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/*
* PSA FFDH layer on top of Mbed TLS crypto
*/
/*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
*/
#include "common.h"
#if defined(MBEDTLS_PSA_CRYPTO_C)
/* This header is only needed because it defines
* MBEDTLS_DHM_RFC7919_FFDHEXXXX_[P|G]_BIN symbols that are used in
* mbedtls_psa_ffdh_set_prime_generator(). Apart from that, this module
* only uses bignum functions for arithmetic. */
#include <mbedtls/dhm.h>
#include <psa/crypto.h>
#include "psa_crypto_core.h"
#include "psa_crypto_ffdh.h"
#include "psa_crypto_random_impl.h"
#include "mbedtls/platform.h"
#include "mbedtls/error.h"
#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_DH_KEY_PAIR_EXPORT) || \
defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_DH_KEY_PAIR_GENERATE) || \
defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_DH_PUBLIC_KEY) || \
defined(MBEDTLS_PSA_BUILTIN_ALG_FFDH)
static psa_status_t mbedtls_psa_ffdh_set_prime_generator(size_t key_size,
mbedtls_mpi *P,
mbedtls_mpi *G)
{
const unsigned char *dhm_P = NULL;
const unsigned char *dhm_G = NULL;
size_t dhm_size_P = 0;
size_t dhm_size_G = 0;
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
if (P == NULL && G == NULL) {
return PSA_ERROR_INVALID_ARGUMENT;
}
#if defined(MBEDTLS_PSA_BUILTIN_DH_RFC7919_2048)
static const unsigned char dhm_P_2048[] =
MBEDTLS_DHM_RFC7919_FFDHE2048_P_BIN;
static const unsigned char dhm_G_2048[] =
MBEDTLS_DHM_RFC7919_FFDHE2048_G_BIN;
#endif /* MBEDTLS_PSA_BUILTIN_DH_RFC7919_2048 */
#if defined(MBEDTLS_PSA_BUILTIN_DH_RFC7919_3072)
static const unsigned char dhm_P_3072[] =
MBEDTLS_DHM_RFC7919_FFDHE3072_P_BIN;
static const unsigned char dhm_G_3072[] =
MBEDTLS_DHM_RFC7919_FFDHE3072_G_BIN;
#endif /* MBEDTLS_PSA_BUILTIN_DH_RFC7919_3072 */
#if defined(MBEDTLS_PSA_BUILTIN_DH_RFC7919_4096)
static const unsigned char dhm_P_4096[] =
MBEDTLS_DHM_RFC7919_FFDHE4096_P_BIN;
static const unsigned char dhm_G_4096[] =
MBEDTLS_DHM_RFC7919_FFDHE4096_G_BIN;
#endif /* MBEDTLS_PSA_BUILTIN_DH_RFC7919_4096 */
#if defined(MBEDTLS_PSA_BUILTIN_DH_RFC7919_6144)
static const unsigned char dhm_P_6144[] =
MBEDTLS_DHM_RFC7919_FFDHE6144_P_BIN;
static const unsigned char dhm_G_6144[] =
MBEDTLS_DHM_RFC7919_FFDHE6144_G_BIN;
#endif /* MBEDTLS_PSA_BUILTIN_DH_RFC7919_6144 */
#if defined(MBEDTLS_PSA_BUILTIN_DH_RFC7919_8192)
static const unsigned char dhm_P_8192[] =
MBEDTLS_DHM_RFC7919_FFDHE8192_P_BIN;
static const unsigned char dhm_G_8192[] =
MBEDTLS_DHM_RFC7919_FFDHE8192_G_BIN;
#endif /* MBEDTLS_PSA_BUILTIN_DH_RFC7919_8192 */
switch (key_size) {
#if defined(MBEDTLS_PSA_BUILTIN_DH_RFC7919_2048)
case sizeof(dhm_P_2048):
dhm_P = dhm_P_2048;
dhm_G = dhm_G_2048;
dhm_size_P = sizeof(dhm_P_2048);
dhm_size_G = sizeof(dhm_G_2048);
break;
#endif /* MBEDTLS_PSA_BUILTIN_DH_RFC7919_2048 */
#if defined(MBEDTLS_PSA_BUILTIN_DH_RFC7919_3072)
case sizeof(dhm_P_3072):
dhm_P = dhm_P_3072;
dhm_G = dhm_G_3072;
dhm_size_P = sizeof(dhm_P_3072);
dhm_size_G = sizeof(dhm_G_3072);
break;
#endif /* MBEDTLS_PSA_BUILTIN_DH_RFC7919_3072 */
#if defined(MBEDTLS_PSA_BUILTIN_DH_RFC7919_4096)
case sizeof(dhm_P_4096):
dhm_P = dhm_P_4096;
dhm_G = dhm_G_4096;
dhm_size_P = sizeof(dhm_P_4096);
