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), 531–545, 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 accommodate 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. Otherwise, if |out| and |in| alias, input data may be 86 // overwritten before it is read. This situation will cause an error. 87 // 88 // The "seal" and "open" operations return one on success and zero on error. 89 90 91 // AEAD algorithms. 92 93 // EVP_aead_aes_128_gcm is AES-128 in Galois Counter Mode. 94 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_gcm(void); 95 96 // EVP_aead_aes_256_gcm is AES-256 in Galois Counter Mode. 97 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_gcm(void); 98 99 // EVP_aead_chacha20_poly1305 is the AEAD built from ChaCha20 and 100 // Poly1305 as described in RFC 7539. 101 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_chacha20_poly1305(void); 102 103 // EVP_aead_aes_128_ctr_hmac_sha256 is AES-128 in CTR mode with HMAC-SHA256 for 104 // authentication. The nonce is 12 bytes; the bottom 32-bits are used as the 105 // block counter, thus the maximum plaintext size is 64GB. 106 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_ctr_hmac_sha256(void); 107 108 // EVP_aead_aes_256_ctr_hmac_sha256 is AES-256 in CTR mode with HMAC-SHA256 for 109 // authentication. See |EVP_aead_aes_128_ctr_hmac_sha256| for details. 110 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_ctr_hmac_sha256(void); 111 112 // EVP_aead_aes_128_gcm_siv is AES-128 in GCM-SIV mode. See 113 // https://tools.ietf.org/html/draft-irtf-cfrg-gcmsiv-02 114 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_gcm_siv(void); 115 116 // EVP_aead_aes_256_gcm_siv is AES-256 in GCM-SIV mode. See 117 // https://tools.ietf.org/html/draft-irtf-cfrg-gcmsiv-02 118 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_gcm_siv(void); 119 120 // EVP_has_aes_hardware returns one if we enable hardware support for fast and 121 // constant-time AES-GCM. 122 OPENSSL_EXPORT int EVP_has_aes_hardware(void); 123 124 125 // Utility functions. 126 127 // EVP_AEAD_key_length returns the length, in bytes, of the keys used by 128 // |aead|. 129 OPENSSL_EXPORT size_t EVP_AEAD_key_length(const EVP_AEAD *aead); 130 131 // EVP_AEAD_nonce_length returns the length, in bytes, of the per-message nonce 132 // for |aead|. 133 OPENSSL_EXPORT size_t EVP_AEAD_nonce_length(const EVP_AEAD *aead); 134 135 // EVP_AEAD_max_overhead returns the maximum number of additional bytes added 136 // by the act of sealing data with |aead|. 137 OPENSSL_EXPORT size_t EVP_AEAD_max_overhead(const EVP_AEAD *aead); 138 139 // EVP_AEAD_max_tag_len returns the maximum tag length when using |aead|. This 140 // is the largest value that can be passed as |tag_len| to 141 // |EVP_AEAD_CTX_init|. 142 OPENSSL_EXPORT size_t EVP_AEAD_max_tag_len(const EVP_AEAD *aead); 143 144 145 // AEAD operations. 146 147 // An EVP_AEAD_CTX represents an AEAD algorithm configured with a specific key 148 // and message-independent IV. 149 typedef struct evp_aead_ctx_st { 150 const EVP_AEAD *aead; 151 // aead_state is an opaque pointer to whatever state the AEAD needs to 152 // maintain. 153 void *aead_state; 154 // tag_len may contain the actual length of the authentication tag if it is 155 // known at initialization time. 156 uint8_t tag_len; 157 } EVP_AEAD_CTX; 158 159 // EVP_AEAD_MAX_KEY_LENGTH contains the maximum key length used by 160 // any AEAD defined in this header. 161 #define EVP_AEAD_MAX_KEY_LENGTH 80 162 163 // EVP_AEAD_MAX_NONCE_LENGTH contains the maximum nonce length used by 164 // any AEAD defined in this header. 165 #define EVP_AEAD_MAX_NONCE_LENGTH 16 166 167 // EVP_AEAD_MAX_OVERHEAD contains the maximum overhead used by any AEAD 168 // defined in this header. 