1 /* Copyright (c) 2014, Google Inc. 2 * 3 * Permission to use, copy, modify, and/or distribute this software for any 4 * purpose with or without fee is hereby granted, provided that the above 5 * copyright notice and this permission notice appear in all copies. 6 * 7 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 8 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 9 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY 10 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 11 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION 12 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN 13 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ 14 15 #ifndef OPENSSL_HEADER_AEAD_H 16 #define OPENSSL_HEADER_AEAD_H 17 18 #include <openssl/base.h> 19 20 #if defined(__cplusplus) 21 extern "C" { 22 #endif 23 24 25 /* Authenticated Encryption with Additional Data. 26 * 27 * AEAD couples confidentiality and integrity in a single primitive. AEAD 28 * algorithms take a key and then can seal and open individual messages. Each 29 * message has a unique, per-message nonce and, optionally, additional data 30 * which is authenticated but not included in the ciphertext. 31 * 32 * The |EVP_AEAD_CTX_init| function initialises an |EVP_AEAD_CTX| structure and 33 * performs any precomputation needed to use |aead| with |key|. The length of 34 * the key, |key_len|, is given in bytes. 35 * 36 * The |tag_len| argument contains the length of the tags, in bytes, and allows 37 * for the processing of truncated authenticators. A zero value indicates that 38 * the default tag length should be used and this is defined as 39 * |EVP_AEAD_DEFAULT_TAG_LENGTH| in order to make the code clear. Using 40 * truncated tags increases an attacker's chance of creating a valid forgery. 41 * Be aware that the attacker's chance may increase more than exponentially as 42 * would naively be expected. 43 * 44 * When no longer needed, the initialised |EVP_AEAD_CTX| structure must be 45 * passed to |EVP_AEAD_CTX_cleanup|, which will deallocate any memory used. 46 * 47 * With an |EVP_AEAD_CTX| in hand, one can seal and open messages. These 48 * operations are intended to meet the standard notions of privacy and 49 * authenticity for authenticated encryption. For formal definitions see 50 * Bellare and Namprempre, "Authenticated encryption: relations among notions 51 * and analysis of the generic composition paradigm," Lecture Notes in Computer 52 * Science B<1976> (2000), 531545, 53 * http://www-cse.ucsd.edu/~mihir/papers/oem.html. 54 * 55 * When sealing messages, a nonce must be given. The length of the nonce is 56 * fixed by the AEAD in use and is returned by |EVP_AEAD_nonce_length|. *The 57 * nonce must be unique for all messages with the same key*. This is critically 58 * important - nonce reuse may completely undermine the security of the AEAD. 59 * Nonces may be predictable and public, so long as they are unique. Uniqueness 60 * may be achieved with a simple counter or, if large enough, may be generated 61 * randomly. The nonce must be passed into the "open" operation by the receiver 62 * so must either be implicit (e.g. a counter), or must be transmitted along 63 * with the sealed message. 64 * 65 * The "seal" and "open" operations are atomic - an entire message must be 66 * encrypted or decrypted in a single call. Large messages may have to be split 67 * up in order to accomodate this. When doing so, be mindful of the need not to 68 * repeat nonces and the possibility that an attacker could duplicate, reorder 69 * or drop message chunks. For example, using a single key for a given (large) 70 * message and sealing chunks with nonces counting from zero would be secure as 71 * long as the number of chunks was securely transmitted. (Otherwise an 72 * attacker could truncate the message by dropping chunks from the end.) 73 * 74 * The number of chunks could be transmitted by prefixing it to the plaintext, 75 * for example. This also assumes that no other message would ever use the same 76 * key otherwise the rule that nonces must be unique for a given key would be 77 * violated. 