1 /*
2 * Copyright 2013-2024 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 /*
11 * Simple AES CCM authenticated encryption with additional data (AEAD)
12 * demonstration program.
13 */
14
15 #include <stdio.h>
16 #include <openssl/err.h>
17 #include <openssl/bio.h>
18 #include <openssl/evp.h>
19 #include <openssl/core_names.h>
20
21 /* AES-CCM test data obtained from NIST public test vectors */
22
23 /* AES key */
24 static const unsigned char ccm_key[] = {
25 0xce, 0xb0, 0x09, 0xae, 0xa4, 0x45, 0x44, 0x51, 0xfe, 0xad, 0xf0, 0xe6,
26 0xb3, 0x6f, 0x45, 0x55, 0x5d, 0xd0, 0x47, 0x23, 0xba, 0xa4, 0x48, 0xe8
27 };
28
29 /* Unique nonce to be used for this message */
30 static const unsigned char ccm_nonce[] = {
31 0x76, 0x40, 0x43, 0xc4, 0x94, 0x60, 0xb7
32 };
33
34 /*
35 * Example of Additional Authenticated Data (AAD), i.e. unencrypted data
36 * which can be authenticated using the generated Tag value.
37 */
38 static const unsigned char ccm_adata[] = {
39 0x6e, 0x80, 0xdd, 0x7f, 0x1b, 0xad, 0xf3, 0xa1, 0xc9, 0xab, 0x25, 0xc7,
40 0x5f, 0x10, 0xbd, 0xe7, 0x8c, 0x23, 0xfa, 0x0e, 0xb8, 0xf9, 0xaa, 0xa5,
41 0x3a, 0xde, 0xfb, 0xf4, 0xcb, 0xf7, 0x8f, 0xe4
42 };
43
44 /* Example plaintext to encrypt */
45 static const unsigned char ccm_pt[] = {
46 0xc8, 0xd2, 0x75, 0xf9, 0x19, 0xe1, 0x7d, 0x7f, 0xe6, 0x9c, 0x2a, 0x1f,
47 0x58, 0x93, 0x9d, 0xfe, 0x4d, 0x40, 0x37, 0x91, 0xb5, 0xdf, 0x13, 0x10
48 };
49
50 /* Expected ciphertext value */
51 static const unsigned char ccm_ct[] = {
52 0x8a, 0x0f, 0x3d, 0x82, 0x29, 0xe4, 0x8e, 0x74, 0x87, 0xfd, 0x95, 0xa2,
53 0x8a, 0xd3, 0x92, 0xc8, 0x0b, 0x36, 0x81, 0xd4, 0xfb, 0xc7, 0xbb, 0xfd
54 };
55
56 /* Expected AEAD Tag value */
57 static const unsigned char ccm_tag[] = {
58 0x2d, 0xd6, 0xef, 0x1c, 0x45, 0xd4, 0xcc, 0xb7, 0x23, 0xdc, 0x07, 0x44,
59 0x14, 0xdb, 0x50, 0x6d
60 };
61
62 /*
63 * A library context and property query can be used to select & filter
64 * algorithm implementations. If they are NULL then the default library
65 * context and properties are used.
66 */
67 static OSSL_LIB_CTX *libctx = NULL;
68 static const char *propq = NULL;
69
aes_ccm_encrypt(void)70 static int aes_ccm_encrypt(void)
71 {
72 int ret = 0;
73 EVP_CIPHER_CTX *ctx;
74 EVP_CIPHER *cipher = NULL;
75 int outlen, tmplen;
76 size_t ccm_nonce_len = sizeof(ccm_nonce);
77 size_t ccm_tag_len = sizeof(ccm_tag);
78 unsigned char outbuf[1024];
79 unsigned char outtag[16];
80 OSSL_PARAM params[3] = {
81 OSSL_PARAM_END, OSSL_PARAM_END, OSSL_PARAM_END
82 };
83
84 printf("AES CCM Encrypt:\n");
85 printf("Plaintext:\n");
86 BIO_dump_fp(stdout, ccm_pt, sizeof(ccm_pt));
87
88 /* Create a context for the encrypt operation */
89 if ((ctx = EVP_CIPHER_CTX_new()) == NULL)
90 goto err;
91
92 /* Fetch the cipher implementation */
93 if ((cipher = EVP_CIPHER_fetch(libctx, "AES-192-CCM", propq)) == NULL)
94 goto err;
95
96 /* Default nonce length for AES-CCM is 7 bytes (56 bits). */
97 params[0] = OSSL_PARAM_construct_size_t(OSSL_CIPHER_PARAM_AEAD_IVLEN,
98 &ccm_nonce_len);
99 /* Set tag length */
100 params[1] = OSSL_PARAM_construct_octet_string(OSSL_CIPHER_PARAM_AEAD_TAG,
101 NULL, ccm_tag_len);
102
103 /*
104 * Initialise encrypt operation with the cipher & mode,
105 * nonce length and tag length parameters.
