i + 2] = s2;
out->c[i + 3] = s3;
out->c[i + 4] = s4;
out->c[i + 5] = s5;
out->c[i + 6] = s6;
out->c[i + 7] = s7;
in += 11;
}
return 1;
}
template <>
int scalar_decode<5>(scalar *out, const uint8_t in[160]) {
for (int i = 0; i < DEGREE; i += 8) {
uint16_t s0 = (uint16_t)(in[0] & 0x1f);
uint16_t s1 = (uint16_t)((in[0] >> 5) | ((in[1] & 0x03) << 3));
uint16_t s2 = (uint16_t)((in[1] >> 2) & 0x1f);
uint16_t s3 = (uint16_t)((in[1] >> 7) | ((in[2] & 0x0f) << 1));
uint16_t s4 = (uint16_t)((in[2] >> 4) | ((in[3] & 0x01) << 4));
uint16_t s5 = (uint16_t)((in[3] >> 1) & 0x1f);
uint16_t s6 = (uint16_t)((in[3] >> 6) | ((in[4] & 0x07) << 2));
uint16_t s7 = (uint16_t)(in[4] >> 3);
// kPrime is 3329, so 5-bit values are always < kPrime.
out->c[i] = s0;
out->c[i + 1] = s1;
out->c[i + 2] = s2;
out->c[i + 3] = s3;
out->c[i + 4] = s4;
out->c[i + 5] = s5;
out->c[i + 6] = s6;
out->c[i + 7] = s7;
in += 5;
}
return 1;
}
template <>
int scalar_decode<1>(scalar *out, const uint8_t in[32]) {
for (int i = 0; i < DEGREE; i += 8) {
uint8_t in_byte = in[i / 8];
for (int j = 0; j < 8; j++) {
out->c[i + j] = (in_byte >> j) & 1;
}
}
return 1;
}
// Decodes 32*`RANK`*`bits` bytes from `in` into `out`. It returns one on
// success or zero if any parsed value is >= `kPrime`.
template <int bits, int RANK>
inline int vector_decode(vector<RANK> *out, const uint8_t *in) {
for (int i = 0; i < RANK; i++) {
if (!scalar_decode<bits>(&out->v[i], in + i * bits * DEGREE / 8)) {
return 0;
}
}
return 1;
}
// Compresses (lossily) an input `x` mod 3329 into `bits` many bits by grouping
// numbers close to each other together. The formula used is
// round(2^`bits`/kPrime*x) mod 2^`bits`.
// Uses Barrett reduction to achieve constant time. Since we need both the
// remainder (for rounding) and the quotient (as the result), we cannot use
// `reduce` here, but need to do the Barrett reduction directly.
inline uint16_t compress(uint16_t x, int bits) {
uint32_t shifted = (uint32_t)x << bits;
uint64_t product = (uint64_t)shifted * kBarrettMultiplier;
uint32_t quotient = (uint32_t)(product >> kBarrettShift);
uint32_t remainder = shifted - quotient * kPrime;
// Adjust the quotient to round correctly:
// 0 <= remainder <= kHalfPrime round to 0
// kHalfPrime < remainder <= kPrime + kHalfPrime round to 1
// kPrime + kHalfPrime < remainder < 2 * kPrime round to 2
declassify_assert(remainder < 2u * kPrime);
quotient += 1 & constant_time_lt_w(kHalfPrime, remainder);
quotient += 1 & constant_time_lt_w(kPrime + kHalfPrime, remainder);
return quotient & ((1 << bits) - 1);
}
// Decompresses `x` by using an equi-distant representative. The formula is
// round(kPrime/2^`bits`*x). Note that 2^`bits` being the divisor allows us to
// implement this logic using only bit operations.
inline uint16_t decompress(uint16_t x, int bits) {
uint32_t product = (uint32_t)x * kPrime;
uint32_t power = 1 << bits;
// This is `product` % power, since `power` is a power of 2.
uint32_t remainder = product & (power - 1);
// This is `product` / power, since `power` is a power of 2.
uint32_t lower = product >> bits;
// The rounding logic works since the first half of numbers mod `power` have a
// 0 as first bit, and the second half has a 1 as first bit, since `power` is
// a power of 2. As a 12 bit number, `remainder` is always positive, so we
// will shift in 0s for a right shift.
