725 lines
		
	
	
		
			20 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
		
		
			
		
	
	
			725 lines
		
	
	
		
			20 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
|  | /*
 | ||
|  |  *  Diffie-Hellman-Merkle key exchange | ||
|  |  * | ||
|  |  *  Copyright The Mbed TLS Contributors | ||
|  |  *  SPDX-License-Identifier: Apache-2.0 | ||
|  |  * | ||
|  |  *  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 | ||
|  |  * | ||
|  |  *  http://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. | ||
|  |  */ | ||
|  | /*
 | ||
|  |  *  The following sources were referenced in the design of this implementation | ||
|  |  *  of the Diffie-Hellman-Merkle algorithm: | ||
|  |  * | ||
|  |  *  [1] Handbook of Applied Cryptography - 1997, Chapter 12 | ||
|  |  *      Menezes, van Oorschot and Vanstone | ||
|  |  * | ||
|  |  */ | ||
|  | 
 | ||
|  | #include "common.h"
 | ||
|  | 
 | ||
|  | #if defined(MBEDTLS_DHM_C)
 | ||
|  | 
 | ||
|  | #include "mbedtls/dhm.h"
 | ||
|  | #include "mbedtls/platform_util.h"
 | ||
|  | #include "mbedtls/error.h"
 | ||
|  | 
 | ||
|  | #include <string.h>
 | ||
|  | 
 | ||
|  | #if defined(MBEDTLS_PEM_PARSE_C)
 | ||
|  | #include "mbedtls/pem.h"
 | ||
|  | #endif
 | ||
|  | 
 | ||
|  | #if defined(MBEDTLS_ASN1_PARSE_C)
 | ||
|  | #include "mbedtls/asn1.h"
 | ||
|  | #endif
 | ||
|  | 
 | ||
|  | #include "mbedtls/platform.h"
 | ||
|  | 
 | ||
|  | #if !defined(MBEDTLS_DHM_ALT)
 | ||
|  | 
 | ||
|  | /*
 | ||
|  |  * helper to validate the mbedtls_mpi size and import it | ||
|  |  */ | ||
|  | static int dhm_read_bignum(mbedtls_mpi *X, | ||
|  |                            unsigned char **p, | ||
|  |                            const unsigned char *end) | ||
|  | { | ||
|  |     int ret, n; | ||
|  | 
 | ||
|  |     if (end - *p < 2) { | ||
|  |         return MBEDTLS_ERR_DHM_BAD_INPUT_DATA; | ||
|  |     } | ||
|  | 
 | ||
|  |     n = ((*p)[0] << 8) | (*p)[1]; | ||
|  |     (*p) += 2; | ||
|  | 
 | ||
|  |     if ((int) (end - *p) < n) { | ||
|  |         return MBEDTLS_ERR_DHM_BAD_INPUT_DATA; | ||
|  |     } | ||
|  | 
 | ||
|  |     if ((ret = mbedtls_mpi_read_binary(X, *p, n)) != 0) { | ||
|  |         return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_DHM_READ_PARAMS_FAILED, ret); | ||
|  |     } | ||
|  | 
 | ||
|  |     (*p) += n; | ||
|  | 
 | ||
|  |     return 0; | ||
|  | } | ||
|  | 
 | ||
|  | /*
 | ||
|  |  * Verify sanity of parameter with regards to P | ||
|  |  * | ||
|  |  * Parameter should be: 2 <= public_param <= P - 2 | ||
|  |  * | ||
|  |  * This means that we need to return an error if | ||
|  |  *              public_param < 2 or public_param > P-2 | ||
|  |  * | ||
|  |  * For more information on the attack, see: | ||
|  |  *  http://www.cl.cam.ac.uk/~rja14/Papers/psandqs.pdf
 | ||
|  |  *  http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2005-2643
 | ||
|  |  */ | ||
|  | static int dhm_check_range(const mbedtls_mpi *param, const mbedtls_mpi *P) | ||
|  | { | ||
|  |     mbedtls_mpi U; | ||
|  |     int ret = 0; | ||
|  | 
 | ||
|  |     mbedtls_mpi_init(&U); | ||
|  | 
 | ||
|  |     MBEDTLS_MPI_CHK(mbedtls_mpi_sub_int(&U, P, 2)); | ||
|  | 
 | ||
|  |     if (mbedtls_mpi_cmp_int(param, 2) < 0 || | ||
|  |         mbedtls_mpi_cmp_mpi(param, &U) > 0) { | ||
|  |         ret = MBEDTLS_ERR_DHM_BAD_INPUT_DATA; | ||
|  |     } | ||
|  | 
 | ||
|  | cleanup: | ||
|  |     mbedtls_mpi_free(&U); | ||
|  |     return ret; | ||
|  | } | ||
|  | 
 | ||
|  | void mbedtls_dhm_init(mbedtls_dhm_context *ctx) | ||
