1 /** 2 * \file cmac.h 3 * 4 * \brief This file contains CMAC definitions and functions. 5 * 6 * The Cipher-based Message Authentication Code (CMAC) Mode for 7 * Authentication is defined in <em>RFC-4493: The AES-CMAC Algorithm</em>. 8 * It is supported with AES and DES. 9 */ 10 /* 11 * Copyright The Mbed TLS Contributors 12 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later 13 */ 14 15 #ifndef MBEDTLS_CMAC_H 16 #define MBEDTLS_CMAC_H 17 #include "mbedtls/private_access.h" 18 19 #include "mbedtls/build_info.h" 20 21 #include "mbedtls/cipher.h" 22 23 #ifdef __cplusplus 24 extern "C" { 25 #endif 26 27 #define MBEDTLS_AES_BLOCK_SIZE 16 28 #define MBEDTLS_DES3_BLOCK_SIZE 8 29 30 /* We don't support Camellia or ARIA in this module */ 31 #if defined(MBEDTLS_AES_C) 32 #define MBEDTLS_CMAC_MAX_BLOCK_SIZE 16 /**< The longest block used by CMAC is that of AES. */ 33 #else 34 #define MBEDTLS_CMAC_MAX_BLOCK_SIZE 8 /**< The longest block used by CMAC is that of 3DES. */ 35 #endif 36 37 #if !defined(MBEDTLS_DEPRECATED_REMOVED) 38 /** The longest block supported by the cipher module. 39 * 40 * \deprecated 41 * For the maximum block size of a cipher supported by the CMAC module, 42 * use #MBEDTLS_CMAC_MAX_BLOCK_SIZE. 43 * For the maximum block size of a cipher supported by the cipher module, 44 * use #MBEDTLS_MAX_BLOCK_LENGTH. 45 */ 46 /* Before Mbed TLS 3.5, this was the maximum block size supported by the CMAC 47 * module, so it didn't take Camellia or ARIA into account. Since the name 48 * of the macro doesn't even convey "CMAC", this was misleading. Now the size 49 * is sufficient for any cipher, but the name is defined in cmac.h for 50 * backward compatibility. */ 51 #define MBEDTLS_CIPHER_BLKSIZE_MAX MBEDTLS_MAX_BLOCK_LENGTH 52 #endif /* MBEDTLS_DEPRECATED_REMOVED */ 53 54 #if !defined(MBEDTLS_CMAC_ALT) 55 56 /** 57 * The CMAC context structure. 58 */ 59 struct mbedtls_cmac_context_t { 60 /** The internal state of the CMAC algorithm. */ 61 unsigned char MBEDTLS_PRIVATE(state)[MBEDTLS_CMAC_MAX_BLOCK_SIZE]; 62 63 /** Unprocessed data - either data that was not block aligned and is still 64 * pending processing, or the final block. */ 65 unsigned char MBEDTLS_PRIVATE(unprocessed_block)[MBEDTLS_CMAC_MAX_BLOCK_SIZE]; 66 67 /** The length of data pending processing. */ 68 size_t MBEDTLS_PRIVATE(unprocessed_len); 69 }; 70 71 #else /* !MBEDTLS_CMAC_ALT */ 72 #include "cmac_alt.h" 73 #endif /* !MBEDTLS_CMAC_ALT */ 74 75 /** 76 * \brief This function starts a new CMAC computation 77 * by setting the CMAC key, and preparing to authenticate 78 * the input data. 79 * It must be called with an initialized cipher context. 80 * 81 * Once this function has completed, data can be supplied 82 * to the CMAC computation by calling 83 * mbedtls_cipher_cmac_update(). 84 * 85 * To start a CMAC computation using the same key as a previous 86 * CMAC computation, use mbedtls_cipher_cmac_finish(). 87 * 88 * \note When the CMAC implementation is supplied by an alternate 89 * implementation (through #MBEDTLS_CMAC_ALT), some ciphers 90 * may not be supported by that implementation, and thus 91 * return an error. Alternate implementations must support 92 * AES-128 and AES-256, and may support AES-192 and 3DES. 93 * 94 * \param ctx The cipher context used for the CMAC operation, initialized 95 * as one of the following types: MBEDTLS_CIPHER_AES_128_ECB, 96 * MBEDTLS_CIPHER_AES_192_ECB, MBEDTLS_CIPHER_AES_256_ECB, 97 * or MBEDTLS_CIPHER_DES_EDE3_ECB. 98 * \param key The CMAC key. 99 * \param keybits The length of the CMAC key in bits. 100 * Must be supported by the cipher. 101 * 102 * \return \c 0 on success. 103 * \return A cipher-specific error code on failure. 104 */ 105 int mbedtls_cipher_cmac_starts(mbedtls_cipher_context_t *ctx, 106 const unsigned char *key, size_t keybits); 107 108 /** 109 * \brief This function feeds an input buffer into an ongoing CMAC 110 * computation. 111 * 112 * The CMAC computation must have previously been started 113 * by calling mbedtls_cipher_cmac_starts() or 114 * mbedtls_cipher_cmac_reset(). 115 * 116 * Call this function as many times as needed to input the 117 * data to be authenticated. 118 * Once all of the required data has been input, 119 * call mbedtls_cipher_cmac_finish() to obtain the result 120 * of the CMAC operation. 121 * 122 * \param ctx The cipher context used for the CMAC operation. 123 * \param input The buffer holding the input data. 124 * \param ilen The length of the input data. 125 * 126 * \return \c 0 on success. 