301 lines
9.5 KiB
C
301 lines
9.5 KiB
C
/*
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* PSA FFDH layer on top of Mbed TLS crypto
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*/
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/*
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* Copyright The Mbed TLS Contributors
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "common.h"
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#if defined(MBEDTLS_PSA_CRYPTO_C)
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#include <psa/crypto.h>
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#include "psa_crypto_core.h"
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#include "psa_crypto_ffdh.h"
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#include "psa_crypto_random_impl.h"
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#include "mbedtls/platform.h"
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#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_DH_KEY_PAIR_LEGACY) || \
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defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_DH_PUBLIC_KEY) || \
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defined(MBEDTLS_PSA_BUILTIN_ALG_FFDH)
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static psa_status_t mbedtls_psa_ffdh_set_prime_generator(size_t key_size,
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mbedtls_mpi *P,
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mbedtls_mpi *G)
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{
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const unsigned char *dhm_P = NULL;
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const unsigned char *dhm_G = NULL;
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size_t dhm_size_P = 0;
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size_t dhm_size_G = 0;
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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if (P == NULL && G == NULL) {
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return PSA_ERROR_INVALID_ARGUMENT;
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}
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static const unsigned char dhm_P_2048[] =
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MBEDTLS_DHM_RFC7919_FFDHE2048_P_BIN;
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static const unsigned char dhm_P_3072[] =
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MBEDTLS_DHM_RFC7919_FFDHE3072_P_BIN;
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static const unsigned char dhm_P_4096[] =
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MBEDTLS_DHM_RFC7919_FFDHE4096_P_BIN;
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static const unsigned char dhm_P_6144[] =
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MBEDTLS_DHM_RFC7919_FFDHE6144_P_BIN;
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static const unsigned char dhm_P_8192[] =
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MBEDTLS_DHM_RFC7919_FFDHE8192_P_BIN;
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static const unsigned char dhm_G_2048[] =
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MBEDTLS_DHM_RFC7919_FFDHE2048_G_BIN;
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static const unsigned char dhm_G_3072[] =
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MBEDTLS_DHM_RFC7919_FFDHE3072_G_BIN;
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static const unsigned char dhm_G_4096[] =
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MBEDTLS_DHM_RFC7919_FFDHE4096_G_BIN;
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static const unsigned char dhm_G_6144[] =
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MBEDTLS_DHM_RFC7919_FFDHE6144_G_BIN;
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static const unsigned char dhm_G_8192[] =
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MBEDTLS_DHM_RFC7919_FFDHE8192_G_BIN;
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switch (key_size) {
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case sizeof(dhm_P_2048):
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dhm_P = dhm_P_2048;
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dhm_G = dhm_G_2048;
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dhm_size_P = sizeof(dhm_P_2048);
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dhm_size_G = sizeof(dhm_G_2048);
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break;
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case sizeof(dhm_P_3072):
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dhm_P = dhm_P_3072;
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dhm_G = dhm_G_3072;
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dhm_size_P = sizeof(dhm_P_3072);
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dhm_size_G = sizeof(dhm_G_3072);
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break;
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case sizeof(dhm_P_4096):
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dhm_P = dhm_P_4096;
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dhm_G = dhm_G_4096;
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dhm_size_P = sizeof(dhm_P_4096);
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dhm_size_G = sizeof(dhm_G_4096);
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break;
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case sizeof(dhm_P_6144):
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dhm_P = dhm_P_6144;
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dhm_G = dhm_G_6144;
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dhm_size_P = sizeof(dhm_P_6144);
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dhm_size_G = sizeof(dhm_G_6144);
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break;
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case sizeof(dhm_P_8192):
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dhm_P = dhm_P_8192;
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dhm_G = dhm_G_8192;
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dhm_size_P = sizeof(dhm_P_8192);
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dhm_size_G = sizeof(dhm_G_8192);
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break;