return lower + (remainder >> (bits - 1));
}
inline void scalar_compress(scalar *s, int bits) {
for (int i = 0; i < DEGREE; i++) {
s->c[i] = compress(s->c[i], bits);
}
}
inline void scalar_decompress(scalar *s, int bits) {
for (int i = 0; i < DEGREE; i++) {
s->c[i] = decompress(s->c[i], bits);
}
}
template <int RANK>
void vector_compress(vector<RANK> *a, int bits) {
for (int i = 0; i < RANK; i++) {
scalar_compress(&a->v[i], bits);
}
}
template <int RANK>
void vector_decompress(vector<RANK> *a, int bits) {
for (int i = 0; i < RANK; i++) {
scalar_decompress(&a->v[i], bits);
}
}
template <int RANK>
struct public_key {
vector<RANK> t;
uint8_t rho[32];
uint8_t public_key_hash[32];
matrix<RANK> m;
};
template <int RANK>
struct private_key {
public_key<RANK> pub;
vector<RANK> s;
uint8_t fo_failure_secret[32];
};
template <int RANK>
inline void decrypt_cpa(uint8_t out[32], const private_key<RANK> *priv,
const uint8_t ciphertext[MLKEM768_CIPHERTEXT_BYTES]) {
constexpr int du = RANK == RANK768 ? kDU768 : kDU1024;
constexpr int dv = RANK == RANK768 ? kDV768 : kDV1024;
vector<RANK> u;
vector_decode<du>(&u, ciphertext);
vector_decompress(&u, du);
vector_ntt(&u);
scalar v;
scalar_decode<dv>(&v, ciphertext + compressed_vector_size(RANK));
scalar_decompress(&v, dv);
scalar mask;
scalar_inner_product(&mask, &priv->s, &u);
scalar_inverse_ntt(&mask);
scalar_sub(&v, &mask);
scalar_compress(&v, 1);
scalar_encode<1>(out, &v);
}
template <int RANK>
inline bcm_status mlkem_marshal_public_key(CBB *out,
const public_key<RANK> *pub) {
uint8_t *vector_output;
if (!CBB_add_space(out, &vector_output, encoded_vector_size(RANK))) {
return bcm_status::failure;
}
vector_encode<kLog2Prime>(vector_output, &pub->t);
if (!CBB_add_bytes(out, pub->rho, sizeof(pub->rho))) {
return bcm_status::failure;
}
return bcm_status::approved;
}
template <int RANK>
inline bool mlkem_public_keys_equal(const public_key<RANK> *a,
const public_key<RANK> *b) {
return OPENSSL_memcmp(a->public_key_hash, b->public_key_hash, 32) == 0;
}
template <int RANK>
void mlkem_generate_key_external_seed_no_self_test(
uint8_t *out_encoded_public_key, private_key<RANK> *priv,
const uint8_t seed[MLKEM_SEED_BYTES]) {
uint8_t augmented_seed[33];
OPENSSL_memcpy(augmented_seed, seed, 32);
augmented_seed[32] = RANK;
uint8_t hashed[64];
hash_g(hashed, augmented_seed, sizeof(augmented_seed));
const uint8_t *const rho = hashed;
const uint8_t *const sigma = hashed + 32;
// rho is public.
CONSTTIME_DECLASSIFY(rho, 32);
OPENSSL_memcpy(priv->pub.rho, hashed, sizeof(priv->pub.rho));
matrix_expand(&priv->pub.m, rho);
uint8_t counter = 0;
vector_generate_secret_eta_2(&priv->s, &counter, sigma);
vector_ntt(&priv->s);
vector<RANK> error;
vector_generate_secret_eta_2(&error, &counter, sigma);
vector_ntt(&error);
matrix_mult_transpose(&priv->pub.t, &priv->pub.m, &priv->s);
vector_add(&priv->pub.t, &error);
// t is part of the public key and thus is public.
CONSTTIME_DECLASSIFY(&priv->pub.t, sizeof(priv->pub.t));
CBB cbb;
CBB_init_fixed(&cbb, out_encoded_public_key, encoded_public_key_size(RANK));
if (!bcm_success(mlkem_marshal_public_key(&cbb, &priv->pub))) {
abort();
}
hash_h(priv->pub.public_key_hash, out_encoded_public_key,
encoded_public_key_size(RANK));
OPENSSL_memcpy(priv->fo_failure_secret, seed + 32, 32);
}
template <int RANK>
void mlkem_generate_key_external_seed(uint8_t *out_encoded_public_key,
private_key<RANK> *priv,
const uint8_t seed[MLKEM_SEED_BYTES]) {
fips::ensure_keygen_self_test();
mlkem_generate_key_external_seed_no_self_test(out_encoded_public_key, priv,
seed);
}
// Encrypts a message with given randomness to
// the ciphertext in `out`. Without applying the Fujisaki-Okamoto transform this
// would not result in a CCA secure scheme, since lattice schemes are vulnerable
// to decryption failure oracles.
