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 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 } EVP_AEAD_CTX; 155 156 /* EVP_AEAD_MAX_KEY_LENGTH contains the maximum key length used by 157 * any AEAD defined in this header. */ 158 #define EVP_AEAD_MAX_KEY_LENGTH 80 159 160 /* EVP_AEAD_MAX_NONCE_LENGTH contains the maximum nonce length used by 161 * any AEAD defined in this header. */ 162 #define EVP_AEAD_MAX_NONCE_LENGTH 16 163 164 /* EVP_AEAD_MAX_OVERHEAD contains the maximum overhead used by any AEAD 165 * defined in this header. */ 166 #define EVP_AEAD_MAX_OVERHEAD 64 167 168 /* EVP_AEAD_DEFAULT_TAG_LENGTH is a magic value that can be passed to 169 * EVP_AEAD_CTX_init to indicate that the default tag length for an AEAD should 170 * be used. */ 171 #define EVP_AEAD_DEFAULT_TAG_LENGTH 0 172 173 /* EVP_AEAD_CTX_zero sets an uninitialized |ctx| to the zero state. It must be 174 * initialized with |EVP_AEAD_CTX_init| before use. It is safe, but not 175 * necessary, to call |EVP_AEAD_CTX_cleanup| in this state. This may be used for 176 * more uniform cleanup of |EVP_AEAD_CTX|. */ 177 OPENSSL_EXPORT void EVP_AEAD_CTX_zero(EVP_AEAD_CTX *ctx); 178 179 /* EVP_AEAD_CTX_init initializes |ctx| for the given AEAD algorithm. The |impl| 180 * argument is ignored and should be NULL. Authentication tags may be truncated 181 * by passing a size as |tag_len|. A |tag_len| of zero indicates the default 182 * tag length and this is defined as EVP_AEAD_DEFAULT_TAG_LENGTH for 183 * readability. 184 * 185 * Returns 1 on success. Otherwise returns 0 and pushes to the error stack. In 186 * the error case, you do not need to call |EVP_AEAD_CTX_cleanup|, but it's 187 * harmless to do so. */ 188 OPENSSL_EXPORT int EVP_AEAD_CTX_init(EVP_AEAD_CTX *ctx, const EVP_AEAD *aead, 189 const uint8_t *key, size_t key_len, 190 size_t tag_len, ENGINE *impl); 191 192 /* EVP_AEAD_CTX_cleanup frees any data allocated by |ctx|. It is a no-op to 193 * call |EVP_AEAD_CTX_cleanup| on a |EVP_AEAD_CTX| that has been |memset| to 194 * all zeros. */ 195 OPENSSL_EXPORT void EVP_AEAD_CTX_cleanup(EVP_AEAD_CTX *ctx); 196 197 /* EVP_AEAD_CTX_seal encrypts and authenticates |in_len| bytes from |in| and 198 * authenticates |ad_len| bytes from |ad| and writes the result to |out|. It 199 * returns one on success and zero otherwise. 200 * 201 * This function may be called (with the same |EVP_AEAD_CTX|) concurrently with 202 * itself or |EVP_AEAD_CTX_open|. 203 * 204 * At most |max_out_len| bytes are written to |out| and, in order to ensure 205 * success, |max_out_len| should be |in_len| plus the result of 206 * |EVP_AEAD_max_overhead|. On successful return, |*out_len| is set to the 207 * actual number of bytes written. 208 * 209 * The length of |nonce|, |nonce_len|, must be equal to the result of 210 * |EVP_AEAD_nonce_length| for this AEAD. 211 * 212 * |EVP_AEAD_CTX_seal| never results in a partial output. If |max_out_len| is 213 * insufficient, zero will be returned. (In this case, |*out_len| is set to 214 * zero.) 215 * 216 * If |in| and |out| alias then |out| must be == |in|. */ 217 OPENSSL_EXPORT int EVP_AEAD_CTX_seal(const EVP_AEAD_CTX *ctx, uint8_t *out, 218 size_t *out_len, size_t max_out_len, 219 const uint8_t *nonce, size_t nonce_len, 220 const uint8_t *in, size_t in_len, 221 const uint8_t *ad, size_t ad_len); 222 223 /* EVP_AEAD_CTX_open authenticates |in_len| bytes from |in| and |ad_len| bytes 224 * from |ad| and decrypts at most |in_len| bytes into |out|. It returns one on 225 * success and zero otherwise. 226 * 227 * This function may be called (with the same |EVP_AEAD_CTX|) concurrently with 228 * itself or |EVP_AEAD_CTX_seal|. 229 * 230 * At most |in_len| bytes are written to |out|. In order to ensure success, 231 * |max_out_len| should be at least |in_len|. On successful return, |*out_len| 232 * is set to the the actual number of bytes written. 