blob: d6e4990a9b13c2fb007cd1936275cd2c091d9c07 [file] [log] [blame]
Paul Bakker5121ce52009-01-03 21:22:43 +00001/*
2 * Diffie-Hellman-Merkle key exchange (client side)
3 *
Bence Szépkúti1e148272020-08-07 13:07:28 +02004 * Copyright The Mbed TLS Contributors
Manuel Pégourié-Gonnard37ff1402015-09-04 14:21:07 +02005 * SPDX-License-Identifier: Apache-2.0
6 *
7 * Licensed under the Apache License, Version 2.0 (the "License"); you may
8 * not use this file except in compliance with the License.
9 * You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing, software
14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 * See the License for the specific language governing permissions and
17 * limitations under the License.
Paul Bakker5121ce52009-01-03 21:22:43 +000018 */
19
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +020020#if !defined(MBEDTLS_CONFIG_FILE)
Manuel Pégourié-Gonnard7f809972015-03-09 17:05:11 +000021#include "mbedtls/config.h"
Manuel Pégourié-Gonnardcef4ad22014-04-29 12:39:06 +020022#else
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +020023#include MBEDTLS_CONFIG_FILE
Manuel Pégourié-Gonnardcef4ad22014-04-29 12:39:06 +020024#endif
Paul Bakker5121ce52009-01-03 21:22:43 +000025
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +020026#if defined(MBEDTLS_PLATFORM_C)
Manuel Pégourié-Gonnard7f809972015-03-09 17:05:11 +000027#include "mbedtls/platform.h"
Rich Evansf90016a2015-01-19 14:26:37 +000028#else
Rich Evans18b78c72015-02-11 14:06:19 +000029#include <stdio.h>
Andres Amaya Garcia898841d2018-04-29 19:23:39 +010030#include <stdlib.h>
31#define mbedtls_printf printf
32#define mbedtls_time_t time_t
Manuel Pégourié-Gonnard3ef6a6d2018-12-10 14:31:45 +010033#define mbedtls_exit exit
Andres Amaya Garcia7d429652018-04-30 22:42:33 +010034#define MBEDTLS_EXIT_SUCCESS EXIT_SUCCESS
Andres Amaya Garcia898841d2018-04-29 19:23:39 +010035#define MBEDTLS_EXIT_FAILURE EXIT_FAILURE
36#endif /* MBEDTLS_PLATFORM_C */
Rich Evansf90016a2015-01-19 14:26:37 +000037
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +020038#if defined(MBEDTLS_AES_C) && defined(MBEDTLS_DHM_C) && \
39 defined(MBEDTLS_ENTROPY_C) && defined(MBEDTLS_NET_C) && \
40 defined(MBEDTLS_RSA_C) && defined(MBEDTLS_SHA256_C) && \
Janos Follath9fe6f922016-10-07 14:17:56 +010041 defined(MBEDTLS_FS_IO) && defined(MBEDTLS_CTR_DRBG_C) && \
42 defined(MBEDTLS_SHA1_C)
Andres AG788aa4a2016-09-14 14:32:09 +010043#include "mbedtls/net_sockets.h"
Manuel Pégourié-Gonnard7f809972015-03-09 17:05:11 +000044#include "mbedtls/aes.h"
45#include "mbedtls/dhm.h"
46#include "mbedtls/rsa.h"
47#include "mbedtls/sha1.h"
48#include "mbedtls/entropy.h"
49#include "mbedtls/ctr_drbg.h"
Paul Bakker5121ce52009-01-03 21:22:43 +000050
Rich Evans18b78c72015-02-11 14:06:19 +000051#include <stdio.h>
52#include <string.h>
53#endif
54
Paul Bakker5121ce52009-01-03 21:22:43 +000055#define SERVER_NAME "localhost"
Manuel Pégourié-Gonnardc0d74942015-06-23 12:30:57 +020056#define SERVER_PORT "11999"
Paul Bakker5121ce52009-01-03 21:22:43 +000057
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +020058#if !defined(MBEDTLS_AES_C) || !defined(MBEDTLS_DHM_C) || \
59 !defined(MBEDTLS_ENTROPY_C) || !defined(MBEDTLS_NET_C) || \
60 !defined(MBEDTLS_RSA_C) || !defined(MBEDTLS_SHA256_C) || \
Janos Follath9fe6f922016-10-07 14:17:56 +010061 !defined(MBEDTLS_FS_IO) || !defined(MBEDTLS_CTR_DRBG_C) || \