78 * 79 * The "seal" and "open" operations also permit additional data to be 80 * authenticated via the |ad| parameter. This data is not included in the 81 * ciphertext and must be identical for both the "seal" and "open" call. This 82 * permits implicit context to be authenticated but may be empty if not needed. 83 * 84 * The "seal" and "open" operations may work in-place if the |out| and |in| 85 * arguments are equal. They may also be used to shift the data left inside the 86 * same buffer if |out| is less than |in|. However, |out| may not point inside 87 * the input data otherwise the input may be overwritten before it has been 88 * read. This situation will cause an error. 89 * 90 * The "seal" and "open" operations return one on success and zero on error. */ 91 92 93 /* AEAD algorithms. */ 94 95 /* EVP_aead_aes_128_gcm is AES-128 in Galois Counter Mode. */ 96 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_gcm(void); 97 98 /* EVP_aead_aes_256_gcm is AES-256 in Galois Counter Mode. */ 99 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_gcm(void); 100 101 /* EVP_aead_chacha20_poly1305 is the AEAD built from ChaCha20 and 102 * Poly1305 as described in RFC 7539. */ 103 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_chacha20_poly1305(void); 104 105 /* EVP_aead_chacha20_poly1305_old is an AEAD built from ChaCha20 and 106 * Poly1305 that is used in the experimental ChaCha20-Poly1305 TLS cipher 107 * suites. */ 108 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_chacha20_poly1305_old(void); 109 110 /* EVP_aead_aes_128_key_wrap is AES-128 Key Wrap mode. This should never be 111 * used except to interoperate with existing systems that use this mode. 112 * 113 * If the nonce is empty then the default nonce will be used, otherwise it must 114 * be eight bytes long. The input must be a multiple of eight bytes long. No 115 * additional data can be given to this mode. */ 116 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_key_wrap(void); 117 118 /* EVP_aead_aes_256_key_wrap is AES-256 in Key Wrap mode. This should never be 119 * used except to interoperate with existing systems that use this mode. 120 * 121 * See |EVP_aead_aes_128_key_wrap| for details. */ 122 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_key_wrap(void); 123 124 /* EVP_aead_aes_128_ctr_hmac_sha256 is AES-128 in CTR mode with HMAC-SHA256 for 125 * authentication. The nonce is 12 bytes; the bottom 32-bits are used as the 126 * block counter, thus the maximum plaintext size is 64GB. */ 127 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_ctr_hmac_sha256(void); 128 129 /* EVP_aead_aes_256_ctr_hmac_sha256 is AES-256 in CTR mode with HMAC-SHA256 for 130 * authentication. See |EVP_aead_aes_128_ctr_hmac_sha256| for details. */ 131 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_ctr_hmac_sha256(void); 132 133 /* EVP_has_aes_hardware returns one if we enable hardware support for fast and 134 * constant-time AES-GCM. */ 135 OPENSSL_EXPORT int EVP_has_aes_hardware(void); 136 137 138 /* TLS-specific AEAD algorithms. 139 * 140 * These AEAD primitives do not meet the definition of generic AEADs. They are 141 * all specific to TLS and should not be used outside of that context. They must 142 * be initialized with |EVP_AEAD_CTX_init_with_direction|, are stateful, and may 143 * not be used concurrently. Any nonces are used as IVs, so they must be 144 * unpredictable. They only accept an |ad| parameter of length 11 (the standard 145 * TLS one with length omitted). */ 146 147 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_rc4_md5_tls(void); 148 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_rc4_sha1_tls(void); 149 150 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_cbc_sha1_tls(void); 151 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_cbc_sha1_tls_implicit_iv(void); 152 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_cbc_sha256_tls(void); 153 154 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_cbc_sha1_tls(void); 155 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_cbc_sha1_tls_implicit_iv(void); 156 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_cbc_sha256_tls(void); 157 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_cbc_sha384_tls(void); 158 159 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_des_ede3_cbc_sha1_tls(void); 160 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_des_ede3_cbc_sha1_tls_implicit_iv(void); 161 162 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_null_sha1_tls(void); 163 164 165 /* SSLv3-specific AEAD algorithms. 