template <int RANK>
void encrypt_cpa(uint8_t *out, const mlkem::public_key<RANK> *pub,
const uint8_t message[32], const uint8_t randomness[32]) {
constexpr int du = RANK == RANK768 ? mlkem::kDU768 : mlkem::kDU1024;
constexpr int dv = RANK == RANK768 ? mlkem::kDV768 : mlkem::kDV1024;
uint8_t counter = 0;
mlkem::vector<RANK> secret;
vector_generate_secret_eta_2(&secret, &counter, randomness);
vector_ntt(&secret);
mlkem::vector<RANK> error;
vector_generate_secret_eta_2(&error, &counter, randomness);
uint8_t input[33];
OPENSSL_memcpy(input, randomness, 32);
input[32] = counter;
mlkem::scalar scalar_error;
scalar_centered_binomial_distribution_eta_2_with_prf(&scalar_error, input);
mlkem::vector<RANK> u;
matrix_mult(&u, &pub->m, &secret);
vector_inverse_ntt(&u);
vector_add(&u, &error);
mlkem::scalar v;
scalar_inner_product(&v, &pub->t, &secret);
scalar_inverse_ntt(&v);
scalar_add(&v, &scalar_error);
mlkem::scalar expanded_message;
scalar_decode<1>(&expanded_message, message);
scalar_decompress(&expanded_message, 1);
scalar_add(&v, &expanded_message);
vector_compress(&u, du);
vector_encode<du>(out, &u);
scalar_compress(&v, dv);
scalar_encode<dv>(out + mlkem::compressed_vector_size(RANK), &v);
}
// See section 6.3
template <int RANK>
void mlkem_decap_no_self_test(
uint8_t out_shared_secret[MLKEM_SHARED_SECRET_BYTES],
const uint8_t *ciphertext, const private_key<RANK> *priv) {
uint8_t decrypted[64];
decrypt_cpa(decrypted, priv, ciphertext);
OPENSSL_memcpy(decrypted + 32, priv->pub.public_key_hash,
sizeof(decrypted) - 32);
uint8_t key_and_randomness[64];
hash_g(key_and_randomness, decrypted, sizeof(decrypted));
constexpr size_t ciphertext_len = ciphertext_size(RANK);
uint8_t expected_ciphertext[MLKEM1024_CIPHERTEXT_BYTES];
static_assert(ciphertext_len <= sizeof(expected_ciphertext));
encrypt_cpa(expected_ciphertext, &priv->pub, decrypted,
key_and_randomness + 32);
uint8_t failure_key[32];
kdf(failure_key, priv->fo_failure_secret, ciphertext, ciphertext_len);
uint8_t mask = constant_time_eq_int_8(
CRYPTO_memcmp(ciphertext, expected_ciphertext, ciphertext_len), 0);
for (int i = 0; i < MLKEM_SHARED_SECRET_BYTES; i++) {
out_shared_secret[i] =
constant_time_select_8(mask, key_and_randomness[i], failure_key[i]);
}
}
template <int RANK>
void mlkem_decap(uint8_t out_shared_secret[MLKEM_SHARED_SECRET_BYTES],
const uint8_t *ciphertext, const private_key<RANK> *priv) {
fips::ensure_decap_self_test();
mlkem_decap_no_self_test(out_shared_secret, ciphertext, priv);
}
// mlkem_parse_public_key_with_trailing_data parses `in` into `pub` but leaves
// trailing data in `in` for the caller.
template <int RANK>
int mlkem_parse_public_key_with_trailing_data(public_key<RANK> *pub, CBS *in) {
CBS orig_in = *in;
CBS t_bytes;
if (!CBS_get_bytes(in, &t_bytes, encoded_vector_size(RANK)) ||
!vector_decode<kLog2Prime>(&pub->t, CBS_data(&t_bytes)) ||
!CBS_copy_bytes(in, pub->rho, sizeof(pub->rho))) {
return 0;
}
matrix_expand(&pub->m, pub->rho);
size_t pub_key_len = CBS_len(&orig_in) - CBS_len(in);
assert(pub_key_len == encoded_public_key_size(RANK));
hash_h(pub->public_key_hash, CBS_data(&orig_in), pub_key_len);
return 1;
}
template <int RANK>
int mlkem_parse_public_key(public_key<RANK> *pub, CBS *in) {
if (!mlkem_parse_public_key_with_trailing_data(pub, in) || //
CBS_len(in) != 0) {
return 0;
}
return 1;
}
template <int RANK>
int mlkem_parse_private_key(private_key<RANK> *priv, CBS *in) {
CBS s_bytes, public_key_hash;
if (!CBS_get_bytes(in, &s_bytes, encoded_vector_size(RANK)) ||
!vector_decode<kLog2Prime>(&priv->s, CBS_data(&s_bytes)) ||
!mlkem_parse_public_key_with_trailing_data(&priv->pub, in) ||
// We compute the public key hash ourselves, but check it matched.