dhm_size_G = sizeof(dhm_G_4096);
break;
#endif /* MBEDTLS_PSA_BUILTIN_DH_RFC7919_4096 */
#if defined(MBEDTLS_PSA_BUILTIN_DH_RFC7919_6144)
case sizeof(dhm_P_6144):
dhm_P = dhm_P_6144;
dhm_G = dhm_G_6144;
dhm_size_P = sizeof(dhm_P_6144);
dhm_size_G = sizeof(dhm_G_6144);
break;
#endif /* MBEDTLS_PSA_BUILTIN_DH_RFC7919_6144 */
#if defined(MBEDTLS_PSA_BUILTIN_DH_RFC7919_8192)
case sizeof(dhm_P_8192):
dhm_P = dhm_P_8192;
dhm_G = dhm_G_8192;
dhm_size_P = sizeof(dhm_P_8192);
dhm_size_G = sizeof(dhm_G_8192);
break;
#endif /* MBEDTLS_PSA_BUILTIN_DH_RFC7919_8192 */
default:
return PSA_ERROR_INVALID_ARGUMENT;
}
if (P != NULL) {
MBEDTLS_MPI_CHK(mbedtls_mpi_read_binary(P, dhm_P,
dhm_size_P));
}
if (G != NULL) {
MBEDTLS_MPI_CHK(mbedtls_mpi_read_binary(G, dhm_G,
dhm_size_G));
}
cleanup:
if (ret != 0) {
return mbedtls_to_psa_error(ret);
}
return PSA_SUCCESS;
}
#endif /* MBEDTLS_PSA_BUILTIN_KEY_TYPE_DH_KEY_PAIR_EXPORT ||
MBEDTLS_PSA_BUILTIN_KEY_TYPE_DH_KEY_PAIR_GENERATE ||
MBEDTLS_PSA_BUILTIN_KEY_TYPE_DH_PUBLIC_KEY ||
MBEDTLS_PSA_BUILTIN_ALG_FFDH */
#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_DH_KEY_PAIR_EXPORT) || \
defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_DH_PUBLIC_KEY)
psa_status_t mbedtls_psa_ffdh_export_public_key(
const psa_key_attributes_t *attributes,
const uint8_t *key_buffer,
size_t key_buffer_size,
uint8_t *data,
size_t data_size,
size_t *data_length)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
mbedtls_mpi GX, G, X, P;
psa_key_type_t type = attributes->type;
if (PSA_KEY_TYPE_IS_PUBLIC_KEY(type)) {
if (key_buffer_size > data_size) {
return PSA_ERROR_BUFFER_TOO_SMALL;
}
memcpy(data, key_buffer, key_buffer_size);
memset(data + key_buffer_size, 0,
data_size - key_buffer_size);
*data_length = key_buffer_size;
return PSA_SUCCESS;
}
mbedtls_mpi_init(&GX); mbedtls_mpi_init(&G);
mbedtls_mpi_init(&X); mbedtls_mpi_init(&P);
size_t key_len = PSA_BITS_TO_BYTES(attributes->bits);
status = mbedtls_psa_ffdh_set_prime_generator(key_len, &P, &G);
if (status != PSA_SUCCESS) {
goto cleanup;
}
MBEDTLS_MPI_CHK(mbedtls_mpi_read_binary(&X, key_buffer,
key_buffer_size));
MBEDTLS_MPI_CHK(mbedtls_mpi_exp_mod(&GX, &G, &X, &P, NULL));
MBEDTLS_MPI_CHK(mbedtls_mpi_write_binary(&GX, data, key_len));
*data_length = key_len;
ret = 0;
cleanup:
mbedtls_mpi_free(&P); mbedtls_mpi_free(&G);
mbedtls_mpi_free(&X); mbedtls_mpi_free(&GX);
if (status == PSA_SUCCESS && ret != 0) {
status = mbedtls_to_psa_error(ret);
}
return status;
}
#endif /* MBEDTLS_PSA_BUILTIN_KEY_TYPE_DH_KEY_PAIR_EXPORT ||
MBEDTLS_PSA_BUILTIN_KEY_TYPE_DH_PUBLIC_KEY */
#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_DH_KEY_PAIR_GENERATE)
psa_status_t mbedtls_psa_ffdh_generate_key(
const psa_key_attributes_t *attributes,
uint8_t *key_buffer, size_t key_buffer_size, size_t *key_buffer_length)
{
mbedtls_mpi X, P;
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
mbedtls_mpi_init(&P); mbedtls_mpi_init(&X);
(void) attributes;
status = mbedtls_psa_ffdh_set_prime_generator(key_buffer_size, &P, NULL);
if (status != PSA_SUCCESS) {
goto cleanup;
}
/* RFC7919: Traditional finite field Diffie-Hellman has each peer choose their
secret exponent from the range [2, P-2].