62 !defined(MBEDTLS_SHA1_C)
Rich Evans85b05ec2015-02-12 11:37:29 +000063int main( void )
Paul Bakker5690efc2011-05-26 13:16:06 +000064{
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +020065 mbedtls_printf("MBEDTLS_AES_C and/or MBEDTLS_DHM_C and/or MBEDTLS_ENTROPY_C "
66 "and/or MBEDTLS_NET_C and/or MBEDTLS_RSA_C and/or "
67 "MBEDTLS_SHA256_C and/or MBEDTLS_FS_IO and/or "
68 "MBEDTLS_CTR_DRBG_C not defined.\n");
Krzysztof Stachowiak5e1b1952019-04-24 14:24:46 +020069 mbedtls_exit( 0 );
Paul Bakker5690efc2011-05-26 13:16:06 +000070}
71#else
Simon Butcher63cb97e2018-12-06 17:43:31 +000072
Simon Butcher63cb97e2018-12-06 17:43:31 +000073
Rich Evans85b05ec2015-02-12 11:37:29 +000074int main( void )
Paul Bakker5121ce52009-01-03 21:22:43 +000075{
76 FILE *f;
77
Andres Amaya Garcia898841d2018-04-29 19:23:39 +010078 int ret = 1;
79 int exit_code = MBEDTLS_EXIT_FAILURE;
Paul Bakker23986e52011-04-24 08:57:21 +000080 size_t n, buflen;
Manuel Pégourié-Gonnard5db64322015-06-30 15:40:39 +020081 mbedtls_net_context server_fd;
Paul Bakker5121ce52009-01-03 21:22:43 +000082
83 unsigned char *p, *end;
Paul Bakker520ea912012-10-24 14:17:01 +000084 unsigned char buf[2048];
Manuel Pégourié-Gonnard102a6202015-08-27 21:51:44 +020085 unsigned char hash[32];
Paul Bakkeref3f8c72013-06-24 13:01:08 +020086 const char *pers = "dh_client";
Paul Bakker5121ce52009-01-03 21:22:43 +000087
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +020088 mbedtls_entropy_context entropy;
89 mbedtls_ctr_drbg_context ctr_drbg;
90 mbedtls_rsa_context rsa;
91 mbedtls_dhm_context dhm;
92 mbedtls_aes_context aes;
Paul Bakker5121ce52009-01-03 21:22:43 +000093
Manuel Pégourié-Gonnard5db64322015-06-30 15:40:39 +020094 mbedtls_net_init( &server_fd );
95 mbedtls_rsa_init( &rsa, MBEDTLS_RSA_PKCS_V15, MBEDTLS_MD_SHA256 );
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +020096 mbedtls_dhm_init( &dhm );
97 mbedtls_aes_init( &aes );
Manuel Pégourié-Gonnardec160c02015-04-28 22:52:30 +020098 mbedtls_ctr_drbg_init( &ctr_drbg );
Paul Bakker8cfd9d82014-06-18 11:16:11 +020099
Paul Bakker5121ce52009-01-03 21:22:43 +0000100 /*
101 * 1. Setup the RNG
102 */
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200103 mbedtls_printf( "\n . Seeding the random number generator" );
Paul Bakker5121ce52009-01-03 21:22:43 +0000104 fflush( stdout );
105
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200106 mbedtls_entropy_init( &entropy );
Manuel Pégourié-Gonnardec160c02015-04-28 22:52:30 +0200107 if( ( ret = mbedtls_ctr_drbg_seed( &ctr_drbg, mbedtls_entropy_func, &entropy,
Paul Bakkeref3f8c72013-06-24 13:01:08 +0200108 (const unsigned char *) pers,
109 strlen( pers ) ) ) != 0 )
Paul Bakker508ad5a2011-12-04 17:09:26 +0000110 {
Manuel Pégourié-Gonnardec160c02015-04-28 22:52:30 +0200111 mbedtls_printf( " failed\n ! mbedtls_ctr_drbg_seed returned %d\n", ret );
Paul Bakker508ad5a2011-12-04 17:09:26 +0000112 goto exit;
113 }
Paul Bakker5121ce52009-01-03 21:22:43 +0000114
115 /*
116 * 2. Read the server's public RSA key
117 */
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200118 mbedtls_printf( "\n . Reading public key from rsa_pub.txt" );
Paul Bakker5121ce52009-01-03 21:22:43 +0000119 fflush( stdout );
120
121 if( ( f = fopen( "rsa_pub.txt", "rb" ) ) == NULL )
122 {
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200123 mbedtls_printf( " failed\n ! Could not open rsa_pub.txt\n" \