!CBS_get_bytes(in, &public_key_hash, sizeof(priv->pub.public_key_hash)) ||
!CBS_mem_equal(&public_key_hash, priv->pub.public_key_hash,
sizeof(priv->pub.public_key_hash)) ||
!CBS_copy_bytes(in, priv->fo_failure_secret,
sizeof(priv->fo_failure_secret)) ||
CBS_len(in) != 0) {
return 0;
}
return 1;
}
template <int RANK>
int mlkem_marshal_private_key(CBB *out, const private_key<RANK> *priv) {
uint8_t *s_output;
if (!CBB_add_space(out, &s_output, encoded_vector_size(RANK))) {
return 0;
}
vector_encode<kLog2Prime>(s_output, &priv->s);
if (!bcm_success(mlkem_marshal_public_key(out, &priv->pub)) ||
!CBB_add_bytes(out, priv->pub.public_key_hash,
sizeof(priv->pub.public_key_hash)) ||
!CBB_add_bytes(out, priv->fo_failure_secret,
sizeof(priv->fo_failure_secret))) {
return 0;
}
return 1;
}
static_assert(sizeof(MLKEM768_public_key) == sizeof(public_key<RANK768>));
static_assert(alignof(MLKEM768_public_key) == alignof(public_key<RANK768>));
const public_key<RANK768> *public_key_768_from_external(
const MLKEM768_public_key *external) {
return reinterpret_cast<const public_key<RANK768> *>(external);
}
public_key<RANK768> *public_key_768_from_external(
MLKEM768_public_key *external) {
return reinterpret_cast<public_key<RANK768> *>(external);
}
const MLKEM768_public_key *public_key_768_to_external(
const public_key<RANK768> *public_key) {
return reinterpret_cast<const MLKEM768_public_key *>(public_key);
}
static_assert(sizeof(MLKEM1024_public_key) == sizeof(public_key<RANK1024>));
static_assert(alignof(MLKEM1024_public_key) == alignof(public_key<RANK1024>));
const public_key<RANK1024> *public_key_1024_from_external(
const MLKEM1024_public_key *external) {
return reinterpret_cast<const public_key<RANK1024> *>(external);
}
public_key<RANK1024> *public_key_1024_from_external(
MLKEM1024_public_key *external) {
return reinterpret_cast<public_key<RANK1024> *>(external);
}
const MLKEM1024_public_key *public_key_1024_to_external(
const public_key<RANK1024> *public_key) {
return reinterpret_cast<const MLKEM1024_public_key *>(public_key);
}
static_assert(sizeof(MLKEM768_private_key) >= sizeof(private_key<RANK768>));
static_assert(alignof(MLKEM768_private_key) >= alignof(private_key<RANK768>));
const private_key<RANK768> *private_key_768_from_external(
const MLKEM768_private_key *external) {
return reinterpret_cast<const private_key<RANK768> *>(external);
}
private_key<RANK768> *private_key_768_from_external(
MLKEM768_private_key *external) {
return reinterpret_cast<private_key<RANK768> *>(external);
}
static_assert(sizeof(MLKEM1024_private_key) >= sizeof(private_key<RANK1024>));
static_assert(alignof(MLKEM1024_private_key) >= alignof(private_key<RANK1024>));
const private_key<RANK1024> *private_key_1024_from_external(
const MLKEM1024_private_key *external) {
return reinterpret_cast<const private_key<RANK1024> *>(external);
}
private_key<RANK1024> *private_key_1024_from_external(
MLKEM1024_private_key *external) {
return reinterpret_cast<private_key<RANK1024> *>(external);
}
// See section 6.2.
template <int RANK>
void mlkem_encap_external_entropy_no_self_test(
uint8_t *out_ciphertext,
uint8_t out_shared_secret[MLKEM_SHARED_SECRET_BYTES],
const mlkem::public_key<RANK> *pub,
const uint8_t entropy[BCM_MLKEM_ENCAP_ENTROPY]) {
uint8_t input[64];
OPENSSL_memcpy(input, entropy, BCM_MLKEM_ENCAP_ENTROPY);
OPENSSL_memcpy(input + BCM_MLKEM_ENCAP_ENTROPY, pub->public_key_hash,
sizeof(input) - BCM_MLKEM_ENCAP_ENTROPY);
uint8_t key_and_randomness[64];
mlkem::hash_g(key_and_randomness, input, sizeof(input));
encrypt_cpa(out_ciphertext, pub, entropy, key_and_randomness + 32);
// The ciphertext is public.