169 #define EVP_AEAD_MAX_OVERHEAD 64 170 171 // EVP_AEAD_DEFAULT_TAG_LENGTH is a magic value that can be passed to 172 // EVP_AEAD_CTX_init to indicate that the default tag length for an AEAD should 173 // be used. 174 #define EVP_AEAD_DEFAULT_TAG_LENGTH 0 175 176 // EVP_AEAD_CTX_zero sets an uninitialized |ctx| to the zero state. It must be 177 // initialized with |EVP_AEAD_CTX_init| before use. It is safe, but not 178 // necessary, to call |EVP_AEAD_CTX_cleanup| in this state. This may be used for 179 // more uniform cleanup of |EVP_AEAD_CTX|. 180 OPENSSL_EXPORT void EVP_AEAD_CTX_zero(EVP_AEAD_CTX *ctx); 181 182 // EVP_AEAD_CTX_new allocates an |EVP_AEAD_CTX|, calls |EVP_AEAD_CTX_init| and 183 // returns the |EVP_AEAD_CTX|, or NULL on error. 184 OPENSSL_EXPORT EVP_AEAD_CTX *EVP_AEAD_CTX_new(const EVP_AEAD *aead, 185 const uint8_t *key, 186 size_t key_len, size_t tag_len); 187 188 // EVP_AEAD_CTX_free calls |EVP_AEAD_CTX_cleanup| and |OPENSSL_free| on 189 // |ctx|. 190 OPENSSL_EXPORT void EVP_AEAD_CTX_free(EVP_AEAD_CTX *ctx); 191 192 // EVP_AEAD_CTX_init initializes |ctx| for the given AEAD algorithm. The |impl| 193 // argument is ignored and should be NULL. Authentication tags may be truncated 194 // by passing a size as |tag_len|. A |tag_len| of zero indicates the default 195 // tag length and this is defined as EVP_AEAD_DEFAULT_TAG_LENGTH for 196 // readability. 197 // 198 // Returns 1 on success. Otherwise returns 0 and pushes to the error stack. In 199 // the error case, you do not need to call |EVP_AEAD_CTX_cleanup|, but it's 200 // harmless to do so. 201 OPENSSL_EXPORT int EVP_AEAD_CTX_init(EVP_AEAD_CTX *ctx, const EVP_AEAD *aead, 202 const uint8_t *key, size_t key_len, 203 size_t tag_len, ENGINE *impl); 204 205 // EVP_AEAD_CTX_cleanup frees any data allocated by |ctx|. It is a no-op to 206 // call |EVP_AEAD_CTX_cleanup| on a |EVP_AEAD_CTX| that has been |memset| to 207 // all zeros. 208 OPENSSL_EXPORT void EVP_AEAD_CTX_cleanup(EVP_AEAD_CTX *ctx); 209 210 // EVP_AEAD_CTX_seal encrypts and authenticates |in_len| bytes from |in| and 211 // authenticates |ad_len| bytes from |ad| and writes the result to |out|. It 212 // returns one on success and zero otherwise. 213 // 214 // This function may be called concurrently with itself or any other seal/open 215 // function on the same |EVP_AEAD_CTX|. 216 // 217 // At most |max_out_len| bytes are written to |out| and, in order to ensure 218 // success, |max_out_len| should be |in_len| plus the result of 219 // |EVP_AEAD_max_overhead|. On successful return, |*out_len| is set to the 220 // actual number of bytes written. 221 // 222 // The length of |nonce|, |nonce_len|, must be equal to the result of 223 // |EVP_AEAD_nonce_length| for this AEAD. 224 // 225 // |EVP_AEAD_CTX_seal| never results in a partial output. If |max_out_len| is 226 // insufficient, zero will be returned. If any error occurs, |out| will be 227 // filled with zero bytes and |*out_len| set to zero. 228 // 229 // If |in| and |out| alias then |out| must be == |in|. 230 OPENSSL_EXPORT int EVP_AEAD_CTX_seal(const EVP_AEAD_CTX *ctx, uint8_t *out, 231 size_t *out_len, size_t max_out_len, 232 const uint8_t *nonce, size_t nonce_len, 233 const uint8_t *in, size_t in_len, 234 const uint8_t *ad, size_t ad_len); 235 236 // EVP_AEAD_CTX_open authenticates |in_len| bytes from |in| and |ad_len| bytes 237 // from |ad| and decrypts at most |in_len| bytes into |out|. It returns one on 238 // success and zero otherwise. 239 // 240 // This function may be called concurrently with itself or any other seal/open 241 // function on the same |EVP_AEAD_CTX|. 242 // 243 // At most |in_len| bytes are written to |out|. In order to ensure success, 244 // |max_out_len| should be at least |in_len|. On successful return, |*out_len| 245 // is set to the the actual number of bytes written. 246 // 247 // The length of |nonce|, |nonce_len|, must be equal to the result of 248 // |EVP_AEAD_nonce_length| for this AEAD. 249 // 250 // |EVP_AEAD_CTX_open| never results in a partial output. If |max_out_len| is 251 // insufficient, zero will be returned. If any error occurs, |out| will be 252 // filled with zero bytes and |*out_len| set to zero. 253 // 254 // If |in| and |out| alias then |out| must be == |in|. 