Paul Bakker5121ce52009-01-03 21:22:43 +0000124 " ! Please run rsa_genkey first\n\n" );
125 goto exit;
126 }
127
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200128 mbedtls_rsa_init( &rsa, MBEDTLS_RSA_PKCS_V15, 0 );
Paul Bakker5121ce52009-01-03 21:22:43 +0000129
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200130 if( ( ret = mbedtls_mpi_read_file( &rsa.N, 16, f ) ) != 0 ||
131 ( ret = mbedtls_mpi_read_file( &rsa.E, 16, f ) ) != 0 )
Paul Bakker5121ce52009-01-03 21:22:43 +0000132 {
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200133 mbedtls_printf( " failed\n ! mbedtls_mpi_read_file returned %d\n\n", ret );
Janos Follath98e28a72016-05-31 14:03:54 +0100134 fclose( f );
Paul Bakker5121ce52009-01-03 21:22:43 +0000135 goto exit;
136 }
137
Manuel Pégourié-Gonnardc0696c22015-06-18 16:47:17 +0200138 rsa.len = ( mbedtls_mpi_bitlen( &rsa.N ) + 7 ) >> 3;
Paul Bakker5121ce52009-01-03 21:22:43 +0000139
140 fclose( f );
141
142 /*
143 * 3. Initiate the connection
144 */
Manuel Pégourié-Gonnardc0d74942015-06-23 12:30:57 +0200145 mbedtls_printf( "\n . Connecting to tcp/%s/%s", SERVER_NAME,
Paul Bakker5121ce52009-01-03 21:22:43 +0000146 SERVER_PORT );
147 fflush( stdout );
148
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200149 if( ( ret = mbedtls_net_connect( &server_fd, SERVER_NAME,
150 SERVER_PORT, MBEDTLS_NET_PROTO_TCP ) ) != 0 )
Paul Bakker5121ce52009-01-03 21:22:43 +0000151 {
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200152 mbedtls_printf( " failed\n ! mbedtls_net_connect returned %d\n\n", ret );
Paul Bakker5121ce52009-01-03 21:22:43 +0000153 goto exit;
154 }
155
156 /*
157 * 4a. First get the buffer length
158 */
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200159 mbedtls_printf( "\n . Receiving the server's DH parameters" );
Paul Bakker5121ce52009-01-03 21:22:43 +0000160 fflush( stdout );
161
162 memset( buf, 0, sizeof( buf ) );
163
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200164 if( ( ret = mbedtls_net_recv( &server_fd, buf, 2 ) ) != 2 )
Paul Bakker5121ce52009-01-03 21:22:43 +0000165 {
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200166 mbedtls_printf( " failed\n ! mbedtls_net_recv returned %d\n\n", ret );
Paul Bakker5121ce52009-01-03 21:22:43 +0000167 goto exit;
168 }
169
170 n = buflen = ( buf[0] << 8 ) | buf[1];
Paul Bakker23986e52011-04-24 08:57:21 +0000171 if( buflen < 1 || buflen > sizeof( buf ) )
Paul Bakker5121ce52009-01-03 21:22:43 +0000172 {
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200173 mbedtls_printf( " failed\n ! Got an invalid buffer length\n\n" );
Paul Bakker5121ce52009-01-03 21:22:43 +0000174 goto exit;
175 }
176
177 /*
178 * 4b. Get the DHM parameters: P, G and Ys = G^Xs mod P
179 */
180 memset( buf, 0, sizeof( buf ) );
181
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200182 if( ( ret = mbedtls_net_recv( &server_fd, buf, n ) ) != (int) n )
Paul Bakker5121ce52009-01-03 21:22:43 +0000183 {
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200184 mbedtls_printf( " failed\n ! mbedtls_net_recv returned %d\n\n", ret );
Paul Bakker5121ce52009-01-03 21:22:43 +0000185 goto exit;
186 }
187
188 p = buf, end = buf + buflen;
189
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200190 if( ( ret = mbedtls_dhm_read_params( &dhm, &p, end ) ) != 0 )
Paul Bakker5121ce52009-01-03 21:22:43 +0000191 {
