1 /*
2 * Example ECDSA program
3 *
4 * Copyright The Mbed TLS Contributors
5 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
6 */
7
8 #if !defined(MBEDTLS_CONFIG_FILE)
9 #include "mbedtls/config.h"
10 #else
11 #include MBEDTLS_CONFIG_FILE
12 #endif
13
14 #include "mbedtls/platform.h"
15
16 #if defined(MBEDTLS_ECDSA_C) && \
17 defined(MBEDTLS_ENTROPY_C) && defined(MBEDTLS_CTR_DRBG_C)
18 #include "mbedtls/entropy.h"
19 #include "mbedtls/ctr_drbg.h"
20 #include "mbedtls/ecdsa.h"
21 #include "mbedtls/sha256.h"
22
23 #include <string.h>
24 #endif
25
26 /*
27 * Uncomment to show key and signature details
28 */
29 #define VERBOSE
30
31 /*
32 * Uncomment to force use of a specific curve
33 */
34 #define ECPARAMS MBEDTLS_ECP_DP_SECP192R1
35
36 #if !defined(ECPARAMS)
37 #define ECPARAMS mbedtls_ecp_curve_list()->grp_id
38 #endif
39
40 #if !defined(MBEDTLS_ECDSA_C) || !defined(MBEDTLS_SHA256_C) || \
41 !defined(MBEDTLS_ENTROPY_C) || !defined(MBEDTLS_CTR_DRBG_C)
main(void)42 int main(void)
43 {
44 mbedtls_printf("MBEDTLS_ECDSA_C and/or MBEDTLS_SHA256_C and/or "
45 "MBEDTLS_ENTROPY_C and/or MBEDTLS_CTR_DRBG_C not defined\n");
46 mbedtls_exit(0);
47 }
48 #else
49 #if defined(VERBOSE)
dump_buf(const char * title,unsigned char * buf,size_t len)50 static void dump_buf(const char *title, unsigned char *buf, size_t len)
51 {
52 size_t i;
53
54 mbedtls_printf("%s", title);
55 for (i = 0; i < len; i++) {
56 mbedtls_printf("%c%c", "0123456789ABCDEF" [buf[i] / 16],
57 "0123456789ABCDEF" [buf[i] % 16]);
58 }
59 mbedtls_printf("\n");
60 }
61
dump_pubkey(const char * title,mbedtls_ecdsa_context * key)62 static void dump_pubkey(const char *title, mbedtls_ecdsa_context *key)
63 {
64 unsigned char buf[300];
65 size_t len;
66
67 if (mbedtls_ecp_point_write_binary(&key->grp, &key->Q,
68 MBEDTLS_ECP_PF_UNCOMPRESSED, &len, buf, sizeof(buf)) != 0) {
69 mbedtls_printf("internal error\n");
70 return;
71 }
72
73 dump_buf(title, buf, len);
74 }
75 #else
76 #define dump_buf(a, b, c)
77 #define dump_pubkey(a, b)
78 #endif
79
80
main(int argc,char * argv[])81 int main(int argc, char *argv[])
82 {
83 int ret = 1;
84 int exit_code = MBEDTLS_EXIT_FAILURE;
85 mbedtls_ecdsa_context ctx_sign, ctx_verify;
86 mbedtls_entropy_context entropy;
87 mbedtls_ctr_drbg_context ctr_drbg;
88 unsigned char message[100];
89 unsigned char hash[32];
90 unsigned char sig[MBEDTLS_ECDSA_MAX_LEN];
91 size_t sig_len;
92 const char *pers = "ecdsa";
93 ((void) argv);
94
95 mbedtls_ecdsa_init(&ctx_sign);
96 mbedtls_ecdsa_init(&ctx_verify);
97 mbedtls_ctr_drbg_init(&ctr_drbg);
98
99 memset(sig, 0, sizeof(sig));
100 memset(message, 0x25, sizeof(message));
101
102 if (argc != 1) {
103 mbedtls_printf("usage: ecdsa\n");
104
105 #if defined(_WIN32)
106 mbedtls_printf("\n");
107 #endif
108
109 goto exit;
110 }
111
112 /*
113 * Generate a key pair for signing
114 */
115 mbedtls_printf("\n . Seeding the random number generator...");
116 fflush(stdout);
117
118 mbedtls_entropy_init(&entropy);
119 if ((ret = mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func, &entropy,