Select random value in range [3, P-1] and decrease it by 1. */
MBEDTLS_MPI_CHK(mbedtls_mpi_random(&X, 3, &P, mbedtls_psa_get_random,
MBEDTLS_PSA_RANDOM_STATE));
MBEDTLS_MPI_CHK(mbedtls_mpi_sub_int(&X, &X, 1));
MBEDTLS_MPI_CHK(mbedtls_mpi_write_binary(&X, key_buffer, key_buffer_size));
*key_buffer_length = key_buffer_size;
cleanup:
mbedtls_mpi_free(&P); mbedtls_mpi_free(&X);
if (status == PSA_SUCCESS && ret != 0) {
return mbedtls_to_psa_error(ret);
}
return status;
}
#endif /* MBEDTLS_PSA_BUILTIN_KEY_TYPE_DH_KEY_PAIR_GENERATE */
#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_DH_KEY_PAIR_IMPORT)
psa_status_t mbedtls_psa_ffdh_import_key(
const psa_key_attributes_t *attributes,
const uint8_t *data, size_t data_length,
uint8_t *key_buffer, size_t key_buffer_size,
size_t *key_buffer_length, size_t *bits)
{
(void) attributes;
if (key_buffer_size < data_length) {
return PSA_ERROR_BUFFER_TOO_SMALL;
}
memcpy(key_buffer, data, data_length);
*key_buffer_length = data_length;
*bits = PSA_BYTES_TO_BITS(data_length);
return PSA_SUCCESS;
}
#endif /* MBEDTLS_PSA_BUILTIN_KEY_TYPE_DH_KEY_PAIR_IMPORT */
#if defined(MBEDTLS_PSA_BUILTIN_ALG_FFDH)
psa_status_t mbedtls_psa_ffdh_key_agreement(
const psa_key_attributes_t *attributes,
const uint8_t *peer_key,
size_t peer_key_length,
const uint8_t *key_buffer,
size_t key_buffer_size,
uint8_t *shared_secret,
size_t shared_secret_size,
size_t *shared_secret_length)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
mbedtls_mpi P, G, X, GY, K;
const size_t calculated_shared_secret_size = peer_key_length;
if (peer_key_length != key_buffer_size ||
calculated_shared_secret_size > shared_secret_size) {
return PSA_ERROR_INVALID_ARGUMENT;
}
if (!PSA_KEY_TYPE_IS_DH_KEY_PAIR(psa_get_key_type(attributes))) {
return PSA_ERROR_INVALID_ARGUMENT;
}
mbedtls_mpi_init(&P); mbedtls_mpi_init(&G);
mbedtls_mpi_init(&X); mbedtls_mpi_init(&GY);
mbedtls_mpi_init(&K);
status = mbedtls_psa_ffdh_set_prime_generator(
PSA_BITS_TO_BYTES(attributes->bits), &P, &G);
if (status != PSA_SUCCESS) {
goto cleanup;
}
MBEDTLS_MPI_CHK(mbedtls_mpi_read_binary(&X, key_buffer,
key_buffer_size));
MBEDTLS_MPI_CHK(mbedtls_mpi_read_binary(&GY, peer_key,
peer_key_length));
/* Calculate shared secret public key: K = G^(XY) mod P = GY^X mod P */
MBEDTLS_MPI_CHK(mbedtls_mpi_exp_mod(&K, &GY, &X, &P, NULL));
MBEDTLS_MPI_CHK(mbedtls_mpi_write_binary(&K, shared_secret,
calculated_shared_secret_size));
*shared_secret_length = calculated_shared_secret_size;
ret = 0;
cleanup:
mbedtls_mpi_free(&P); mbedtls_mpi_free(&G);
mbedtls_mpi_free(&X); mbedtls_mpi_free(&GY);
mbedtls_mpi_free(&K);
if (status == PSA_SUCCESS && ret != 0) {
status = mbedtls_to_psa_error(ret);
}
return status;
}
#endif /* MBEDTLS_PSA_BUILTIN_ALG_FFDH */
#endif /* MBEDTLS_PSA_CRYPTO_C */
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