1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
|
/*-
* Copyright 2021 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the Apache License 2.0 (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
/*
* An example that uses EVP_PKEY_encrypt and EVP_PKEY_decrypt methods
* to encrypt and decrypt data using an RSA keypair.
* RSA encryption produces different encrypted output each time it is run,
* hence this is not a known answer test.
*/
#include <stdio.h>
#include <stdlib.h>
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/decoder.h>
#include <openssl/core_names.h>
#include "rsa_encrypt.h"
/* Input data to encrypt */
static const unsigned char msg[] =
"To be, or not to be, that is the question,\n"
"Whether tis nobler in the minde to suffer\n"
"The slings and arrowes of outragious fortune,\n"
"Or to take Armes again in a sea of troubles";
/*
* For do_encrypt(), load an RSA public key from pub_key_der[].
* For do_decrypt(), load an RSA private key from priv_key_der[].
*/
static EVP_PKEY *get_key(OSSL_LIB_CTX *libctx, const char *propq, int public)
{
OSSL_DECODER_CTX *dctx = NULL;
EVP_PKEY *pkey = NULL;
int selection;
const unsigned char *data;
size_t data_len;
if (public) {
selection = EVP_PKEY_PUBLIC_KEY;
data = pub_key_der;
data_len = sizeof(pub_key_der);
} else {
selection = EVP_PKEY_KEYPAIR;
data = priv_key_der;
data_len = sizeof(priv_key_der);
}
dctx = OSSL_DECODER_CTX_new_for_pkey(&pkey, "DER", NULL, "RSA",
selection, libctx, propq);
(void)OSSL_DECODER_from_data(dctx, &data, &data_len);
OSSL_DECODER_CTX_free(dctx);
return pkey;
}
/* Set optional parameters for RSA OAEP Padding */
static void set_optional_params(OSSL_PARAM *p, const char *propq)
{
static unsigned char label[] = "label";
/* "pkcs1" is used by default if the padding mode is not set */
*p++ = OSSL_PARAM_construct_utf8_string(OSSL_ASYM_CIPHER_PARAM_PAD_MODE,
OSSL_PKEY_RSA_PAD_MODE_OAEP, 0);
/* No oaep_label is used if this is not set */
*p++ = OSSL_PARAM_construct_octet_string(OSSL_ASYM_CIPHER_PARAM_OAEP_LABEL,
label, sizeof(label));
/* "SHA1" is used if this is not set */
*p++ = OSSL_PARAM_construct_utf8_string(OSSL_ASYM_CIPHER_PARAM_OAEP_DIGEST,
"SHA256", 0);
/*
* If a non default property query needs to be specified when fetching the
* OAEP digest then it needs to be specified here.
*/
if (propq != NULL)
*p++ = OSSL_PARAM_construct_utf8_string(OSSL_ASYM_CIPHER_PARAM_OAEP_DIGEST_PROPS,
(char *)propq, 0);
/*
* OSSL_ASYM_CIPHER_PARAM_MGF1_DIGEST and
* OSSL_ASYM_CIPHER_PARAM_MGF1_DIGEST_PROPS can also be optionally added
* here if the MGF1 digest differs from the OAEP digest.
*/
*p = OSSL_PARAM_construct_end();
}
/*
* The length of the input data that can be encrypted is limited by the
* RSA key length minus some additional bytes that depends on the padding mode.