CONSTTIME_DECLASSIFY(out_ciphertext, mlkem::ciphertext_size(RANK));
static_assert(MLKEM_SHARED_SECRET_BYTES == 32);
memcpy(out_shared_secret, key_and_randomness, 32);
}
template <int RANK>
void mlkem_encap_external_entropy(
uint8_t *out_ciphertext,
uint8_t out_shared_secret[MLKEM_SHARED_SECRET_BYTES],
const mlkem::public_key<RANK> *pub,
const uint8_t entropy[BCM_MLKEM_ENCAP_ENTROPY]) {
fips::ensure_encap_self_test();
mlkem_encap_external_entropy_no_self_test(out_ciphertext, out_shared_secret,
pub, entropy);
}
namespace fips {
#include "fips_known_values.inc"
inline int keygen_self_test() {
uint8_t pub_key[MLKEM768_PUBLIC_KEY_BYTES];
private_key<RANK768> priv;
static_assert(sizeof(kTestEntropy) >= MLKEM_SEED_BYTES);
mlkem_generate_key_external_seed_no_self_test(pub_key, &priv, kTestEntropy);
CBB cbb;
constexpr size_t kMarshaledPrivateKeySize = 2400;
uint8_t priv_bytes[kMarshaledPrivateKeySize];
CBB_init_fixed(&cbb, priv_bytes, sizeof(priv_bytes));
if (!mlkem_marshal_private_key(&cbb, &priv) ||
!BORINGSSL_check_test(kExpectedPrivateKeyBytes, priv_bytes,
"ML-KEM keygen private key") ||
!BORINGSSL_check_test(kExpectedPublicKeyBytes, pub_key,
"ML-KEM keygen public key")) {
return 0;
}
return 1;
}
inline int encap_self_test() {
CBS cbs;
CBS_init(&cbs, kExpectedPublicKeyBytes, sizeof(kExpectedPublicKeyBytes));
public_key<RANK768> pub;
if (!mlkem_parse_public_key(&pub, &cbs)) {
return 0;
}
uint8_t ciphertext[MLKEM768_CIPHERTEXT_BYTES];
uint8_t shared_secret[MLKEM_SHARED_SECRET_BYTES];
static_assert(sizeof(kTestEntropy) >= BCM_MLKEM_ENCAP_ENTROPY);
mlkem_encap_external_entropy_no_self_test(ciphertext, shared_secret, &pub,
kTestEntropy);
if (!BORINGSSL_check_test(ciphertext, kExpectedCiphertext,
"ML-KEM encap ciphertext") ||
!BORINGSSL_check_test(kExpectedSharedSecret, shared_secret,
"ML-KEM encap shared secret")) {
return 0;
}
return 1;
}
inline int decap_self_test() {
CBS cbs;
CBS_init(&cbs, kExpectedPrivateKeyBytes, sizeof(kExpectedPrivateKeyBytes));
private_key<RANK768> priv;
if (!mlkem_parse_private_key(&priv, &cbs)) {
return 0;
}
uint8_t shared_secret[MLKEM_SHARED_SECRET_BYTES];
mlkem_decap_no_self_test(shared_secret, kExpectedCiphertext, &priv);
if (!BORINGSSL_check_test(kExpectedSharedSecret, shared_secret,
"ML-KEM decap shared secret")) {
return 0;
}
uint8_t implicit_rejection_shared_secret[MLKEM_SHARED_SECRET_BYTES];
static_assert(sizeof(kExpectedPrivateKeyBytes) >=
sizeof(kExpectedCiphertext));
mlkem_decap_no_self_test(implicit_rejection_shared_secret,
kExpectedPrivateKeyBytes, &priv);
if (!BORINGSSL_check_test(kExpectedImplicitRejectionSharedSecret,
implicit_rejection_shared_secret,
"ML-KEM decap implicit rejection shared secret")) {
return 0;
}
return 1;
}
#if defined(BORINGSSL_FIPS)
void ensure_keygen_self_test() {
CRYPTO_once(g_mlkem_keygen_self_test_once_bss_get(), []() {
if (!keygen_self_test()) {
BORINGSSL_FIPS_abort();
}
});
}
void ensure_encap_self_test() {
CRYPTO_once(g_mlkem_encap_self_test_once_bss_get(), []() {
if (!encap_self_test()) {
BORINGSSL_FIPS_abort();
}
});
}
void ensure_decap_self_test() {
CRYPTO_once(g_mlkem_decap_self_test_once_bss_get(), []() {
if (!decap_self_test()) {
BORINGSSL_FIPS_abort();
}
});
}
#else
void ensure_keygen_self_test() {}
void ensure_encap_self_test() {}
void ensure_decap_self_test() {}
#endif
} // namespace fips
} // namespace
} // namespace mlkem
bcm_status bssl::BCM_mlkem768_check_fips(
const MLKEM768_private_key *private_key) {
const mlkem::private_key<RANK768> *priv =
mlkem::private_key_768_from_external(private_key);
const uint8_t entropy[BCM_MLKEM_ENCAP_ENTROPY] = {1, 2, 3, 4};
uint8_t ciphertext[MLKEM768_CIPHERTEXT_BYTES];
uint8_t shared_secret[MLKEM_SHARED_SECRET_BYTES];
mlkem_encap_external_entropy_no_self_test(ciphertext, shared_secret,
&priv->pub, entropy);
if (boringssl_fips_break_test("MLKEM_PWCT")) {
shared_secret[0] ^= 1;
}