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default:
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return PSA_ERROR_INVALID_ARGUMENT;
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}
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if (P != NULL) {
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MBEDTLS_MPI_CHK(mbedtls_mpi_read_binary(P, dhm_P,
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dhm_size_P));
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}
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if (G != NULL) {
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MBEDTLS_MPI_CHK(mbedtls_mpi_read_binary(G, dhm_G,
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dhm_size_G));
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}
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cleanup:
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if (ret != 0) {
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return mbedtls_to_psa_error(ret);
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}
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return PSA_SUCCESS;
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}
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#endif /* MBEDTLS_PSA_BUILTIN_KEY_TYPE_DH_KEY_PAIR_LEGACY ||
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MBEDTLS_PSA_BUILTIN_KEY_TYPE_DH_PUBLIC_KEY ||
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MBEDTLS_PSA_BUILTIN_ALG_FFDH */
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#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_DH_KEY_PAIR_LEGACY) || \
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defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_DH_PUBLIC_KEY)
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psa_status_t mbedtls_psa_ffdh_export_public_key(
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const psa_key_attributes_t *attributes,
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const uint8_t *key_buffer,
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size_t key_buffer_size,
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uint8_t *data,
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size_t data_size,
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size_t *data_length)
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{
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
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mbedtls_mpi GX, G, X, P;
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psa_key_type_t type = attributes->core.type;
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if (PSA_KEY_TYPE_IS_PUBLIC_KEY(type)) {
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if (key_buffer_size > data_size) {
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return PSA_ERROR_BUFFER_TOO_SMALL;
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}
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memcpy(data, key_buffer, key_buffer_size);
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memset(data + key_buffer_size, 0,
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data_size - key_buffer_size);
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*data_length = key_buffer_size;
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return PSA_SUCCESS;
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}
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mbedtls_mpi_init(&GX); mbedtls_mpi_init(&G);
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mbedtls_mpi_init(&X); mbedtls_mpi_init(&P);
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size_t key_len = PSA_BITS_TO_BYTES(attributes->core.bits);
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status = mbedtls_psa_ffdh_set_prime_generator(key_len, &P, &G);
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if (status != PSA_SUCCESS) {
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goto cleanup;
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}
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MBEDTLS_MPI_CHK(mbedtls_mpi_read_binary(&X, key_buffer,
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key_buffer_size));
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MBEDTLS_MPI_CHK(mbedtls_mpi_exp_mod(&GX, &G, &X, &P, NULL));
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MBEDTLS_MPI_CHK(mbedtls_mpi_write_binary(&GX, data, key_len));
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*data_length = key_len;
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ret = 0;
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cleanup:
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mbedtls_mpi_free(&P); mbedtls_mpi_free(&G);
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mbedtls_mpi_free(&X); mbedtls_mpi_free(&GX);
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if (status == PSA_SUCCESS && ret != 0) {
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status = mbedtls_to_psa_error(ret);
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}
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return status;
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}
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psa_status_t mbedtls_psa_ffdh_generate_key(
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const psa_key_attributes_t *attributes,
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uint8_t *key_buffer, size_t key_buffer_size, size_t *key_buffer_length)
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{
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mbedtls_mpi X, P;
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
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mbedtls_mpi_init(&P); mbedtls_mpi_init(&X);
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(void) attributes;
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status = mbedtls_psa_ffdh_set_prime_generator(key_buffer_size, &P, NULL);
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if (status != PSA_SUCCESS) {
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goto cleanup;
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}
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/* RFC7919: Traditional finite field Diffie-Hellman has each peer choose their
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secret exponent from the range [2, P-2].