233 * 234 * The length of |nonce|, |nonce_len|, must be equal to the result of 235 * |EVP_AEAD_nonce_length| for this AEAD. 236 * 237 * |EVP_AEAD_CTX_open| never results in a partial output. If |max_out_len| is 238 * insufficient, zero will be returned. (In this case, |*out_len| is set to 239 * zero.) 240 * 241 * If |in| and |out| alias then |out| must be == |in|. */ 242 OPENSSL_EXPORT int EVP_AEAD_CTX_open(const EVP_AEAD_CTX *ctx, uint8_t *out, 243 size_t *out_len, size_t max_out_len, 244 const uint8_t *nonce, size_t nonce_len, 245 const uint8_t *in, size_t in_len, 246 const uint8_t *ad, size_t ad_len); 247 248 /* EVP_AEAD_CTX_aead returns the underlying AEAD for |ctx|, or NULL if one has 249 * not been set. */ 250 OPENSSL_EXPORT const EVP_AEAD *EVP_AEAD_CTX_aead(const EVP_AEAD_CTX *ctx); 251 252 253 /* TLS-specific AEAD algorithms. 254 * 255 * These AEAD primitives do not meet the definition of generic AEADs. They are 256 * all specific to TLS and should not be used outside of that context. They must 257 * be initialized with |EVP_AEAD_CTX_init_with_direction|, are stateful, and may 258 * not be used concurrently. Any nonces are used as IVs, so they must be 259 * unpredictable. They only accept an |ad| parameter of length 11 (the standard 260 * TLS one with length omitted). */ 261 262 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_cbc_sha1_tls(void); 263 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_cbc_sha1_tls_implicit_iv(void); 264 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_cbc_sha256_tls(void); 265 266 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_cbc_sha1_tls(void); 267 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_cbc_sha1_tls_implicit_iv(void); 268 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_cbc_sha256_tls(void); 269 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_cbc_sha384_tls(void); 270 271 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_des_ede3_cbc_sha1_tls(void); 272 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_des_ede3_cbc_sha1_tls_implicit_iv(void); 273 274 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_null_sha1_tls(void); 275 276 277 /* SSLv3-specific AEAD algorithms. 278 * 279 * These AEAD primitives do not meet the definition of generic AEADs. They are 280 * all specific to SSLv3 and should not be used outside of that context. They 281 * must be initialized with |EVP_AEAD_CTX_init_with_direction|, are stateful, 282 * and may not be used concurrently. They only accept an |ad| parameter of 283 * length 9 (the standard TLS one with length and version omitted). */ 284 285 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_cbc_sha1_ssl3(void); 286 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_cbc_sha1_ssl3(void); 287 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_des_ede3_cbc_sha1_ssl3(void); 288 OPENSSL_EXPORT const EVP_AEAD *EVP_aead_null_sha1_ssl3(void); 289 290 291 /* Obscure functions. */ 292 293 /* evp_aead_direction_t denotes the direction of an AEAD operation. */ 294 enum evp_aead_direction_t { 295 evp_aead_open, 296 evp_aead_seal, 297 }; 298 299 /* EVP_AEAD_CTX_init_with_direction calls |EVP_AEAD_CTX_init| for normal 300 * AEADs. For TLS-specific and SSL3-specific AEADs, it initializes |ctx| for a 301 * given direction. */ 302 OPENSSL_EXPORT int EVP_AEAD_CTX_init_with_direction( 303 EVP_AEAD_CTX *ctx, const EVP_AEAD *aead, const uint8_t *key, size_t key_len, 304 size_t tag_len, enum evp_aead_direction_t dir); 305 306 /* EVP_AEAD_CTX_get_iv sets |*out_len| to the length of the IV for |ctx| and 307 * sets |*out_iv| to point to that many bytes of the current IV. This is only 308 * meaningful for AEADs with implicit IVs (i.e. CBC mode in SSLv3 and TLS 1.0). 309 * 310 * It returns one on success or zero on error. */ 311 OPENSSL_EXPORT int EVP_AEAD_CTX_get_iv(const EVP_AEAD_CTX *ctx, 312 const uint8_t **out_iv, size_t *out_len); 313 314 315 #if defined(__cplusplus) 316 } /* extern C */ 317 318 #if !defined(BORINGSSL_NO_CXX) 319 extern "C++" { 320 321 namespace bssl { 322 323 using ScopedEVP_AEAD_CTX = 324 internal::StackAllocated<EVP_AEAD_CTX, void, EVP_AEAD_CTX_zero, 325 EVP_AEAD_CTX_cleanup>; 326 327 } // namespace bssl 328 329 } // extern C++ 330 #endif 331 332 #endif 333 334 #endif /* OPENSSL_HEADER_AEAD_H */ 335