uint8_t shared_secret2[MLKEM_SHARED_SECRET_BYTES];
mlkem::mlkem_decap_no_self_test(shared_secret2, ciphertext, priv);
if (CRYPTO_memcmp(shared_secret, shared_secret2, sizeof(shared_secret)) !=
0) {
return bcm_status::failure;
}
return bcm_status::approved;
}
bcm_status bssl::BCM_mlkem768_generate_key_fips(
uint8_t out_encoded_public_key[MLKEM768_PUBLIC_KEY_BYTES],
uint8_t optional_out_seed[MLKEM_SEED_BYTES],
MLKEM768_private_key *out_private_key) {
if (out_encoded_public_key == nullptr || out_private_key == nullptr) {
return bcm_status::failure;
}
BCM_mlkem768_generate_key(out_encoded_public_key, optional_out_seed,
out_private_key);
return BCM_mlkem768_check_fips(out_private_key);
}
bcm_infallible bssl::BCM_mlkem768_generate_key(
uint8_t out_encoded_public_key[MLKEM768_PUBLIC_KEY_BYTES],
uint8_t optional_out_seed[MLKEM_SEED_BYTES],
MLKEM768_private_key *out_private_key) {
uint8_t seed[MLKEM_SEED_BYTES];
BCM_rand_bytes(seed, sizeof(seed));
CONSTTIME_SECRET(seed, sizeof(seed));
if (optional_out_seed) {
OPENSSL_memcpy(optional_out_seed, seed, sizeof(seed));
}
BCM_mlkem768_generate_key_external_seed(out_encoded_public_key,
out_private_key, seed);
return bcm_infallible::not_approved;
}
bcm_status bssl::BCM_mlkem768_private_key_from_seed(
MLKEM768_private_key *out_private_key, const uint8_t *seed,
size_t seed_len) {
if (seed_len != MLKEM_SEED_BYTES) {
return bcm_status::failure;
}
uint8_t public_key_bytes[MLKEM768_PUBLIC_KEY_BYTES];
BCM_mlkem768_generate_key_external_seed(public_key_bytes, out_private_key,
seed);
return bcm_status::not_approved;
}
bcm_status bssl::BCM_mlkem1024_check_fips(
const MLKEM1024_private_key *private_key) {
const mlkem::private_key<RANK1024> *priv =
mlkem::private_key_1024_from_external(private_key);
const uint8_t entropy[BCM_MLKEM_ENCAP_ENTROPY] = {1, 2, 3, 4};
uint8_t ciphertext[MLKEM1024_CIPHERTEXT_BYTES];
uint8_t shared_secret[MLKEM_SHARED_SECRET_BYTES];
mlkem_encap_external_entropy_no_self_test(ciphertext, shared_secret,
&priv->pub, entropy);
if (boringssl_fips_break_test("MLKEM_PWCT")) {
shared_secret[0] ^= 1;
}
uint8_t shared_secret2[MLKEM_SHARED_SECRET_BYTES];
mlkem::mlkem_decap_no_self_test(shared_secret2, ciphertext, priv);
if (CRYPTO_memcmp(shared_secret, shared_secret2, sizeof(shared_secret)) !=
0) {
return bcm_status::failure;
}
return bcm_status::approved;
}
bcm_status bssl::BCM_mlkem1024_generate_key_fips(
uint8_t out_encoded_public_key[MLKEM1024_PUBLIC_KEY_BYTES],
uint8_t optional_out_seed[MLKEM_SEED_BYTES],
MLKEM1024_private_key *out_private_key) {
if (out_encoded_public_key == nullptr || out_private_key == nullptr) {
return bcm_status::failure;
}
BCM_mlkem1024_generate_key(out_encoded_public_key, optional_out_seed,
out_private_key);
return BCM_mlkem1024_check_fips(out_private_key);
}
bcm_infallible bssl::BCM_mlkem1024_generate_key(
uint8_t out_encoded_public_key[MLKEM1024_PUBLIC_KEY_BYTES],
uint8_t optional_out_seed[MLKEM_SEED_BYTES],
MLKEM1024_private_key *out_private_key) {
uint8_t seed[MLKEM_SEED_BYTES];
BCM_rand_bytes(seed, sizeof(seed));
CONSTTIME_SECRET(seed, sizeof(seed));
if (optional_out_seed) {
OPENSSL_memcpy(optional_out_seed, seed, sizeof(seed));
}
BCM_mlkem1024_generate_key_external_seed(out_encoded_public_key,
out_private_key, seed);
return bcm_infallible::not_approved;
}
bcm_status bssl::BCM_mlkem1024_private_key_from_seed(
MLKEM1024_private_key *out_private_key, const uint8_t *seed,
size_t seed_len) {
if (seed_len != MLKEM_SEED_BYTES) {
return bcm_status::failure;
}
uint8_t public_key_bytes[MLKEM1024_PUBLIC_KEY_BYTES];
BCM_mlkem1024_generate_key_external_seed(public_key_bytes, out_private_key,
seed);
return bcm_status::not_approved;
}
bcm_infallible bssl::BCM_mlkem768_generate_key_external_seed(
uint8_t out_encoded_public_key[MLKEM768_PUBLIC_KEY_BYTES],
MLKEM768_private_key *out_private_key,
const uint8_t seed[MLKEM_SEED_BYTES]) {