166 * 167 * These AEAD primitives do not meet the definition of generic AEADs. They are 168 * all specific to SSLv3 and should not be used outside of that context. They 169 * must be initialized with |EVP_AEAD_CTX_init_with_direction|, are stateful, 170 * and may not be used concurrently. They only accept an |ad| parameter of 171 * length 9 (the standard TLS one with length and version omitted). */ 172 173 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_rc4_md5_ssl3(void); 174 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_rc4_sha1_ssl3(void); 175 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_cbc_sha1_ssl3(void); 176 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_cbc_sha1_ssl3(void); 177 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_des_ede3_cbc_sha1_ssl3(void); 178 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_null_sha1_ssl3(void); 179 180 181 /* Utility functions. */ 182 183 /* EVP_AEAD_key_length returns the length, in bytes, of the keys used by 184 * |aead|. */ 185 OPENSSL_EXPORT size_t EVP_AEAD_key_length(const EVP_AEAD *aead); 186 187 /* EVP_AEAD_nonce_length returns the length, in bytes, of the per-message nonce 188 * for |aead|. */ 189 OPENSSL_EXPORT size_t EVP_AEAD_nonce_length(const EVP_AEAD *aead); 190 191 /* EVP_AEAD_max_overhead returns the maximum number of additional bytes added 192 * by the act of sealing data with |aead|. */ 193 OPENSSL_EXPORT size_t EVP_AEAD_max_overhead(const EVP_AEAD *aead); 194 195 /* EVP_AEAD_max_tag_len returns the maximum tag length when using |aead|. This 196 * is the largest value that can be passed as |tag_len| to 197 * |EVP_AEAD_CTX_init|. */ 198 OPENSSL_EXPORT size_t EVP_AEAD_max_tag_len(const EVP_AEAD *aead); 199 200 201 /* AEAD operations. */ 202 203 /* An EVP_AEAD_CTX represents an AEAD algorithm configured with a specific key 204 * and message-independent IV. */ 205 typedef struct evp_aead_ctx_st { 206 const EVP_AEAD *aead; 207 /* aead_state is an opaque pointer to whatever state the AEAD needs to 208 * maintain. */ 209 void *aead_state; 210 } EVP_AEAD_CTX; 211 212 /* EVP_AEAD_MAX_KEY_LENGTH contains the maximum key length used by 213 * any AEAD defined in this header. */ 214 #define EVP_AEAD_MAX_KEY_LENGTH 80 215 216 /* EVP_AEAD_MAX_NONCE_LENGTH contains the maximum nonce length used by 217 * any AEAD defined in this header. */ 218 #define EVP_AEAD_MAX_NONCE_LENGTH 16 219 220 /* EVP_AEAD_MAX_OVERHEAD contains the maximum overhead used by any AEAD 221 * defined in this header. */ 222 #define EVP_AEAD_MAX_OVERHEAD 64 223 224 /* EVP_AEAD_DEFAULT_TAG_LENGTH is a magic value that can be passed to 225 * EVP_AEAD_CTX_init to indicate that the default tag length for an AEAD should 226 * be used. */ 227 #define EVP_AEAD_DEFAULT_TAG_LENGTH 0 228 229 /* evp_aead_direction_t denotes the direction of an AEAD operation. */ 230 enum evp_aead_direction_t { 231 evp_aead_open, 232 evp_aead_seal, 233 }; 234 235 /* EVP_AEAD_CTX_zero sets an uninitialized |ctx| to the zero state. It must be 236 * initialized with |EVP_AEAD_CTX_init| before use. It is safe, but not 237 * necessary, to call |EVP_AEAD_CTX_cleanup| in this state. This may be used for 238 * more uniform cleanup of |EVP_AEAD_CTX|. */ 239 OPENSSL_EXPORT void EVP_AEAD_CTX_zero(EVP_AEAD_CTX *ctx); 240 241 /* EVP_AEAD_CTX_init initializes |ctx| for the given AEAD algorithm. The |impl| 242 * argument is ignored and should be NULL. Authentication tags may be truncated 243 * by passing a size as |tag_len|. A |tag_len| of zero indicates the default 244 * tag length and this is defined as EVP_AEAD_DEFAULT_TAG_LENGTH for 245 * readability. 