|  | { | ||
|  |     memset(ctx, 0, sizeof(mbedtls_dhm_context)); | ||
|  | } | ||
|  | 
 | ||
|  | size_t mbedtls_dhm_get_bitlen(const mbedtls_dhm_context *ctx) | ||
|  | { | ||
|  |     return mbedtls_mpi_bitlen(&ctx->P); | ||
|  | } | ||
|  | 
 | ||
|  | size_t mbedtls_dhm_get_len(const mbedtls_dhm_context *ctx) | ||
|  | { | ||
|  |     return mbedtls_mpi_size(&ctx->P); | ||
|  | } | ||
|  | 
 | ||
|  | int mbedtls_dhm_get_value(const mbedtls_dhm_context *ctx, | ||
|  |                           mbedtls_dhm_parameter param, | ||
|  |                           mbedtls_mpi *dest) | ||
|  | { | ||
|  |     const mbedtls_mpi *src = NULL; | ||
|  |     switch (param) { | ||
|  |         case MBEDTLS_DHM_PARAM_P: | ||
|  |             src = &ctx->P; | ||
|  |             break; | ||
|  |         case MBEDTLS_DHM_PARAM_G: | ||
|  |             src = &ctx->G; | ||
|  |             break; | ||
|  |         case MBEDTLS_DHM_PARAM_X: | ||
|  |             src = &ctx->X; | ||
|  |             break; | ||
|  |         case MBEDTLS_DHM_PARAM_GX: | ||
|  |             src = &ctx->GX; | ||
|  |             break; | ||
|  |         case MBEDTLS_DHM_PARAM_GY: | ||
|  |             src = &ctx->GY; | ||
|  |             break; | ||
|  |         case MBEDTLS_DHM_PARAM_K: | ||
|  |             src = &ctx->K; | ||
|  |             break; | ||
|  |         default: | ||
|  |             return MBEDTLS_ERR_DHM_BAD_INPUT_DATA; | ||
|  |     } | ||
|  |     return mbedtls_mpi_copy(dest, src); | ||
|  | } | ||
|  | 
 | ||
|  | /*
 | ||
|  |  * Parse the ServerKeyExchange parameters | ||
|  |  */ | ||
|  | int mbedtls_dhm_read_params(mbedtls_dhm_context *ctx, | ||
|  |                             unsigned char **p, | ||
|  |                             const unsigned char *end) | ||
|  | { | ||
|  |     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; | ||
|  | 
 | ||
|  |     if ((ret = dhm_read_bignum(&ctx->P,  p, end)) != 0 || | ||
|  |         (ret = dhm_read_bignum(&ctx->G,  p, end)) != 0 || | ||
|  |         (ret = dhm_read_bignum(&ctx->GY, p, end)) != 0) { | ||
|  |         return ret; | ||
|  |     } | ||
|  | 
 | ||
|  |     if ((ret = dhm_check_range(&ctx->GY, &ctx->P)) != 0) { | ||
|  |         return ret; | ||
|  |     } | ||
|  | 
 | ||
|  |     return 0; | ||
|  | } | ||
|  | 
 | ||
|  | /*
 | ||
|  |  * Pick a random R in the range [2, M-2] for blinding or key generation. | ||
|  |  */ | ||
|  | static int dhm_random_below(mbedtls_mpi *R, const mbedtls_mpi *M, | ||
|  |                             int (*f_rng)(void *, unsigned char *, size_t), void *p_rng) | ||
|  | { | ||
|  |     int ret; | ||
|  | 
 | ||
|  |     MBEDTLS_MPI_CHK(mbedtls_mpi_random(R, 3, M, f_rng, p_rng)); | ||
|  |     MBEDTLS_MPI_CHK(mbedtls_mpi_sub_int(R, R, 1)); | ||
|  | 
 | ||
|  | cleanup: | ||
|  |     return ret; | ||
|  | } | ||
|  | 
 | ||
|  | static int dhm_make_common(mbedtls_dhm_context *ctx, int x_size, | ||
|  |                            int (*f_rng)(void *, unsigned char *, size_t), | ||
|  |                            void *p_rng) | ||
|  | { | ||
|  |     int ret = 0; | ||
|  | 
 | ||
|  |     if (mbedtls_mpi_cmp_int(&ctx->P, 0) == 0) { | ||
|  |         return MBEDTLS_ERR_DHM_BAD_INPUT_DATA; | ||
|  |     } | ||
|  |     if (x_size < 0) { | ||
|  |         return MBEDTLS_ERR_DHM_BAD_INPUT_DATA; | ||
|  |     } | ||
|  | 
 | ||
|  |     if ((unsigned) x_size < mbedtls_mpi_size(&ctx->P)) { | ||
|  |         MBEDTLS_MPI_CHK(mbedtls_mpi_fill_random(&ctx->X, x_size, f_rng, p_rng)); | ||