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200192 mbedtls_printf( " failed\n ! mbedtls_dhm_read_params returned %d\n\n", ret );
Paul Bakker5121ce52009-01-03 21:22:43 +0000193 goto exit;
194 }
195
Paul Bakker520ea912012-10-24 14:17:01 +0000196 if( dhm.len < 64 || dhm.len > 512 )
Paul Bakker5121ce52009-01-03 21:22:43 +0000197 {
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200198 mbedtls_printf( " failed\n ! Invalid DHM modulus size\n\n" );
Paul Bakker5121ce52009-01-03 21:22:43 +0000199 goto exit;
200 }
201
202 /*
203 * 5. Check that the server's RSA signature matches
Manuel Pégourié-Gonnard6f60cd82015-02-10 10:47:03 +0000204 * the SHA-256 hash of (P,G,Ys)
Paul Bakker5121ce52009-01-03 21:22:43 +0000205 */
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200206 mbedtls_printf( "\n . Verifying the server's RSA signature" );
Paul Bakker5121ce52009-01-03 21:22:43 +0000207 fflush( stdout );
208
Paul Bakker88f17b82012-04-26 18:52:13 +0000209 p += 2;
210
Paul Bakker23986e52011-04-24 08:57:21 +0000211 if( ( n = (size_t) ( end - p ) ) != rsa.len )
Paul Bakker5121ce52009-01-03 21:22:43 +0000212 {
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200213 mbedtls_printf( " failed\n ! Invalid RSA signature size\n\n" );
Paul Bakker5121ce52009-01-03 21:22:43 +0000214 goto exit;
215 }
216
Gilles Peskine9e4f77c2018-01-22 11:48:08 +0100217 if( ( ret = mbedtls_sha1_ret( buf, (int)( p - 2 - buf ), hash ) ) != 0 )
Andres Amaya Garcia1ff60f42017-06-28 13:26:36 +0100218 {
Gilles Peskine9e4f77c2018-01-22 11:48:08 +0100219 mbedtls_printf( " failed\n ! mbedtls_sha1_ret returned %d\n\n", ret );
Andres Amaya Garcia1ff60f42017-06-28 13:26:36 +0100220 goto exit;
221 }
Paul Bakker5121ce52009-01-03 21:22:43 +0000222
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200223 if( ( ret = mbedtls_rsa_pkcs1_verify( &rsa, NULL, NULL, MBEDTLS_RSA_PUBLIC,
224 MBEDTLS_MD_SHA256, 0, hash, p ) ) != 0 )
Paul Bakker5121ce52009-01-03 21:22:43 +0000225 {
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200226 mbedtls_printf( " failed\n ! mbedtls_rsa_pkcs1_verify returned %d\n\n", ret );
Paul Bakker5121ce52009-01-03 21:22:43 +0000227 goto exit;
228 }
229
230 /*
231 * 6. Send our public value: Yc = G ^ Xc mod P
232 */
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200233 mbedtls_printf( "\n . Sending own public value to server" );
Paul Bakker5121ce52009-01-03 21:22:43 +0000234 fflush( stdout );
235
236 n = dhm.len;
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200237 if( ( ret = mbedtls_dhm_make_public( &dhm, (int) dhm.len, buf, n,
238 mbedtls_ctr_drbg_random, &ctr_drbg ) ) != 0 )
Paul Bakker5121ce52009-01-03 21:22:43 +0000239 {
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200240 mbedtls_printf( " failed\n ! mbedtls_dhm_make_public returned %d\n\n", ret );
Paul Bakker5121ce52009-01-03 21:22:43 +0000241 goto exit;
242 }
243
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200244 if( ( ret = mbedtls_net_send( &server_fd, buf, n ) ) != (int) n )
Paul Bakker5121ce52009-01-03 21:22:43 +0000245 {
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200246 mbedtls_printf( " failed\n ! mbedtls_net_send returned %d\n\n", ret );
Paul Bakker5121ce52009-01-03 21:22:43 +0000247 goto exit;
248 }
249
250 /*
251 * 7. Derive the shared secret: K = Ys ^ Xc mod P
252 */