246 * 247 * Returns 1 on success. Otherwise returns 0 and pushes to the error stack. In 248 * the error case, you do not need to call |EVP_AEAD_CTX_cleanup|, but it's 249 * harmless to do so. */ 250 OPENSSL_EXPORT int EVP_AEAD_CTX_init(EVP_AEAD_CTX *ctx, const EVP_AEAD *aead, 251 const uint8_t *key, size_t key_len, 252 size_t tag_len, ENGINE *impl); 253 254 /* EVP_AEAD_CTX_init_with_direction calls |EVP_AEAD_CTX_init| for normal 255 * AEADs. For TLS-specific and SSL3-specific AEADs, it initializes |ctx| for a 256 * given direction. */ 257 OPENSSL_EXPORT int EVP_AEAD_CTX_init_with_direction( 258 EVP_AEAD_CTX *ctx, const EVP_AEAD *aead, const uint8_t *key, size_t key_len, 259 size_t tag_len, enum evp_aead_direction_t dir); 260 261 /* EVP_AEAD_CTX_cleanup frees any data allocated by |ctx|. It is a no-op to 262 * call |EVP_AEAD_CTX_cleanup| on a |EVP_AEAD_CTX| that has been |memset| to 263 * all zeros. */ 264 OPENSSL_EXPORT void EVP_AEAD_CTX_cleanup(EVP_AEAD_CTX *ctx); 265 266 /* EVP_AEAD_CTX_seal encrypts and authenticates |in_len| bytes from |in| and 267 * authenticates |ad_len| bytes from |ad| and writes the result to |out|. It 268 * returns one on success and zero otherwise. 269 * 270 * This function may be called (with the same |EVP_AEAD_CTX|) concurrently with 271 * itself or |EVP_AEAD_CTX_open|. 272 * 273 * At most |max_out_len| bytes are written to |out| and, in order to ensure 274 * success, |max_out_len| should be |in_len| plus the result of 275 * |EVP_AEAD_max_overhead|. On successful return, |*out_len| is set to the 276 * actual number of bytes written. 277 * 278 * The length of |nonce|, |nonce_len|, must be equal to the result of 279 * |EVP_AEAD_nonce_length| for this AEAD. 280 * 281 * |EVP_AEAD_CTX_seal| never results in a partial output. If |max_out_len| is 282 * insufficient, zero will be returned. (In this case, |*out_len| is set to 283 * zero.) 284 * 285 * If |in| and |out| alias then |out| must be <= |in|. */ 286 OPENSSL_EXPORT int EVP_AEAD_CTX_seal(const EVP_AEAD_CTX *ctx, uint8_t *out, 287 size_t *out_len, size_t max_out_len, 288 const uint8_t *nonce, size_t nonce_len, 289 const uint8_t *in, size_t in_len, 290 const uint8_t *ad, size_t ad_len); 291 292 /* EVP_AEAD_CTX_open authenticates |in_len| bytes from |in| and |ad_len| bytes 293 * from |ad| and decrypts at most |in_len| bytes into |out|. It returns one on 294 * success and zero otherwise. 295 * 296 * This function may be called (with the same |EVP_AEAD_CTX|) concurrently with 297 * itself or |EVP_AEAD_CTX_seal|. 298 * 299 * At most |in_len| bytes are written to |out|. In order to ensure success, 300 * |max_out_len| should be at least |in_len|. On successful return, |*out_len| 301 * is set to the the actual number of bytes written. 302 * 303 * The length of |nonce|, |nonce_len|, must be equal to the result of 304 * |EVP_AEAD_nonce_length| for this AEAD. 305 * 306 * |EVP_AEAD_CTX_open| never results in a partial output. If |max_out_len| is 307 * insufficient, zero will be returned. (In this case, |*out_len| is set to 308 * zero.) 309 * 310 * If |in| and |out| alias then |out| must be <= |in|. */ 311 OPENSSL_EXPORT int EVP_AEAD_CTX_open(const EVP_AEAD_CTX *ctx, uint8_t *out, 312 size_t *out_len, size_t max_out_len, 313 const uint8_t *nonce, size_t nonce_len, 314 const uint8_t *in, size_t in_len, 315 const uint8_t *ad, size_t ad_len); 316 317 318 /* Obscure functions. */ 319 320 /* EVP_AEAD_CTX_get_rc4_state sets |*out_key| to point to an RC4 key structure. 321 * It returns one on success or zero if |ctx| doesn't have an RC4 key. */ 322 OPENSSL_EXPORT int EVP_AEAD_CTX_get_rc4_state(const EVP_AEAD_CTX *ctx, 323 const RC4_KEY **out_key); 324 325 /* EVP_AEAD_CTX_get_iv sets |*out_len| to the length of the IV for |ctx| and 326 * sets |*out_iv| to point to that many bytes of the current IV. This is only 327 * meaningful for AEADs with implicit IVs (i.e. CBC mode in SSLv3 and TLS 1.0). 328 * 329 * It returns one on success or zero on error. */ 330 OPENSSL_EXPORT int EVP_AEAD_CTX_get_iv(const EVP_AEAD_CTX *ctx, 331 const uint8_t **out_iv, size_t *out_len); 332 333 334 /* Deprecated functions. */ 335 336 /* EVP_aead_chacha20_poly1305_rfc7539 calls |EVP_aead_chacha20_poly1305|. 337 * 338 * TODO(davidben): Remove this. */ 339 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_chacha20_poly1305_rfc7539(void); 340 341 342 #if defined(__cplusplus) 343 } /* extern C */ 344 #endif 345 346 #endif /* OPENSSL_HEADER_AEAD_H */ 347