255 OPENSSL_EXPORT int EVP_AEAD_CTX_open(const EVP_AEAD_CTX *ctx, uint8_t *out, 256 size_t *out_len, size_t max_out_len, 257 const uint8_t *nonce, size_t nonce_len, 258 const uint8_t *in, size_t in_len, 259 const uint8_t *ad, size_t ad_len); 260 261 // EVP_AEAD_CTX_seal_scatter encrypts and authenticates |in_len| bytes from |in| 262 // and authenticates |ad_len| bytes from |ad|. It writes |in_len| bytes of 263 // ciphertext to |out| and the authentication tag to |out_tag|. It returns one 264 // on success and zero otherwise. 265 // 266 // This function may be called concurrently with itself or any other seal/open 267 // function on the same |EVP_AEAD_CTX|. 268 // 269 // Exactly |in_len| bytes are written to |out|, and up to 270 // |EVP_AEAD_max_overhead+extra_in_len| bytes to |out_tag|. On successful 271 // return, |*out_tag_len| is set to the actual number of bytes written to 272 // |out_tag|. 273 // 274 // |extra_in| may point to an additional plaintext input buffer if the cipher 275 // supports it. If present, |extra_in_len| additional bytes of plaintext are 276 // encrypted and authenticated, and the ciphertext is written (before the tag) 277 // to |out_tag|. |max_out_tag_len| must be sized to allow for the additional 278 // |extra_in_len| bytes. 279 // 280 // The length of |nonce|, |nonce_len|, must be equal to the result of 281 // |EVP_AEAD_nonce_length| for this AEAD. 282 // 283 // |EVP_AEAD_CTX_seal_scatter| never results in a partial output. If 284 // |max_out_tag_len| is insufficient, zero will be returned. If any error 285 // occurs, |out| and |out_tag| will be filled with zero bytes and |*out_tag_len| 286 // set to zero. 287 // 288 // If |in| and |out| alias then |out| must be == |in|. |out_tag| may not alias 289 // any other argument. 290 OPENSSL_EXPORT int EVP_AEAD_CTX_seal_scatter( 291 const EVP_AEAD_CTX *ctx, uint8_t *out, 292 uint8_t *out_tag, size_t *out_tag_len, size_t max_out_tag_len, 293 const uint8_t *nonce, size_t nonce_len, 294 const uint8_t *in, size_t in_len, 295 const uint8_t *extra_in, size_t extra_in_len, 296 const uint8_t *ad, size_t ad_len); 297 298 // EVP_AEAD_CTX_open_gather decrypts and authenticates |in_len| bytes from |in| 299 // and authenticates |ad_len| bytes from |ad| using |in_tag_len| bytes of 300 // authentication tag from |in_tag|. If successful, it writes |in_len| bytes of 301 // plaintext to |out|. It returns one on success and zero otherwise. 302 // 303 // This function may be called concurrently with itself or any other seal/open 304 // function on the same |EVP_AEAD_CTX|. 305 // 306 // The length of |nonce|, |nonce_len|, must be equal to the result of 307 // |EVP_AEAD_nonce_length| for this AEAD. 308 // 309 // |EVP_AEAD_CTX_open_gather| never results in a partial output. If any error 310 // occurs, |out| will be filled with zero bytes. 311 // 312 // If |in| and |out| alias then |out| must be == |in|. 313 OPENSSL_EXPORT int EVP_AEAD_CTX_open_gather( 314 const EVP_AEAD_CTX *ctx, uint8_t *out, const uint8_t *nonce, 315 size_t nonce_len, const uint8_t *in, size_t in_len, const uint8_t *in_tag, 316 size_t in_tag_len, const uint8_t *ad, size_t ad_len); 317 318 // EVP_AEAD_CTX_aead returns the underlying AEAD for |ctx|, or NULL if one has 319 // not been set. 320 OPENSSL_EXPORT const EVP_AEAD *EVP_AEAD_CTX_aead(const EVP_AEAD_CTX *ctx); 321 322 323 // TLS-specific AEAD algorithms. 324 // 325 // These AEAD primitives do not meet the definition of generic AEADs. They are 326 // all specific to TLS and should not be used outside of that context. They must 327 // be initialized with |EVP_AEAD_CTX_init_with_direction|, are stateful, and may 328 // not be used concurrently. Any nonces are used as IVs, so they must be 329 // unpredictable. They only accept an |ad| parameter of length 11 (the standard 330 // TLS one with length omitted). 