1 /*
2 * Copyright 2022-2023 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10 #include <stdio.h>
11 #include <stdlib.h>
12 #include <openssl/core_names.h>
13 #include <openssl/evp.h>
14 #include <openssl/rsa.h>
15 #include <openssl/params.h>
16 #include <openssl/err.h>
17 #include <openssl/bio.h>
18 #include "rsa_pss.h"
19
20 /* The data to be signed. This will be hashed. */
21 static const char test_message[] =
22 "This is an example message to be signed.";
23
24 /* A property query used for selecting algorithm implementations. */
25 static const char *propq = NULL;
26
27 /*
28 * This function demonstrates RSA signing of an arbitrary-length message.
29 * Hashing is performed automatically. In this example, SHA-256 is used. If you
30 * have already hashed your message and simply want to sign the hash directly,
31 * see rsa_pss_direct.c.
32 */
sign(OSSL_LIB_CTX * libctx,unsigned char ** sig,size_t * sig_len)33 static int sign(OSSL_LIB_CTX *libctx, unsigned char **sig, size_t *sig_len)
34 {
35 int ret = 0;
36 EVP_PKEY *pkey = NULL;
37 EVP_MD_CTX *mctx = NULL;
38 OSSL_PARAM params[2], *p = params;
39 const unsigned char *ppriv_key = NULL;
40
41 *sig = NULL;
42
43 /* Load DER-encoded RSA private key. */
44 ppriv_key = rsa_priv_key;
45 pkey = d2i_PrivateKey_ex(EVP_PKEY_RSA, NULL, &ppriv_key,
46 sizeof(rsa_priv_key), libctx, propq);
47 if (pkey == NULL) {
48 fprintf(stderr, "Failed to load private key\n");
49 goto end;
50 }
51
52 /* Create MD context used for signing. */
53 mctx = EVP_MD_CTX_new();
54 if (mctx == NULL) {
55 fprintf(stderr, "Failed to create MD context\n");
56 goto end;
57 }
58
59 /* Initialize MD context for signing. */
60 *p++ = OSSL_PARAM_construct_utf8_string(OSSL_SIGNATURE_PARAM_PAD_MODE,
61 OSSL_PKEY_RSA_PAD_MODE_PSS, 0);
62 *p = OSSL_PARAM_construct_end();
63
64 if (EVP_DigestSignInit_ex(mctx, NULL, "SHA256", libctx, propq,
65 pkey, params) == 0) {
66 fprintf(stderr, "Failed to initialize signing context\n");
67 goto end;
68 }
69
70 /*
71 * Feed data to be signed into the algorithm. This may
72 * be called multiple times.
73 */
74 if (EVP_DigestSignUpdate(mctx, test_message, sizeof(test_message)) == 0) {
75 fprintf(stderr, "Failed to hash message into signing context\n");
76 goto end;
77 }
78
79 /* Determine signature length. */
80 if (EVP_DigestSignFinal(mctx, NULL, sig_len) == 0) {
81 fprintf(stderr, "Failed to get signature length\n");
82 goto end;
83 }
84
85 /* Allocate memory for signature. */
86 *sig = OPENSSL_malloc(*sig_len);
87 if (*sig == NULL) {
88 fprintf(stderr, "Failed to allocate memory for signature\n");
89 goto end;
90 }
91
92 /* Generate signature. */
93 if (EVP_DigestSignFinal(mctx, *sig, sig_len) == 0) {
94 fprintf(stderr, "Failed to sign\n");
95 goto end;
96 }
97
98 ret = 1;
99 end:
100 EVP_MD_CTX_free(mctx);
101 EVP_PKEY_free(pkey);
102
103 if (ret == 0)
104 OPENSSL_free(*sig);
105
106 return ret;
107 }
108
109 /*
110 * This function demonstrates verification of an RSA signature over an
111 * arbitrary-length message using the PSS signature scheme. Hashing is performed
112 * automatically.
113 */
verify(OSSL_LIB_CTX * libctx,const unsigned char * sig,size_t sig_len)114 static int verify(OSSL_LIB_CTX *libctx, const unsigned char *sig, size_t sig_len)
115 {
116 int ret = 0;
117 EVP_PKEY *pkey = NULL;
118 EVP_MD_CTX *mctx = NULL;
119 OSSL_PARAM params[2], *p = params;
120 const unsigned char *ppub_key = NULL;
121
122 /* Load DER-encoded RSA public key. */
123 ppub_key = rsa_pub_key;
124 pkey = d2i_PublicKey(EVP_PKEY_RSA, NULL, &ppub_key, sizeof(rsa_pub_key));
125 if (pkey == NULL) {
126 fprintf(stderr, "Failed to load public key\n");
127 goto end;
128 }
129
130 /* Create MD context used for verification. */
131 mctx = EVP_MD_CTX_new();
132 if (mctx == NULL) {
133 fprintf(stderr, "Failed to create MD context\n");
134 goto end;
135 }
136
137 /* Initialize MD context for verification. */
138 *p++ = OSSL_PARAM_construct_utf8_string(OSSL_SIGNATURE_PARAM_PAD_MODE,
139 OSSL_PKEY_RSA_PAD_MODE_PSS, 0);
140 *p = OSSL_PARAM_construct_end();
141
142 if (EVP_DigestVerifyInit_ex(mctx, NULL, "SHA256", libctx, propq,
143 pkey, params) == 0) {
144 fprintf(stderr, "Failed to initialize signing context\n");
145 goto end;
146 }
147
148 /*
149 * Feed data to be signed into the algorithm. This may
150 * be called multiple times.
151 */
152 if (EVP_DigestVerifyUpdate(mctx, test_message, sizeof(test_message)) == 0) {
153 fprintf(stderr, "Failed to hash message into signing context\n");
154 goto end;
155 }
156
157 /* Verify signature. */
158 if (EVP_DigestVerifyFinal(mctx, sig, sig_len) == 0) {
159 fprintf(stderr, "Failed to verify signature; "
160 "signature may be invalid\n");
161 goto end;
162 }
163
164 ret = 1;
165 end:
166 EVP_MD_CTX_free(mctx);
167 EVP_PKEY_free(pkey);
168 return ret;
169 }
170
main(int argc,char ** argv)171 int main(int argc, char **argv)
172 {
173 int ret = EXIT_FAILURE;
174 OSSL_LIB_CTX *libctx = NULL;
175 unsigned char *sig = NULL;
176 size_t sig_len = 0;
177
178 if (sign(libctx, &sig, &sig_len) == 0)
179 goto end;
180
181 if (verify(libctx, sig, sig_len) == 0)
182 goto end;
183
184 printf("Success\n");
185
186 ret = EXIT_SUCCESS;
187 end:
188 OPENSSL_free(sig);
189 OSSL_LIB_CTX_free(libctx);
190 return ret;
191 }
192