|  |     } else { | ||
|  |         /* Generate X as large as possible ( <= P - 2 ) */ | ||
|  |         ret = dhm_random_below(&ctx->X, &ctx->P, f_rng, p_rng); | ||
|  |         if (ret == MBEDTLS_ERR_MPI_NOT_ACCEPTABLE) { | ||
|  |             return MBEDTLS_ERR_DHM_MAKE_PARAMS_FAILED; | ||
|  |         } | ||
|  |         if (ret != 0) { | ||
|  |             return ret; | ||
|  |         } | ||
|  |     } | ||
|  | 
 | ||
|  |     /*
 | ||
|  |      * Calculate GX = G^X mod P | ||
|  |      */ | ||
|  |     MBEDTLS_MPI_CHK(mbedtls_mpi_exp_mod(&ctx->GX, &ctx->G, &ctx->X, | ||
|  |                                         &ctx->P, &ctx->RP)); | ||
|  | 
 | ||
|  |     if ((ret = dhm_check_range(&ctx->GX, &ctx->P)) != 0) { | ||
|  |         return ret; | ||
|  |     } | ||
|  | 
 | ||
|  | cleanup: | ||
|  |     return ret; | ||
|  | } | ||
|  | 
 | ||
|  | /*
 | ||
|  |  * Setup and write the ServerKeyExchange parameters | ||
|  |  */ | ||
|  | int mbedtls_dhm_make_params(mbedtls_dhm_context *ctx, int x_size, | ||
|  |                             unsigned char *output, size_t *olen, | ||
|  |                             int (*f_rng)(void *, unsigned char *, size_t), | ||
|  |                             void *p_rng) | ||
|  | { | ||
|  |     int ret; | ||
|  |     size_t n1, n2, n3; | ||
|  |     unsigned char *p; | ||
|  | 
 | ||
|  |     ret = dhm_make_common(ctx, x_size, f_rng, p_rng); | ||
|  |     if (ret != 0) { | ||
|  |         goto cleanup; | ||
|  |     } | ||
|  | 
 | ||
|  |     /*
 | ||
|  |      * Export P, G, GX. RFC 5246 §4.4 states that "leading zero octets are | ||
|  |      * not required". We omit leading zeros for compactness. | ||
|  |      */ | ||
|  | #define DHM_MPI_EXPORT(X, n)                                          \
 | ||
|  |     do {                                                                \ | ||
|  |         MBEDTLS_MPI_CHK(mbedtls_mpi_write_binary((X),               \ | ||
|  |                                                  p + 2,               \ | ||
|  |                                                  (n)));           \ | ||
|  |         *p++ = MBEDTLS_BYTE_1(n);                                     \ | ||
|  |         *p++ = MBEDTLS_BYTE_0(n);                                     \ | ||
|  |         p += (n);                                                     \ | ||
|  |     } while (0) | ||
|  | 
 | ||
|  |     n1 = mbedtls_mpi_size(&ctx->P); | ||
|  |     n2 = mbedtls_mpi_size(&ctx->G); | ||
|  |     n3 = mbedtls_mpi_size(&ctx->GX); | ||
|  | 
 | ||
|  |     p = output; | ||
|  |     DHM_MPI_EXPORT(&ctx->P, n1); | ||
|  |     DHM_MPI_EXPORT(&ctx->G, n2); | ||
|  |     DHM_MPI_EXPORT(&ctx->GX, n3); | ||
|  | 
 | ||
|  |     *olen = p - output; | ||
|  | 
 | ||
|  | cleanup: | ||
|  |     if (ret != 0 && ret > -128) { | ||
|  |         ret = MBEDTLS_ERROR_ADD(MBEDTLS_ERR_DHM_MAKE_PARAMS_FAILED, ret); | ||
|  |     } | ||
|  |     return ret; | ||
|  | } | ||
|  | 
 | ||
|  | /*
 | ||
|  |  * Set prime modulus and generator | ||
|  |  */ | ||
|  | int mbedtls_dhm_set_group(mbedtls_dhm_context *ctx, | ||
|  |                           const mbedtls_mpi *P, | ||
|  |                           const mbedtls_mpi *G) | ||
|  | { | ||
|  |     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; | ||
|  | 
 | ||
|  |     if ((ret = mbedtls_mpi_copy(&ctx->P, P)) != 0 || | ||
|  |         (ret = mbedtls_mpi_copy(&ctx->G, G)) != 0) { | ||
|  |         return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_DHM_SET_GROUP_FAILED, ret); | ||