127 * \return #MBEDTLS_ERR_MD_BAD_INPUT_DATA 128 * if parameter verification fails. 129 */ 130 int mbedtls_cipher_cmac_update(mbedtls_cipher_context_t *ctx, 131 const unsigned char *input, size_t ilen); 132 133 /** 134 * \brief This function finishes an ongoing CMAC operation, and 135 * writes the result to the output buffer. 136 * 137 * It should be followed either by 138 * mbedtls_cipher_cmac_reset(), which starts another CMAC 139 * operation with the same key, or mbedtls_cipher_free(), 140 * which clears the cipher context. 141 * 142 * \param ctx The cipher context used for the CMAC operation. 143 * \param output The output buffer for the CMAC checksum result. 144 * 145 * \return \c 0 on success. 146 * \return #MBEDTLS_ERR_MD_BAD_INPUT_DATA 147 * if parameter verification fails. 148 */ 149 int mbedtls_cipher_cmac_finish(mbedtls_cipher_context_t *ctx, 150 unsigned char *output); 151 152 /** 153 * \brief This function starts a new CMAC operation with the same 154 * key as the previous one. 155 * 156 * It should be called after finishing the previous CMAC 157 * operation with mbedtls_cipher_cmac_finish(). 158 * After calling this function, 159 * call mbedtls_cipher_cmac_update() to supply the new 160 * CMAC operation with data. 161 * 162 * \param ctx The cipher context used for the CMAC operation. 163 * 164 * \return \c 0 on success. 165 * \return #MBEDTLS_ERR_MD_BAD_INPUT_DATA 166 * if parameter verification fails. 167 */ 168 int mbedtls_cipher_cmac_reset(mbedtls_cipher_context_t *ctx); 169 170 /** 171 * \brief This function calculates the full generic CMAC 172 * on the input buffer with the provided key. 173 * 174 * The function allocates the context, performs the 175 * calculation, and frees the context. 176 * 177 * The CMAC result is calculated as 178 * output = generic CMAC(cmac key, input buffer). 179 * 180 * \note When the CMAC implementation is supplied by an alternate 181 * implementation (through #MBEDTLS_CMAC_ALT), some ciphers 182 * may not be supported by that implementation, and thus 183 * return an error. Alternate implementations must support 184 * AES-128 and AES-256, and may support AES-192 and 3DES. 185 * 186 * \param cipher_info The cipher information. 187 * \param key The CMAC key. 188 * \param keylen The length of the CMAC key in bits. 189 * \param input The buffer holding the input data. 190 * \param ilen The length of the input data. 191 * \param output The buffer for the generic CMAC result. 192 * 193 * \return \c 0 on success. 194 * \return #MBEDTLS_ERR_MD_BAD_INPUT_DATA 195 * if parameter verification fails. 196 */ 197 int mbedtls_cipher_cmac(const mbedtls_cipher_info_t *cipher_info, 198 const unsigned char *key, size_t keylen, 199 const unsigned char *input, size_t ilen, 200 unsigned char *output); 201 202 #if defined(MBEDTLS_AES_C) 203 /** 204 * \brief This function implements the AES-CMAC-PRF-128 pseudorandom 205 * function, as defined in 206 * <em>RFC-4615: The Advanced Encryption Standard-Cipher-based 207 * Message Authentication Code-Pseudo-Random Function-128 208 * (AES-CMAC-PRF-128) Algorithm for the Internet Key 209 * Exchange Protocol (IKE).</em> 210 * 211 * \param key The key to use. 212 * \param key_len The key length in Bytes. 213 * \param input The buffer holding the input data. 214 * \param in_len The length of the input data in Bytes. 215 * \param output The buffer holding the generated 16 Bytes of 216 * pseudorandom output. 217 * 218 * \return \c 0 on success. 219 */ 220 int mbedtls_aes_cmac_prf_128(const unsigned char *key, size_t key_len, 221 const unsigned char *input, size_t in_len, 222 unsigned char output[16]); 223 #endif /* MBEDTLS_AES_C */ 224 225 #if defined(MBEDTLS_SELF_TEST) && (defined(MBEDTLS_AES_C) || defined(MBEDTLS_DES_C)) 226 /** 227 * \brief The CMAC checkup routine. 228 * 229 * \note In case the CMAC routines are provided by an alternative 230 * implementation (i.e. #MBEDTLS_CMAC_ALT is defined), the 231 * checkup routine will succeed even if the implementation does 232 * not support the less widely used AES-192 or 3DES primitives. 233 * The self-test requires at least AES-128 and AES-256 to be 234 * supported by the underlying implementation. 235 * 236 * \return \c 0 on success. 237 * \return \c 1 on failure. 238 */ 239 int mbedtls_cmac_self_test(int verbose); 240 #endif /* MBEDTLS_SELF_TEST && ( MBEDTLS_AES_C || MBEDTLS_DES_C ) */ 241 242 #ifdef __cplusplus 243 } 244 #endif 245 246 #endif /* MBEDTLS_CMAC_H */ 247