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Select random value in range [3, P-1] and decrease it by 1. */
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MBEDTLS_MPI_CHK(mbedtls_mpi_random(&X, 3, &P, mbedtls_psa_get_random,
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MBEDTLS_PSA_RANDOM_STATE));
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MBEDTLS_MPI_CHK(mbedtls_mpi_sub_int(&X, &X, 1));
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MBEDTLS_MPI_CHK(mbedtls_mpi_write_binary(&X, key_buffer, key_buffer_size));
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*key_buffer_length = key_buffer_size;
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cleanup:
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mbedtls_mpi_free(&P); mbedtls_mpi_free(&X);
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if (status == PSA_SUCCESS && ret != 0) {
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return mbedtls_to_psa_error(ret);
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}
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return status;
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}
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psa_status_t mbedtls_psa_ffdh_import_key(
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const psa_key_attributes_t *attributes,
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const uint8_t *data, size_t data_length,
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uint8_t *key_buffer, size_t key_buffer_size,
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size_t *key_buffer_length, size_t *bits)
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{
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(void) attributes;
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if (key_buffer_size < data_length) {
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return PSA_ERROR_BUFFER_TOO_SMALL;
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}
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memcpy(key_buffer, data, data_length);
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*key_buffer_length = data_length;
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*bits = PSA_BYTES_TO_BITS(data_length);
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return PSA_SUCCESS;
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}
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#endif /* MBEDTLS_PSA_BUILTIN_KEY_TYPE_DH_KEY_PAIR_LEGACY ||
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MBEDTLS_PSA_BUILTIN_KEY_TYPE_DH_PUBLIC_KEY */
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#if defined(MBEDTLS_PSA_BUILTIN_ALG_FFDH)
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psa_status_t mbedtls_psa_ffdh_key_agreement(
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const psa_key_attributes_t *attributes,
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const uint8_t *peer_key,
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size_t peer_key_length,
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const uint8_t *key_buffer,
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size_t key_buffer_size,
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uint8_t *shared_secret,
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size_t shared_secret_size,
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size_t *shared_secret_length)
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{
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
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mbedtls_mpi P, G, X, GY, K;
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const size_t calculated_shared_secret_size = peer_key_length;
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if (peer_key_length != key_buffer_size ||
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calculated_shared_secret_size > shared_secret_size) {
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return PSA_ERROR_INVALID_ARGUMENT;
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}
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if (!PSA_KEY_TYPE_IS_DH_KEY_PAIR(psa_get_key_type(attributes))) {
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return PSA_ERROR_INVALID_ARGUMENT;
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}
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mbedtls_mpi_init(&P); mbedtls_mpi_init(&G);
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mbedtls_mpi_init(&X); mbedtls_mpi_init(&GY);
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mbedtls_mpi_init(&K);
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status = mbedtls_psa_ffdh_set_prime_generator(
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PSA_BITS_TO_BYTES(attributes->core.bits), &P, &G);
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if (status != PSA_SUCCESS) {
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goto cleanup;
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}
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MBEDTLS_MPI_CHK(mbedtls_mpi_read_binary(&X, key_buffer,
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key_buffer_size));
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MBEDTLS_MPI_CHK(mbedtls_mpi_read_binary(&GY, peer_key,
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peer_key_length));
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/* Calculate shared secret public key: K = G^(XY) mod P = GY^X mod P */
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MBEDTLS_MPI_CHK(mbedtls_mpi_exp_mod(&K, &GY, &X, &P, NULL));
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MBEDTLS_MPI_CHK(mbedtls_mpi_write_binary(&K, shared_secret,
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calculated_shared_secret_size));
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*shared_secret_length = calculated_shared_secret_size;
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ret = 0;
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cleanup:
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mbedtls_mpi_free(&P); mbedtls_mpi_free(&G);
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mbedtls_mpi_free(&X); mbedtls_mpi_free(&GY);
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mbedtls_mpi_free(&K);
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if (status == PSA_SUCCESS && ret != 0) {
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status = mbedtls_to_psa_error(ret);
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}
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return status;
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}
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#endif /* MBEDTLS_PSA_BUILTIN_ALG_FFDH */
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#endif /* MBEDTLS_PSA_CRYPTO_C */
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