|  |     } | ||
|  | 
 | ||
|  |     return 0; | ||
|  | } | ||
|  | 
 | ||
|  | /*
 | ||
|  |  * Import the peer's public value G^Y | ||
|  |  */ | ||
|  | int mbedtls_dhm_read_public(mbedtls_dhm_context *ctx, | ||
|  |                             const unsigned char *input, size_t ilen) | ||
|  | { | ||
|  |     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; | ||
|  | 
 | ||
|  |     if (ilen < 1 || ilen > mbedtls_dhm_get_len(ctx)) { | ||
|  |         return MBEDTLS_ERR_DHM_BAD_INPUT_DATA; | ||
|  |     } | ||
|  | 
 | ||
|  |     if ((ret = mbedtls_mpi_read_binary(&ctx->GY, input, ilen)) != 0) { | ||
|  |         return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_DHM_READ_PUBLIC_FAILED, ret); | ||
|  |     } | ||
|  | 
 | ||
|  |     return 0; | ||
|  | } | ||
|  | 
 | ||
|  | /*
 | ||
|  |  * Create own private value X and export G^X | ||
|  |  */ | ||
|  | int mbedtls_dhm_make_public(mbedtls_dhm_context *ctx, int x_size, | ||
|  |                             unsigned char *output, size_t olen, | ||
|  |                             int (*f_rng)(void *, unsigned char *, size_t), | ||
|  |                             void *p_rng) | ||
|  | { | ||
|  |     int ret; | ||
|  | 
 | ||
|  |     if (olen < 1 || olen > mbedtls_dhm_get_len(ctx)) { | ||
|  |         return MBEDTLS_ERR_DHM_BAD_INPUT_DATA; | ||
|  |     } | ||
|  | 
 | ||
|  |     ret = dhm_make_common(ctx, x_size, f_rng, p_rng); | ||
|  |     if (ret == MBEDTLS_ERR_DHM_MAKE_PARAMS_FAILED) { | ||
|  |         return MBEDTLS_ERR_DHM_MAKE_PUBLIC_FAILED; | ||
|  |     } | ||
|  |     if (ret != 0) { | ||
|  |         goto cleanup; | ||
|  |     } | ||
|  | 
 | ||
|  |     MBEDTLS_MPI_CHK(mbedtls_mpi_write_binary(&ctx->GX, output, olen)); | ||
|  | 
 | ||
|  | cleanup: | ||
|  |     if (ret != 0 && ret > -128) { | ||
|  |         ret = MBEDTLS_ERROR_ADD(MBEDTLS_ERR_DHM_MAKE_PUBLIC_FAILED, ret); | ||
|  |     } | ||
|  |     return ret; | ||
|  | } | ||
|  | 
 | ||
|  | 
 | ||
|  | /*
 | ||
|  |  * Use the blinding method and optimisation suggested in section 10 of: | ||
|  |  *  KOCHER, Paul C. Timing attacks on implementations of Diffie-Hellman, RSA, | ||
|  |  *  DSS, and other systems. In : Advances in Cryptology-CRYPTO'96. Springer | ||
|  |  *  Berlin Heidelberg, 1996. p. 104-113. | ||
|  |  */ | ||
|  | static int dhm_update_blinding(mbedtls_dhm_context *ctx, | ||
|  |                                int (*f_rng)(void *, unsigned char *, size_t), void *p_rng) | ||
|  | { | ||
|  |     int ret; | ||
|  |     mbedtls_mpi R; | ||
|  | 
 | ||
|  |     mbedtls_mpi_init(&R); | ||
|  | 
 | ||
|  |     /*
 | ||
|  |      * Don't use any blinding the first time a particular X is used, | ||
|  |      * but remember it to use blinding next time. | ||
|  |      */ | ||
|  |     if (mbedtls_mpi_cmp_mpi(&ctx->X, &ctx->pX) != 0) { | ||
|  |         MBEDTLS_MPI_CHK(mbedtls_mpi_copy(&ctx->pX, &ctx->X)); | ||
|  |         MBEDTLS_MPI_CHK(mbedtls_mpi_lset(&ctx->Vi, 1)); | ||
|  |         MBEDTLS_MPI_CHK(mbedtls_mpi_lset(&ctx->Vf, 1)); | ||
|  | 
 | ||
|  |         return 0; | ||
|  |     } | ||
|  | 
 | ||
|  |     /*
 | ||
|  |      * Ok, we need blinding. Can we re-use existing values? | ||
|  |      * If yes, just update them by squaring them. | ||
|  |      */ | ||
|  |     if (mbedtls_mpi_cmp_int(&ctx->Vi, 1) != 0) { | ||
|  |         MBEDTLS_MPI_CHK(mbedtls_mpi_mul_mpi(&ctx->Vi, &ctx->Vi, &ctx->Vi)); | ||
|  |         MBEDTLS_MPI_CHK(mbedtls_mpi_mod_mpi(&ctx->Vi, &ctx->Vi, &ctx->P)); | ||
