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 */ 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 OSSL_LIB_CTX *libctx = NULL; 68 const char *propq = NULL; 69 70 71 int 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; 148 err: 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 } 157 158 int 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; 219 err: 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 } 228 229 int 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