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200253 mbedtls_printf( "\n . Shared secret: " );
Paul Bakker5121ce52009-01-03 21:22:43 +0000254 fflush( stdout );
255
Manuel Pégourié-Gonnard33352052015-06-02 16:17:08 +0100256 if( ( ret = mbedtls_dhm_calc_secret( &dhm, buf, sizeof( buf ), &n,
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200257 mbedtls_ctr_drbg_random, &ctr_drbg ) ) != 0 )
Paul Bakker5121ce52009-01-03 21:22:43 +0000258 {
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200259 mbedtls_printf( " failed\n ! mbedtls_dhm_calc_secret returned %d\n\n", ret );
Paul Bakker5121ce52009-01-03 21:22:43 +0000260 goto exit;
261 }
262
263 for( n = 0; n < 16; n++ )
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200264 mbedtls_printf( "%02x", buf[n] );
Paul Bakker5121ce52009-01-03 21:22:43 +0000265
266 /*
267 * 8. Setup the AES-256 decryption key
268 *
269 * This is an overly simplified example; best practice is
270 * to hash the shared secret with a random value to derive
271 * the keying material for the encryption/decryption keys,
272 * IVs and MACs.
273 */
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200274 mbedtls_printf( "...\n . Receiving and decrypting the ciphertext" );
Paul Bakker5121ce52009-01-03 21:22:43 +0000275 fflush( stdout );
276
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200277 mbedtls_aes_setkey_dec( &aes, buf, 256 );
Paul Bakker5121ce52009-01-03 21:22:43 +0000278
279 memset( buf, 0, sizeof( buf ) );
280
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200281 if( ( ret = mbedtls_net_recv( &server_fd, buf, 16 ) ) != 16 )
Paul Bakker5121ce52009-01-03 21:22:43 +0000282 {
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200283 mbedtls_printf( " failed\n ! mbedtls_net_recv returned %d\n\n", ret );
Paul Bakker5121ce52009-01-03 21:22:43 +0000284 goto exit;
285 }
286
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200287 mbedtls_aes_crypt_ecb( &aes, MBEDTLS_AES_DECRYPT, buf, buf );
Paul Bakker5121ce52009-01-03 21:22:43 +0000288 buf[16] = '\0';
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200289 mbedtls_printf( "\n . Plaintext is \"%s\"\n\n", (char *) buf );
Paul Bakker5121ce52009-01-03 21:22:43 +0000290
Andres Amaya Garcia898841d2018-04-29 19:23:39 +0100291 exit_code = MBEDTLS_EXIT_SUCCESS;
292
Paul Bakker5121ce52009-01-03 21:22:43 +0000293exit:
294
Manuel Pégourié-Gonnard3d7d00a2015-06-30 15:55:03 +0200295 mbedtls_net_free( &server_fd );
Paul Bakker0c226102014-04-17 16:02:36 +0200296
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200297 mbedtls_aes_free( &aes );
298 mbedtls_rsa_free( &rsa );
299 mbedtls_dhm_free( &dhm );
300 mbedtls_ctr_drbg_free( &ctr_drbg );
301 mbedtls_entropy_free( &entropy );
Paul Bakker5121ce52009-01-03 21:22:43 +0000302
Paul Bakkercce9d772011-11-18 14:26:47 +0000303#if defined(_WIN32)
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200304 mbedtls_printf( " + Press Enter to exit this program.\n" );
Paul Bakker5121ce52009-01-03 21:22:43 +0000305 fflush( stdout ); getchar();
306#endif
307
Krzysztof Stachowiak5e1b1952019-04-24 14:24:46 +0200308 mbedtls_exit( exit_code );
Paul Bakker5121ce52009-01-03 21:22:43 +0000309}
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200310#endif /* MBEDTLS_AES_C && MBEDTLS_DHM_C && MBEDTLS_ENTROPY_C &&
311 MBEDTLS_NET_C && MBEDTLS_RSA_C && MBEDTLS_SHA256_C &&
312 MBEDTLS_FS_IO && MBEDTLS_CTR_DRBG_C */