|  | 
 | ||
|  |         MBEDTLS_MPI_CHK(mbedtls_mpi_mul_mpi(&ctx->Vf, &ctx->Vf, &ctx->Vf)); | ||
|  |         MBEDTLS_MPI_CHK(mbedtls_mpi_mod_mpi(&ctx->Vf, &ctx->Vf, &ctx->P)); | ||
|  | 
 | ||
|  |         return 0; | ||
|  |     } | ||
|  | 
 | ||
|  |     /*
 | ||
|  |      * We need to generate blinding values from scratch | ||
|  |      */ | ||
|  | 
 | ||
|  |     /* Vi = random( 2, P-2 ) */ | ||
|  |     MBEDTLS_MPI_CHK(dhm_random_below(&ctx->Vi, &ctx->P, f_rng, p_rng)); | ||
|  | 
 | ||
|  |     /* Vf = Vi^-X mod P
 | ||
|  |      * First compute Vi^-1 = R * (R Vi)^-1, (avoiding leaks from inv_mod), | ||
|  |      * then elevate to the Xth power. */ | ||
|  |     MBEDTLS_MPI_CHK(dhm_random_below(&R, &ctx->P, f_rng, p_rng)); | ||
|  |     MBEDTLS_MPI_CHK(mbedtls_mpi_mul_mpi(&ctx->Vf, &ctx->Vi, &R)); | ||
|  |     MBEDTLS_MPI_CHK(mbedtls_mpi_mod_mpi(&ctx->Vf, &ctx->Vf, &ctx->P)); | ||
|  |     MBEDTLS_MPI_CHK(mbedtls_mpi_inv_mod(&ctx->Vf, &ctx->Vf, &ctx->P)); | ||
|  |     MBEDTLS_MPI_CHK(mbedtls_mpi_mul_mpi(&ctx->Vf, &ctx->Vf, &R)); | ||
|  |     MBEDTLS_MPI_CHK(mbedtls_mpi_mod_mpi(&ctx->Vf, &ctx->Vf, &ctx->P)); | ||
|  | 
 | ||
|  |     MBEDTLS_MPI_CHK(mbedtls_mpi_exp_mod(&ctx->Vf, &ctx->Vf, &ctx->X, &ctx->P, &ctx->RP)); | ||
|  | 
 | ||
|  | cleanup: | ||
|  |     mbedtls_mpi_free(&R); | ||
|  | 
 | ||
|  |     return ret; | ||
|  | } | ||
|  | 
 | ||
|  | /*
 | ||
|  |  * Derive and export the shared secret (G^Y)^X mod P | ||
|  |  */ | ||
|  | int mbedtls_dhm_calc_secret(mbedtls_dhm_context *ctx, | ||
|  |                             unsigned char *output, size_t output_size, size_t *olen, | ||
|  |                             int (*f_rng)(void *, unsigned char *, size_t), | ||
|  |                             void *p_rng) | ||
|  | { | ||
|  |     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; | ||
|  |     mbedtls_mpi GYb; | ||
|  | 
 | ||
|  |     if (f_rng == NULL) { | ||
|  |         return MBEDTLS_ERR_DHM_BAD_INPUT_DATA; | ||
|  |     } | ||
|  | 
 | ||
|  |     if (output_size < mbedtls_dhm_get_len(ctx)) { | ||
|  |         return MBEDTLS_ERR_DHM_BAD_INPUT_DATA; | ||
|  |     } | ||
|  | 
 | ||
|  |     if ((ret = dhm_check_range(&ctx->GY, &ctx->P)) != 0) { | ||
|  |         return ret; | ||
|  |     } | ||
|  | 
 | ||
|  |     mbedtls_mpi_init(&GYb); | ||
|  | 
 | ||
|  |     /* Blind peer's value */ | ||
|  |     MBEDTLS_MPI_CHK(dhm_update_blinding(ctx, f_rng, p_rng)); | ||
|  |     MBEDTLS_MPI_CHK(mbedtls_mpi_mul_mpi(&GYb, &ctx->GY, &ctx->Vi)); | ||
|  |     MBEDTLS_MPI_CHK(mbedtls_mpi_mod_mpi(&GYb, &GYb, &ctx->P)); | ||
|  | 
 | ||
|  |     /* Do modular exponentiation */ | ||
|  |     MBEDTLS_MPI_CHK(mbedtls_mpi_exp_mod(&ctx->K, &GYb, &ctx->X, | ||
|  |                                         &ctx->P, &ctx->RP)); | ||
|  | 
 | ||
|  |     /* Unblind secret value */ | ||
|  |     MBEDTLS_MPI_CHK(mbedtls_mpi_mul_mpi(&ctx->K, &ctx->K, &ctx->Vf)); | ||
|  |     MBEDTLS_MPI_CHK(mbedtls_mpi_mod_mpi(&ctx->K, &ctx->K, &ctx->P)); | ||
|  | 
 | ||
|  |     /* Output the secret without any leading zero byte. This is mandatory
 | ||
|  |      * for TLS per RFC 5246 §8.1.2. */ | ||
|  |     *olen = mbedtls_mpi_size(&ctx->K); | ||
|  |     MBEDTLS_MPI_CHK(mbedtls_mpi_write_binary(&ctx->K, output, *olen)); | ||
|  | 
 | ||
|  | cleanup: | ||
|  |     mbedtls_mpi_free(&GYb); | ||
|  | 
 | ||
|  |     if (ret != 0) { | ||
|  |         return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_DHM_CALC_SECRET_FAILED, ret); | ||
|  |     } | ||