mlkem::private_key<RANK768> *priv =
mlkem::private_key_768_from_external(out_private_key);
mlkem_generate_key_external_seed(out_encoded_public_key, priv, seed);
return bcm_infallible::approved;
}
bcm_infallible bssl::BCM_mlkem1024_generate_key_external_seed(
uint8_t out_encoded_public_key[MLKEM1024_PUBLIC_KEY_BYTES],
MLKEM1024_private_key *out_private_key,
const uint8_t seed[MLKEM_SEED_BYTES]) {
mlkem::private_key<RANK1024> *priv =
mlkem::private_key_1024_from_external(out_private_key);
mlkem_generate_key_external_seed(out_encoded_public_key, priv, seed);
return bcm_infallible::approved;
}
bcm_infallible bssl::BCM_mlkem768_public_from_private(
MLKEM768_public_key *out_public_key,
const MLKEM768_private_key *private_key) {
mlkem::public_key<RANK768> *const pub =
mlkem::public_key_768_from_external(out_public_key);
const mlkem::private_key<RANK768> *const priv =
mlkem::private_key_768_from_external(private_key);
*pub = priv->pub;
return bcm_infallible::approved;
}
bcm_infallible bssl::BCM_mlkem1024_public_from_private(
MLKEM1024_public_key *out_public_key,
const MLKEM1024_private_key *private_key) {
mlkem::public_key<RANK1024> *const pub =
mlkem::public_key_1024_from_external(out_public_key);
const mlkem::private_key<RANK1024> *const priv =
mlkem::private_key_1024_from_external(private_key);
*pub = priv->pub;
return bcm_infallible::approved;
}
const MLKEM768_public_key *bssl::BCM_mlkem768_public_of_private(
const MLKEM768_private_key *private_key) {
const mlkem::private_key<RANK768> *const priv =
mlkem::private_key_768_from_external(private_key);
return mlkem::public_key_768_to_external(&priv->pub);
}
const MLKEM1024_public_key *bssl::BCM_mlkem1024_public_of_private(
const MLKEM1024_private_key *private_key) {
const mlkem::private_key<RANK1024> *const priv =
mlkem::private_key_1024_from_external(private_key);
return mlkem::public_key_1024_to_external(&priv->pub);
}
// Calls `MLKEM768_encap_external_entropy` with random bytes from
// `BCM_rand_bytes`
bcm_infallible bssl::BCM_mlkem768_encap(
uint8_t out_ciphertext[MLKEM768_CIPHERTEXT_BYTES],
uint8_t out_shared_secret[MLKEM_SHARED_SECRET_BYTES],
const MLKEM768_public_key *public_key) {
uint8_t entropy[BCM_MLKEM_ENCAP_ENTROPY];
BCM_rand_bytes(entropy, BCM_MLKEM_ENCAP_ENTROPY);
CONSTTIME_SECRET(entropy, BCM_MLKEM_ENCAP_ENTROPY);
BCM_mlkem768_encap_external_entropy(out_ciphertext, out_shared_secret,
public_key, entropy);
return bcm_infallible::approved;
}
bcm_infallible bssl::BCM_mlkem1024_encap(
uint8_t out_ciphertext[MLKEM1024_CIPHERTEXT_BYTES],
uint8_t out_shared_secret[MLKEM_SHARED_SECRET_BYTES],
const MLKEM1024_public_key *public_key) {
uint8_t entropy[BCM_MLKEM_ENCAP_ENTROPY];
BCM_rand_bytes(entropy, BCM_MLKEM_ENCAP_ENTROPY);
CONSTTIME_SECRET(entropy, BCM_MLKEM_ENCAP_ENTROPY);
BCM_mlkem1024_encap_external_entropy(out_ciphertext, out_shared_secret,
public_key, entropy);
return bcm_infallible::approved;
}
bcm_infallible bssl::BCM_mlkem768_encap_external_entropy(
uint8_t out_ciphertext[MLKEM768_CIPHERTEXT_BYTES],
uint8_t out_shared_secret[MLKEM_SHARED_SECRET_BYTES],
const MLKEM768_public_key *public_key,
const uint8_t entropy[BCM_MLKEM_ENCAP_ENTROPY]) {
const mlkem::public_key<RANK768> *pub =
mlkem::public_key_768_from_external(public_key);
mlkem_encap_external_entropy(out_ciphertext, out_shared_secret, pub, entropy);
return bcm_infallible::approved;
}
bcm_infallible bssl::BCM_mlkem1024_encap_external_entropy(
uint8_t out_ciphertext[MLKEM1024_CIPHERTEXT_BYTES],
uint8_t out_shared_secret[MLKEM_SHARED_SECRET_BYTES],
const MLKEM1024_public_key *public_key,
const uint8_t entropy[BCM_MLKEM_ENCAP_ENTROPY]) {
const mlkem::public_key<RANK1024> *pub =
mlkem::public_key_1024_from_external(public_key);
mlkem_encap_external_entropy(out_ciphertext, out_shared_secret, pub, entropy);
return bcm_infallible::approved;
}
bcm_status bssl::BCM_mlkem768_decap(