106 */
107 if (!EVP_EncryptInit_ex2(ctx, cipher, NULL, NULL, params))
108 goto err;
109
110 /* Initialise key and nonce */
111 if (!EVP_EncryptInit_ex(ctx, NULL, NULL, ccm_key, ccm_nonce))
112 goto err;
113
114 /* Set plaintext length: only needed if AAD is used */
115 if (!EVP_EncryptUpdate(ctx, NULL, &outlen, NULL, sizeof(ccm_pt)))
116 goto err;
117
118 /* Zero or one call to specify any AAD */
119 if (!EVP_EncryptUpdate(ctx, NULL, &outlen, ccm_adata, sizeof(ccm_adata)))
120 goto err;
121
122 /* Encrypt plaintext: can only be called once */
123 if (!EVP_EncryptUpdate(ctx, outbuf, &outlen, ccm_pt, sizeof(ccm_pt)))
124 goto err;
125
126 /* Output encrypted block */
127 printf("Ciphertext:\n");
128 BIO_dump_fp(stdout, outbuf, outlen);
129
130 /* Finalise: note get no output for CCM */
131 if (!EVP_EncryptFinal_ex(ctx, NULL, &tmplen))
132 goto err;
133
134 /* Get tag */
135 params[0] = OSSL_PARAM_construct_octet_string(OSSL_CIPHER_PARAM_AEAD_TAG,
136 outtag, ccm_tag_len);
137 params[1] = OSSL_PARAM_construct_end();
138
139 if (!EVP_CIPHER_CTX_get_params(ctx, params))
140 goto err;
141
142 /* Output tag */
143 printf("Tag:\n");
144 BIO_dump_fp(stdout, outtag, ccm_tag_len);
145
146 ret = 1;
147 err:
148 if (!ret)
149 ERR_print_errors_fp(stderr);
150
151 EVP_CIPHER_free(cipher);
152 EVP_CIPHER_CTX_free(ctx);
153
154 return ret;
155 }
156
aes_ccm_decrypt(void)157 static int aes_ccm_decrypt(void)
158 {
159 int ret = 0;
160 EVP_CIPHER_CTX *ctx;
161 EVP_CIPHER *cipher = NULL;
162 int outlen, rv;
163 unsigned char outbuf[1024];
164 size_t ccm_nonce_len = sizeof(ccm_nonce);
165 OSSL_PARAM params[3] = {
166 OSSL_PARAM_END, OSSL_PARAM_END, OSSL_PARAM_END
167 };
168
169 printf("AES CCM Decrypt:\n");
170 printf("Ciphertext:\n");
171 BIO_dump_fp(stdout, ccm_ct, sizeof(ccm_ct));
172
173 if ((ctx = EVP_CIPHER_CTX_new()) == NULL)
174 goto err;
175
176 /* Fetch the cipher implementation */
177 if ((cipher = EVP_CIPHER_fetch(libctx, "AES-192-CCM", propq)) == NULL)
178 goto err;
179
180 /* Set nonce length if default 96 bits is not appropriate */
181 params[0] = OSSL_PARAM_construct_size_t(OSSL_CIPHER_PARAM_AEAD_IVLEN,
182 &ccm_nonce_len);
183 /* Set tag length */
184 params[1] = OSSL_PARAM_construct_octet_string(OSSL_CIPHER_PARAM_AEAD_TAG,
185 (unsigned char *)ccm_tag,
186 sizeof(ccm_tag));
187 /*
188 * Initialise decrypt operation with the cipher & mode,
189 * nonce length and expected tag parameters.
190 */
191 if (!EVP_DecryptInit_ex2(ctx, cipher, NULL, NULL, params))
192 goto err;
193
194 /* Specify key and IV */
195 if (!EVP_DecryptInit_ex(ctx, NULL, NULL, ccm_key, ccm_nonce))
196 goto err;
197
198 /* Set ciphertext length: only needed if we have AAD */
199 if (!EVP_DecryptUpdate(ctx, NULL, &outlen, NULL, sizeof(ccm_ct)))
200 goto err;
201
202 /* Zero or one call to specify any AAD */
203 if (!EVP_DecryptUpdate(ctx, NULL, &outlen, ccm_adata, sizeof(ccm_adata)))
204 goto err;
205
206 /* Decrypt plaintext, verify tag: can only be called once */
207 rv = EVP_DecryptUpdate(ctx, outbuf, &outlen, ccm_ct, sizeof(ccm_ct));
208
209 /* Output decrypted block: if tag verify failed we get nothing */
210 if (rv > 0) {
211 printf("Tag verify successful!\nPlaintext:\n");
212 BIO_dump_fp(stdout, outbuf, outlen);
213 } else {
214 printf("Tag verify failed!\nPlaintext not available\n");
215 goto err;
216 }
217 ret = 1;
218 err:
219 if (!ret)
220 ERR_print_errors_fp(stderr);
221
222 EVP_CIPHER_free(cipher);
223 EVP_CIPHER_CTX_free(ctx);
224
225 return ret;
226 }
227
main(int argc,char ** argv)228 int main(int argc, char **argv)
229 {
230 if (!aes_ccm_encrypt())
231 return EXIT_FAILURE;
232
233 if (!aes_ccm_decrypt())
234 return EXIT_FAILURE;
235
236 return EXIT_SUCCESS;
237 }
238