|  | 
 | ||
|  |     return 0; | ||
|  | } | ||
|  | 
 | ||
|  | /*
 | ||
|  |  * Free the components of a DHM key | ||
|  |  */ | ||
|  | void mbedtls_dhm_free(mbedtls_dhm_context *ctx) | ||
|  | { | ||
|  |     if (ctx == NULL) { | ||
|  |         return; | ||
|  |     } | ||
|  | 
 | ||
|  |     mbedtls_mpi_free(&ctx->pX); | ||
|  |     mbedtls_mpi_free(&ctx->Vf); | ||
|  |     mbedtls_mpi_free(&ctx->Vi); | ||
|  |     mbedtls_mpi_free(&ctx->RP); | ||
|  |     mbedtls_mpi_free(&ctx->K); | ||
|  |     mbedtls_mpi_free(&ctx->GY); | ||
|  |     mbedtls_mpi_free(&ctx->GX); | ||
|  |     mbedtls_mpi_free(&ctx->X); | ||
|  |     mbedtls_mpi_free(&ctx->G); | ||
|  |     mbedtls_mpi_free(&ctx->P); | ||
|  | 
 | ||
|  |     mbedtls_platform_zeroize(ctx, sizeof(mbedtls_dhm_context)); | ||
|  | } | ||
|  | 
 | ||
|  | #if defined(MBEDTLS_ASN1_PARSE_C)
 | ||
|  | /*
 | ||
|  |  * Parse DHM parameters | ||
|  |  */ | ||
|  | int mbedtls_dhm_parse_dhm(mbedtls_dhm_context *dhm, const unsigned char *dhmin, | ||
|  |                           size_t dhminlen) | ||
|  | { | ||
|  |     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; | ||
|  |     size_t len; | ||
|  |     unsigned char *p, *end; | ||
|  | #if defined(MBEDTLS_PEM_PARSE_C)
 | ||
|  |     mbedtls_pem_context pem; | ||
|  | #endif /* MBEDTLS_PEM_PARSE_C */
 | ||
|  | 
 | ||
|  | #if defined(MBEDTLS_PEM_PARSE_C)
 | ||
|  |     mbedtls_pem_init(&pem); | ||
|  | 
 | ||
|  |     /* Avoid calling mbedtls_pem_read_buffer() on non-null-terminated string */ | ||
|  |     if (dhminlen == 0 || dhmin[dhminlen - 1] != '\0') { | ||
|  |         ret = MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT; | ||
|  |     } else { | ||
|  |         ret = mbedtls_pem_read_buffer(&pem, | ||
|  |                                       "-----BEGIN DH PARAMETERS-----", | ||
|  |                                       "-----END DH PARAMETERS-----", | ||
|  |                                       dhmin, NULL, 0, &dhminlen); | ||
|  |     } | ||
|  | 
 | ||
|  |     if (ret == 0) { | ||
|  |         /*
 | ||
|  |          * Was PEM encoded | ||
|  |          */ | ||
|  |         dhminlen = pem.buflen; | ||
|  |     } else if (ret != MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT) { | ||
|  |         goto exit; | ||
|  |     } | ||
|  | 
 | ||
|  |     p = (ret == 0) ? pem.buf : (unsigned char *) dhmin; | ||
|  | #else
 | ||
|  |     p = (unsigned char *) dhmin; | ||
|  | #endif /* MBEDTLS_PEM_PARSE_C */
 | ||
|  |     end = p + dhminlen; | ||
|  | 
 | ||
|  |     /*
 | ||
|  |      *  DHParams ::= SEQUENCE { | ||
|  |      *      prime              INTEGER,  -- P | ||
|  |      *      generator          INTEGER,  -- g | ||
|  |      *      privateValueLength INTEGER OPTIONAL | ||
|  |      *  } | ||
|  |      */ | ||
|  |     if ((ret = mbedtls_asn1_get_tag(&p, end, &len, | ||
|  |                                     MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE)) != 0) { | ||
|  |         ret = MBEDTLS_ERROR_ADD(MBEDTLS_ERR_DHM_INVALID_FORMAT, ret); | ||
|  |         goto exit; | ||
|  |     } | ||
|  | 
 | ||
|  |     end = p + len; | ||
|  | 
 | ||
|  |     if ((ret = mbedtls_asn1_get_mpi(&p, end, &dhm->P)) != 0 || | ||
|  |         (ret = mbedtls_asn1_get_mpi(&p, end, &dhm->G)) != 0) { | ||
|  |         ret = MBEDTLS_ERROR_ADD(MBEDTLS_ERR_DHM_INVALID_FORMAT, ret); | ||
|  |         goto exit; | ||
|  |     } | ||
|  | 
 | ||
|  |     if (p != end) { | ||
|  |         /* This might be the optional privateValueLength.