331 332 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_cbc_sha1_tls(void); 333 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_cbc_sha1_tls_implicit_iv(void); 334 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_cbc_sha256_tls(void); 335 336 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_cbc_sha1_tls(void); 337 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_cbc_sha1_tls_implicit_iv(void); 338 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_cbc_sha256_tls(void); 339 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_cbc_sha384_tls(void); 340 341 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_des_ede3_cbc_sha1_tls(void); 342 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_des_ede3_cbc_sha1_tls_implicit_iv(void); 343 344 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_null_sha1_tls(void); 345 346 // EVP_aead_aes_128_gcm_tls12 is AES-128 in Galois Counter Mode using the TLS 347 // 1.2 nonce construction. 348 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_gcm_tls12(void); 349 350 // EVP_aead_aes_256_gcm_tls12 is AES-256 in Galois Counter Mode using the TLS 351 // 1.2 nonce construction. 352 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_gcm_tls12(void); 353 354 355 // SSLv3-specific AEAD algorithms. 356 // 357 // These AEAD primitives do not meet the definition of generic AEADs. They are 358 // all specific to SSLv3 and should not be used outside of that context. They 359 // must be initialized with |EVP_AEAD_CTX_init_with_direction|, are stateful, 360 // and may not be used concurrently. They only accept an |ad| parameter of 361 // length 9 (the standard TLS one with length and version omitted). 362 363 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_cbc_sha1_ssl3(void); 364 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_cbc_sha1_ssl3(void); 365 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_des_ede3_cbc_sha1_ssl3(void); 366 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_null_sha1_ssl3(void); 367 368 369 // Obscure functions. 370 371 // evp_aead_direction_t denotes the direction of an AEAD operation. 372 enum evp_aead_direction_t { 373 evp_aead_open, 374 evp_aead_seal, 375 }; 376 377 // EVP_AEAD_CTX_init_with_direction calls |EVP_AEAD_CTX_init| for normal 378 // AEADs. For TLS-specific and SSL3-specific AEADs, it initializes |ctx| for a 379 // given direction. 380 OPENSSL_EXPORT int EVP_AEAD_CTX_init_with_direction( 381 EVP_AEAD_CTX *ctx, const EVP_AEAD *aead, const uint8_t *key, size_t key_len, 382 size_t tag_len, enum evp_aead_direction_t dir); 383 384 // EVP_AEAD_CTX_get_iv sets |*out_len| to the length of the IV for |ctx| and 385 // sets |*out_iv| to point to that many bytes of the current IV. This is only 386 // meaningful for AEADs with implicit IVs (i.e. CBC mode in SSLv3 and TLS 1.0). 387 // 388 // It returns one on success or zero on error. 389 OPENSSL_EXPORT int EVP_AEAD_CTX_get_iv(const EVP_AEAD_CTX *ctx, 390 const uint8_t **out_iv, size_t *out_len); 391 392 // EVP_AEAD_CTX_tag_len computes the exact byte length of the tag written by 393 // |EVP_AEAD_CTX_seal_scatter| and writes it to |*out_tag_len|. It returns one 394 // on success or zero on error. |in_len| and |extra_in_len| must equal the 395 // arguments of the same names passed to |EVP_AEAD_CTX_seal_scatter|. 396 OPENSSL_EXPORT int EVP_AEAD_CTX_tag_len(const EVP_AEAD_CTX *ctx, 397 size_t *out_tag_len, 398 const size_t in_len, 399 const size_t extra_in_len); 400 401 402 #if defined(__cplusplus) 403 } // extern C 404 405 #if !defined(BORINGSSL_NO_CXX) 406 extern "C++" { 407 408 namespace bssl { 409 410 using ScopedEVP_AEAD_CTX = 411 internal::StackAllocated<EVP_AEAD_CTX, void, EVP_AEAD_CTX_zero, 412 EVP_AEAD_CTX_cleanup>; 413 414 BORINGSSL_MAKE_DELETER(EVP_AEAD_CTX, EVP_AEAD_CTX_free) 415 416 } // namespace bssl 417 418 } // extern C++ 419 #endif 420 421 #endif 422 423 #endif // OPENSSL_HEADER_AEAD_H 424