*
*/
static int do_encrypt(OSSL_LIB_CTX *libctx,
const unsigned char *in, size_t in_len,
unsigned char **out, size_t *out_len)
{
int ret = 0, public = 1;
size_t buf_len = 0;
unsigned char *buf = NULL;
const char *propq = NULL;
EVP_PKEY_CTX *ctx = NULL;
EVP_PKEY *pub_key = NULL;
OSSL_PARAM params[5];
/* Get public key */
pub_key = get_key(libctx, propq, public);
if (pub_key == NULL) {
fprintf(stderr, "Get public key failed.\n");
goto cleanup;
}
ctx = EVP_PKEY_CTX_new_from_pkey(libctx, pub_key, propq);
if (ctx == NULL) {
fprintf(stderr, "EVP_PKEY_CTX_new_from_pkey() failed.\n");
goto cleanup;
}
set_optional_params(params, propq);
/* If no optional parameters are required then NULL can be passed */
if (EVP_PKEY_encrypt_init_ex(ctx, params) <= 0) {
fprintf(stderr, "EVP_PKEY_encrypt_init_ex() failed.\n");
goto cleanup;
}
/* Calculate the size required to hold the encrypted data */
if (EVP_PKEY_encrypt(ctx, NULL, &buf_len, in, in_len) <= 0) {
fprintf(stderr, "EVP_PKEY_encrypt() failed.\n");
goto cleanup;
}
buf = OPENSSL_zalloc(buf_len);
if (buf == NULL) {
fprintf(stderr, "Malloc failed.\n");
goto cleanup;
}
if (EVP_PKEY_encrypt(ctx, buf, &buf_len, in, in_len) <= 0) {
fprintf(stderr, "EVP_PKEY_encrypt() failed.\n");
goto cleanup;
}
*out_len = buf_len;
*out = buf;
fprintf(stdout, "Encrypted:\n");
BIO_dump_indent_fp(stdout, buf, buf_len, 2);
fprintf(stdout, "\n");
ret = 1;
cleanup:
if (!ret)
OPENSSL_free(buf);
EVP_PKEY_free(pub_key);
EVP_PKEY_CTX_free(ctx);
return ret;
}
static int do_decrypt(OSSL_LIB_CTX *libctx, const unsigned char *in, size_t in_len,
unsigned char **out, size_t *out_len)
{
int ret = 0, public = 0;
size_t buf_len = 0;
unsigned char *buf = NULL;
const char *propq = NULL;
EVP_PKEY_CTX *ctx = NULL;
EVP_PKEY *priv_key = NULL;
OSSL_PARAM params[5];
/* Get private key */
priv_key = get_key(libctx, propq, public);
if (priv_key == NULL) {
fprintf(stderr, "Get private key failed.\n");
goto cleanup;
}
ctx = EVP_PKEY_CTX_new_from_pkey(libctx, priv_key, propq);
if (ctx == NULL) {
fprintf(stderr, "EVP_PKEY_CTX_new_from_pkey() failed.\n");
goto cleanup;
}
/* The parameters used for encryption must also be used for decryption */
set_optional_params(params, propq);
/* If no optional parameters are required then NULL can be passed */
if (EVP_PKEY_decrypt_init_ex(ctx, params) <= 0) {
fprintf(stderr, "EVP_PKEY_decrypt_init_ex() failed.\n");
goto cleanup;
}
/* Calculate the size required to hold the decrypted data */
if (EVP_PKEY_decrypt(ctx, NULL, &buf_len, in, in_len) <= 0) {
fprintf(stderr, "EVP_PKEY_decrypt() failed.\n");
goto cleanup;
}
buf = OPENSSL_zalloc(buf_len);
if (buf == NULL) {
fprintf(stderr, "Malloc failed.\n");
goto cleanup;
}
if (EVP_PKEY_decrypt(ctx, buf, &buf_len, in, in_len) <= 0) {
fprintf(stderr, "EVP_PKEY_decrypt() failed.\n");
goto cleanup;
}
*out_len = buf_len;
*out = buf;
fprintf(stdout, "Decrypted:\n");
BIO_dump_indent_fp(stdout, buf, buf_len, 2);
fprintf(stdout, "\n");
ret = 1;
cleanup:
if (!ret)
OPENSSL_free(buf);
EVP_PKEY_free(priv_key);
EVP_PKEY_CTX_free(ctx);
return ret;
}
int main(void)
{
int ret = EXIT_FAILURE;
size_t msg_len = sizeof(msg) - 1;
size_t encrypted_len = 0, decrypted_len = 0;
unsigned char *encrypted = NULL, *decrypted = NULL;
OSSL_LIB_CTX *libctx = NULL;
if (!do_encrypt(libctx, msg, msg_len, &encrypted, &encrypted_len)) {
fprintf(stderr, "encryption failed.\n");
goto cleanup;
}
if (!do_decrypt(libctx, encrypted, encrypted_len,
&decrypted, &decrypted_len)) {
fprintf(stderr, "decryption failed.\n");
goto cleanup;
}
if (CRYPTO_memcmp(msg, decrypted, decrypted_len) != 0) {
fprintf(stderr, "Decrypted data does not match expected value\n");
goto cleanup;
}
ret = EXIT_SUCCESS;
cleanup:
OPENSSL_free(decrypted);
OPENSSL_free(encrypted);
OSSL_LIB_CTX_free(libctx);
if (ret != EXIT_SUCCESS)
ERR_print_errors_fp(stderr);
return ret;
}
|