uint8_t out_shared_secret[MLKEM_SHARED_SECRET_BYTES],
const uint8_t *ciphertext, size_t ciphertext_len,
const MLKEM768_private_key *private_key) {
if (ciphertext_len != MLKEM768_CIPHERTEXT_BYTES) {
BCM_rand_bytes(out_shared_secret, MLKEM_SHARED_SECRET_BYTES);
return bcm_status::failure;
}
const mlkem::private_key<RANK768> *priv =
mlkem::private_key_768_from_external(private_key);
mlkem_decap(out_shared_secret, ciphertext, priv);
return bcm_status::approved;
}
bcm_status bssl::BCM_mlkem1024_decap(
uint8_t out_shared_secret[MLKEM_SHARED_SECRET_BYTES],
const uint8_t *ciphertext, size_t ciphertext_len,
const MLKEM1024_private_key *private_key) {
if (ciphertext_len != MLKEM1024_CIPHERTEXT_BYTES) {
BCM_rand_bytes(out_shared_secret, MLKEM_SHARED_SECRET_BYTES);
return bcm_status::failure;
}
const mlkem::private_key<RANK1024> *priv =
mlkem::private_key_1024_from_external(private_key);
mlkem_decap(out_shared_secret, ciphertext, priv);
return bcm_status::approved;
}
bcm_status bssl::BCM_mlkem768_marshal_public_key(
CBB *out, const MLKEM768_public_key *public_key) {
return mlkem_marshal_public_key(
out, mlkem::public_key_768_from_external(public_key));
}
bcm_status bssl::BCM_mlkem1024_marshal_public_key(
CBB *out, const MLKEM1024_public_key *public_key) {
return mlkem_marshal_public_key(
out, mlkem::public_key_1024_from_external(public_key));
}
int bssl::BCM_mlkem768_public_keys_equal(const MLKEM768_public_key *a,
const MLKEM768_public_key *b) {
const auto *pub_a = mlkem::public_key_768_from_external(a);
const auto *pub_b = mlkem::public_key_768_from_external(b);
if (mlkem_public_keys_equal(pub_a, pub_b)) {
return 1;
}
return 0;
}
int bssl::BCM_mlkem1024_public_keys_equal(const MLKEM1024_public_key *a,
const MLKEM1024_public_key *b) {
const auto *pub_a = mlkem::public_key_1024_from_external(a);
const auto *pub_b = mlkem::public_key_1024_from_external(b);
if (mlkem_public_keys_equal(pub_a, pub_b)) {
return 1;
}
return 0;
}
bcm_status bssl::BCM_mlkem768_parse_public_key(MLKEM768_public_key *public_key,
CBS *in) {
mlkem::public_key<RANK768> *pub =
mlkem::public_key_768_from_external(public_key);
if (!mlkem_parse_public_key(pub, in)) {
return bcm_status::failure;
}
return bcm_status::approved;
}
bcm_status bssl::BCM_mlkem1024_parse_public_key(
MLKEM1024_public_key *public_key, CBS *in) {
mlkem::public_key<RANK1024> *pub =
mlkem::public_key_1024_from_external(public_key);
if (!mlkem_parse_public_key(pub, in)) {
return bcm_status::failure;
}
return bcm_status::approved;
}
bcm_status bssl::BCM_mlkem768_marshal_private_key(
CBB *out, const MLKEM768_private_key *private_key) {
const mlkem::private_key<RANK768> *const priv =
mlkem::private_key_768_from_external(private_key);
if (!mlkem_marshal_private_key(out, priv)) {
return bcm_status::failure;
}
return bcm_status::approved;
}
bcm_status bssl::BCM_mlkem1024_marshal_private_key(
CBB *out, const MLKEM1024_private_key *private_key) {
const mlkem::private_key<RANK1024> *const priv =
mlkem::private_key_1024_from_external(private_key);
if (!mlkem_marshal_private_key(out, priv)) {
return bcm_status::failure;
}
return bcm_status::approved;
}
bcm_status bssl::BCM_mlkem768_parse_private_key(
MLKEM768_private_key *out_private_key, CBS *in) {
mlkem::private_key<RANK768> *const priv =
mlkem::private_key_768_from_external(out_private_key);
if (!mlkem_parse_private_key(priv, in)) {
return bcm_status::failure;
}
return bcm_status::approved;
}
bcm_status bssl::BCM_mlkem1024_parse_private_key(
MLKEM1024_private_key *out_private_key, CBS *in) {
mlkem::private_key<RANK1024> *const priv =
mlkem::private_key_1024_from_external(out_private_key);
if (!mlkem_parse_private_key(priv, in)) {
return bcm_status::failure;
}
return bcm_status::approved;
}
int bssl::boringssl_self_test_mlkem() {
return mlkem::fips::keygen_self_test() && mlkem::fips::encap_self_test() &&
mlkem::fips::decap_self_test();
}