 | ||
|  |          * If so, we can cleanly discard it */ | ||
|  |         mbedtls_mpi rec; | ||
|  |         mbedtls_mpi_init(&rec); | ||
|  |         ret = mbedtls_asn1_get_mpi(&p, end, &rec); | ||
|  |         mbedtls_mpi_free(&rec); | ||
|  |         if (ret != 0) { | ||
|  |             ret = MBEDTLS_ERROR_ADD(MBEDTLS_ERR_DHM_INVALID_FORMAT, ret); | ||
|  |             goto exit; | ||
|  |         } | ||
|  |         if (p != end) { | ||
|  |             ret = MBEDTLS_ERROR_ADD(MBEDTLS_ERR_DHM_INVALID_FORMAT, | ||
|  |                                     MBEDTLS_ERR_ASN1_LENGTH_MISMATCH); | ||
|  |             goto exit; | ||
|  |         } | ||
|  |     } | ||
|  | 
 | ||
|  |     ret = 0; | ||
|  | 
 | ||
|  | exit: | ||
|  | #if defined(MBEDTLS_PEM_PARSE_C)
 | ||
|  |     mbedtls_pem_free(&pem); | ||
|  | #endif
 | ||
|  |     if (ret != 0) { | ||
|  |         mbedtls_dhm_free(dhm); | ||
|  |     } | ||
|  | 
 | ||
|  |     return ret; | ||
|  | } | ||
|  | 
 | ||
|  | #if defined(MBEDTLS_FS_IO)
 | ||
|  | /*
 | ||
|  |  * Load all data from a file into a given buffer. | ||
|  |  * | ||
|  |  * The file is expected to contain either PEM or DER encoded data. | ||
|  |  * A terminating null byte is always appended. It is included in the announced | ||
|  |  * length only if the data looks like it is PEM encoded. | ||
|  |  */ | ||
|  | static int load_file(const char *path, unsigned char **buf, size_t *n) | ||
|  | { | ||
|  |     FILE *f; | ||
|  |     long size; | ||
|  | 
 | ||
|  |     if ((f = fopen(path, "rb")) == NULL) { | ||
|  |         return MBEDTLS_ERR_DHM_FILE_IO_ERROR; | ||
|  |     } | ||
|  |     /* The data loaded here is public, so don't bother disabling buffering. */ | ||
|  | 
 | ||
|  |     fseek(f, 0, SEEK_END); | ||
|  |     if ((size = ftell(f)) == -1) { | ||
|  |         fclose(f); | ||
|  |         return MBEDTLS_ERR_DHM_FILE_IO_ERROR; | ||
|  |     } | ||
|  |     fseek(f, 0, SEEK_SET); | ||
|  | 
 | ||
|  |     *n = (size_t) size; | ||
|  | 
 | ||
|  |     if (*n + 1 == 0 || | ||
|  |         (*buf = mbedtls_calloc(1, *n + 1)) == NULL) { | ||
|  |         fclose(f); | ||
|  |         return MBEDTLS_ERR_DHM_ALLOC_FAILED; | ||
|  |     } | ||
|  | 
 | ||
|  |     if (fread(*buf, 1, *n, f) != *n) { | ||
|  |         fclose(f); | ||
|  | 
 | ||
|  |         mbedtls_zeroize_and_free(*buf, *n + 1); | ||
|  | 
 | ||
|  |         return MBEDTLS_ERR_DHM_FILE_IO_ERROR; | ||
|  |     } | ||
|  | 
 | ||
|  |     fclose(f); | ||
|  | 
 | ||
|  |     (*buf)[*n] = '\0'; | ||
|  | 
 | ||
|  |     if (strstr((const char *) *buf, "-----BEGIN ") != NULL) { | ||
|  |         ++*n; | ||
|  |     } | ||
|  | 
 | ||
|  |     return 0; | ||
|  | } | ||
|  | 
 | ||
|  | /*
 | ||
|  |  * Load and parse DHM parameters | ||
|  |  */ | ||
|  | int mbedtls_dhm_parse_dhmfile(mbedtls_dhm_context *dhm, const char *path) | ||
|  | { | ||
|  |     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; | ||
|  |     size_t n; | ||
|  |     unsigned char *buf; | ||
|  | 
 | ||
|  |     if ((ret = load_file(path, &buf, &n)) != 0) { | ||
|  |         return ret; | ||
|  |     } | ||
|  | 
 | ||
|  |     ret = mbedtls_dhm_parse_dhm(dhm, buf, n); | ||