120 (const unsigned char *) pers,
121 strlen(pers))) != 0) {
122 mbedtls_printf(" failed\n ! mbedtls_ctr_drbg_seed returned %d\n", ret);
123 goto exit;
124 }
125
126 mbedtls_printf(" ok\n . Generating key pair...");
127 fflush(stdout);
128
129 if ((ret = mbedtls_ecdsa_genkey(&ctx_sign, ECPARAMS,
130 mbedtls_ctr_drbg_random, &ctr_drbg)) != 0) {
131 mbedtls_printf(" failed\n ! mbedtls_ecdsa_genkey returned %d\n", ret);
132 goto exit;
133 }
134
135 mbedtls_printf(" ok (key size: %d bits)\n", (int) ctx_sign.grp.pbits);
136
137 dump_pubkey(" + Public key: ", &ctx_sign);
138
139 /*
140 * Compute message hash
141 */
142 mbedtls_printf(" . Computing message hash...");
143 fflush(stdout);
144
145 if ((ret = mbedtls_sha256_ret(message, sizeof(message), hash, 0)) != 0) {
146 mbedtls_printf(" failed\n ! mbedtls_sha256_ret returned %d\n", ret);
147 goto exit;
148 }
149
150 mbedtls_printf(" ok\n");
151
152 dump_buf(" + Hash: ", hash, sizeof(hash));
153
154 /*
155 * Sign message hash
156 */
157 mbedtls_printf(" . Signing message hash...");
158 fflush(stdout);
159
160 if ((ret = mbedtls_ecdsa_write_signature(&ctx_sign, MBEDTLS_MD_SHA256,
161 hash, sizeof(hash),
162 sig, &sig_len,
163 mbedtls_ctr_drbg_random, &ctr_drbg)) != 0) {
164 mbedtls_printf(" failed\n ! mbedtls_ecdsa_write_signature returned %d\n", ret);
165 goto exit;
166 }
167 mbedtls_printf(" ok (signature length = %u)\n", (unsigned int) sig_len);
168
169 dump_buf(" + Signature: ", sig, sig_len);
170
171 /*
172 * Transfer public information to verifying context
173 *
174 * We could use the same context for verification and signatures, but we
175 * chose to use a new one in order to make it clear that the verifying
176 * context only needs the public key (Q), and not the private key (d).
177 */
178 mbedtls_printf(" . Preparing verification context...");
179 fflush(stdout);
180
181 if ((ret = mbedtls_ecp_group_copy(&ctx_verify.grp, &ctx_sign.grp)) != 0) {
182 mbedtls_printf(" failed\n ! mbedtls_ecp_group_copy returned %d\n", ret);
183 goto exit;
184 }
185
186 if ((ret = mbedtls_ecp_copy(&ctx_verify.Q, &ctx_sign.Q)) != 0) {
187 mbedtls_printf(" failed\n ! mbedtls_ecp_copy returned %d\n", ret);
188 goto exit;
189 }
190
191 /*
192 * Verify signature
193 */
194 mbedtls_printf(" ok\n . Verifying signature...");
195 fflush(stdout);
196
197 if ((ret = mbedtls_ecdsa_read_signature(&ctx_verify,
198 hash, sizeof(hash),
199 sig, sig_len)) != 0) {
200 mbedtls_printf(" failed\n ! mbedtls_ecdsa_read_signature returned %d\n", ret);
201 goto exit;
202 }
203
204 mbedtls_printf(" ok\n");
205
206 exit_code = MBEDTLS_EXIT_SUCCESS;
207
208 exit:
209
210 #if defined(_WIN32)
211 mbedtls_printf(" + Press Enter to exit this program.\n");
212 fflush(stdout); getchar();
213 #endif
214
215 mbedtls_ecdsa_free(&ctx_verify);
216 mbedtls_ecdsa_free(&ctx_sign);
217 mbedtls_ctr_drbg_free(&ctr_drbg);
218 mbedtls_entropy_free(&entropy);
219
220 mbedtls_exit(exit_code);
221 }
222 #endif /* MBEDTLS_ECDSA_C && MBEDTLS_ENTROPY_C && MBEDTLS_CTR_DRBG_C &&
223 ECPARAMS */
224