1/*
2 * Copyright 2013-2021 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 */
24static 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 */
30static 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 */
38static 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 */
45static 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 */
51static 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 */
57static 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 */
67OSSL_LIB_CTX *libctx = NULL;
68const char *propq = NULL;
69
70
71int aes_ccm_encrypt(void)
72{
73    int ret = 0;
74    EVP_CIPHER_CTX *ctx;
75    EVP_CIPHER *cipher = NULL;
76    int outlen, tmplen;
77    size_t ccm_nonce_len = sizeof(ccm_nonce);
78    size_t ccm_tag_len = sizeof(ccm_tag);
79    unsigned char outbuf[1024];
80    unsigned char outtag[16];
81    OSSL_PARAM params[3] = {
82        OSSL_PARAM_END, OSSL_PARAM_END, OSSL_PARAM_END
83    };
84
85    printf("AES CCM Encrypt:\n");
86    printf("Plaintext:\n");
87    BIO_dump_fp(stdout, ccm_pt, sizeof(ccm_pt));
88
89    /* Create a context for the encrypt operation */
90    if ((ctx = EVP_CIPHER_CTX_new()) == NULL)
91        goto err;
92
93    /* Fetch the cipher implementation */
94    if ((cipher = EVP_CIPHER_fetch(libctx, "AES-192-CCM", propq)) == NULL)
95        goto err;
96
97    /* Set nonce length if default 96 bits is not appropriate */
98    params[0] = OSSL_PARAM_construct_size_t(OSSL_CIPHER_PARAM_AEAD_IVLEN,
99                                            &ccm_nonce_len);
100    /* Set tag length */
101    params[1] = OSSL_PARAM_construct_octet_string(OSSL_CIPHER_PARAM_AEAD_TAG,
102                                                  NULL, ccm_tag_len);
103
104    /*
105     * Initialise encrypt operation with the cipher & mode,
106     * nonce length and tag length parameters.
107     */
108    if (!EVP_EncryptInit_ex2(ctx, cipher, NULL, NULL, params))
109        goto err;
110
111    /* Initialise key and nonce */
112    if (!EVP_EncryptInit_ex(ctx, NULL, NULL, ccm_key, ccm_nonce))
113        goto err;
114
115    /* Set plaintext length: only needed if AAD is used */
116    if (!EVP_EncryptUpdate(ctx, NULL, &outlen, NULL, sizeof(ccm_pt)))
117        goto err;
118
119    /* Zero or one call to specify any AAD */
120    if (!EVP_EncryptUpdate(ctx, NULL, &outlen, ccm_adata, sizeof(ccm_adata)))
121        goto err;
122
123    /* Encrypt plaintext: can only be called once */
124    if (!EVP_EncryptUpdate(ctx, outbuf, &outlen, ccm_pt, sizeof(ccm_pt)))
125        goto err;
126
127    /* Output encrypted block */
128    printf("Ciphertext:\n");
129    BIO_dump_fp(stdout, outbuf, outlen);
130
131    /* Finalise: note get no output for CCM */
132    if (!EVP_EncryptFinal_ex(ctx, NULL, &tmplen))
133        goto err;
134
135    /* Get tag */
136    params[0] = OSSL_PARAM_construct_octet_string(OSSL_CIPHER_PARAM_AEAD_TAG,
137                                                  outtag, ccm_tag_len);
138    params[1] = OSSL_PARAM_construct_end();
139
140    if (!EVP_CIPHER_CTX_get_params(ctx, params))
141        goto err;
142
143    /* Output tag */
144    printf("Tag:\n");
145    BIO_dump_fp(stdout, outtag, ccm_tag_len);
146
147    ret = 1;
148err:
149    if (!ret)
150        ERR_print_errors_fp(stderr);
151
152    EVP_CIPHER_free(cipher);
153    EVP_CIPHER_CTX_free(ctx);
154
155    return ret;
156}
157
158int aes_ccm_decrypt(void)
159{
160    int ret = 0;
161    EVP_CIPHER_CTX *ctx;
162    EVP_CIPHER *cipher = NULL;
163    int outlen, rv;
164    unsigned char outbuf[1024];
165    size_t ccm_nonce_len = sizeof(ccm_nonce);
166    OSSL_PARAM params[3] = {
167        OSSL_PARAM_END, OSSL_PARAM_END, OSSL_PARAM_END
168    };
169
170    printf("AES CCM Decrypt:\n");
171    printf("Ciphertext:\n");
172    BIO_dump_fp(stdout, ccm_ct, sizeof(ccm_ct));
173
174    if ((ctx = EVP_CIPHER_CTX_new()) == NULL)
175        goto err;
176
177    /* Fetch the cipher implementation */
178    if ((cipher = EVP_CIPHER_fetch(libctx, "AES-192-CCM", propq)) == NULL)
179        goto err;
180
181    /* Set nonce length if default 96 bits is not appropriate */
182    params[0] = OSSL_PARAM_construct_size_t(OSSL_CIPHER_PARAM_AEAD_IVLEN,
183                                            &ccm_nonce_len);
184    /* Set tag length */
185    params[1] = OSSL_PARAM_construct_octet_string(OSSL_CIPHER_PARAM_AEAD_TAG,
186                                                  (unsigned char *)ccm_tag,
187                                                  sizeof(ccm_tag));
188    /*
189     * Initialise decrypt operation with the cipher & mode,
190     * nonce length and expected tag parameters.
191     */
192    if (!EVP_DecryptInit_ex2(ctx, cipher, NULL, NULL, params))
193        goto err;
194
195    /* Specify key and IV */
196    if (!EVP_DecryptInit_ex(ctx, NULL, NULL, ccm_key, ccm_nonce))
197        goto err;
198
199    /* Set ciphertext length: only needed if we have AAD */
200    if (!EVP_DecryptUpdate(ctx, NULL, &outlen, NULL, sizeof(ccm_ct)))
201        goto err;
202
203    /* Zero or one call to specify any AAD */
204    if (!EVP_DecryptUpdate(ctx, NULL, &outlen, ccm_adata, sizeof(ccm_adata)))
205        goto err;
206
207    /* Decrypt plaintext, verify tag: can only be called once */
208    rv = EVP_DecryptUpdate(ctx, outbuf, &outlen, ccm_ct, sizeof(ccm_ct));
209
210    /* Output decrypted block: if tag verify failed we get nothing */
211    if (rv > 0) {
212        printf("Tag verify successful!\nPlaintext:\n");
213        BIO_dump_fp(stdout, outbuf, outlen);
214    } else {
215        printf("Tag verify failed!\nPlaintext not available\n");
216        goto err;
217    }
218    ret = 1;
219err:
220    if (!ret)
221        ERR_print_errors_fp(stderr);
222
223    EVP_CIPHER_free(cipher);
224    EVP_CIPHER_CTX_free(ctx);
225
226    return ret;
227}
228
229int main(int argc, char **argv)
230{
231    if (!aes_ccm_encrypt())
232        return 1;
233
234    if (!aes_ccm_decrypt())
235        return 1;
236
237    return 0;
238}
239