|  | 
 | ||
|  |     mbedtls_zeroize_and_free(buf, n); | ||
|  | 
 | ||
|  |     return ret; | ||
|  | } | ||
|  | #endif /* MBEDTLS_FS_IO */
 | ||
|  | #endif /* MBEDTLS_ASN1_PARSE_C */
 | ||
|  | #endif /* MBEDTLS_DHM_ALT */
 | ||
|  | 
 | ||
|  | #if defined(MBEDTLS_SELF_TEST)
 | ||
|  | 
 | ||
|  | #if defined(MBEDTLS_PEM_PARSE_C)
 | ||
|  | static const char mbedtls_test_dhm_params[] = | ||
|  |     "-----BEGIN DH PARAMETERS-----\r\n" | ||
|  |     "MIGHAoGBAJ419DBEOgmQTzo5qXl5fQcN9TN455wkOL7052HzxxRVMyhYmwQcgJvh\r\n" | ||
|  |     "1sa18fyfR9OiVEMYglOpkqVoGLN7qd5aQNNi5W7/C+VBdHTBJcGZJyyP5B3qcz32\r\n" | ||
|  |     "9mLJKudlVudV0Qxk5qUJaPZ/xupz0NyoVpviuiBOI1gNi8ovSXWzAgEC\r\n" | ||
|  |     "-----END DH PARAMETERS-----\r\n"; | ||
|  | #else /* MBEDTLS_PEM_PARSE_C */
 | ||
|  | static const char mbedtls_test_dhm_params[] = { | ||
|  |     0x30, 0x81, 0x87, 0x02, 0x81, 0x81, 0x00, 0x9e, 0x35, 0xf4, 0x30, 0x44, | ||
|  |     0x3a, 0x09, 0x90, 0x4f, 0x3a, 0x39, 0xa9, 0x79, 0x79, 0x7d, 0x07, 0x0d, | ||
|  |     0xf5, 0x33, 0x78, 0xe7, 0x9c, 0x24, 0x38, 0xbe, 0xf4, 0xe7, 0x61, 0xf3, | ||
|  |     0xc7, 0x14, 0x55, 0x33, 0x28, 0x58, 0x9b, 0x04, 0x1c, 0x80, 0x9b, 0xe1, | ||
|  |     0xd6, 0xc6, 0xb5, 0xf1, 0xfc, 0x9f, 0x47, 0xd3, 0xa2, 0x54, 0x43, 0x18, | ||
|  |     0x82, 0x53, 0xa9, 0x92, 0xa5, 0x68, 0x18, 0xb3, 0x7b, 0xa9, 0xde, 0x5a, | ||
|  |     0x40, 0xd3, 0x62, 0xe5, 0x6e, 0xff, 0x0b, 0xe5, 0x41, 0x74, 0x74, 0xc1, | ||
|  |     0x25, 0xc1, 0x99, 0x27, 0x2c, 0x8f, 0xe4, 0x1d, 0xea, 0x73, 0x3d, 0xf6, | ||
|  |     0xf6, 0x62, 0xc9, 0x2a, 0xe7, 0x65, 0x56, 0xe7, 0x55, 0xd1, 0x0c, 0x64, | ||
|  |     0xe6, 0xa5, 0x09, 0x68, 0xf6, 0x7f, 0xc6, 0xea, 0x73, 0xd0, 0xdc, 0xa8, | ||
|  |     0x56, 0x9b, 0xe2, 0xba, 0x20, 0x4e, 0x23, 0x58, 0x0d, 0x8b, 0xca, 0x2f, | ||
|  |     0x49, 0x75, 0xb3, 0x02, 0x01, 0x02 | ||
|  | }; | ||
|  | #endif /* MBEDTLS_PEM_PARSE_C */
 | ||
|  | 
 | ||
|  | static const size_t mbedtls_test_dhm_params_len = sizeof(mbedtls_test_dhm_params); | ||
|  | 
 | ||
|  | /*
 | ||
|  |  * Checkup routine | ||
|  |  */ | ||
|  | int mbedtls_dhm_self_test(int verbose) | ||
|  | { | ||
|  |     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; | ||
|  |     mbedtls_dhm_context dhm; | ||
|  | 
 | ||
|  |     mbedtls_dhm_init(&dhm); | ||
|  | 
 | ||
|  |     if (verbose != 0) { | ||
|  |         mbedtls_printf("  DHM parameter load: "); | ||
|  |     } | ||
|  | 
 | ||
|  |     if ((ret = mbedtls_dhm_parse_dhm(&dhm, | ||
|  |                                      (const unsigned char *) mbedtls_test_dhm_params, | ||
|  |                                      mbedtls_test_dhm_params_len)) != 0) { | ||
|  |         if (verbose != 0) { | ||
|  |             mbedtls_printf("failed\n"); | ||
|  |         } | ||
|  | 
 | ||
|  |         ret = 1; | ||
|  |         goto exit; | ||
|  |     } | ||
|  | 
 | ||
|  |     if (verbose != 0) { | ||
|  |         mbedtls_printf("passed\n\n"); | ||
|  |     } | ||
|  | 
 | ||
|  | exit: | ||
|  |     mbedtls_dhm_free(&dhm); | ||
|  | 
 | ||
|  |     return ret; | ||
|  | } | ||
|  | 
 | ||
|  | #endif /* MBEDTLS_SELF_TEST */
 | ||
|  | 
 | ||
|  | #endif /* MBEDTLS_DHM_C */
 |