1 /* Copyright (C) 1995-1998 Eric Young ([email protected]) 2 * All rights reserved. 3 * 4 * This package is an SSL implementation written 5 * by Eric Young ([email protected]). 6 * The implementation was written so as to conform with Netscapes SSL. 7 * 8 * This library is free for commercial and non-commercial use as long as 9 * the following conditions are aheared to. The following conditions 10 * apply to all code found in this distribution, be it the RC4, RSA, 11 * lhash, DES, etc., code; not just the SSL code. The SSL documentation 12 * included with this distribution is covered by the same copyright terms 13 * except that the holder is Tim Hudson ([email protected]). 14 * 15 * Copyright remains Eric Young's, and as such any Copyright notices in 16 * the code are not to be removed. 17 * If this package is used in a product, Eric Young should be given attribution 18 * as the author of the parts of the library used. 19 * This can be in the form of a textual message at program startup or 20 * in documentation (online or textual) provided with the package. 21 * 22 * Redistribution and use in source and binary forms, with or without 23 * modification, are permitted provided that the following conditions 24 * are met: 25 * 1. Redistributions of source code must retain the copyright 26 * notice, this list of conditions and the following disclaimer. 27 * 2. Redistributions in binary form must reproduce the above copyright 28 * notice, this list of conditions and the following disclaimer in the 29 * documentation and/or other materials provided with the distribution. 30 * 3. All advertising materials mentioning features or use of this software 31 * must display the following acknowledgement: 32 * "This product includes cryptographic software written by 33 * Eric Young ([email protected])" 34 * The word 'cryptographic' can be left out if the rouines from the library 35 * being used are not cryptographic related :-). 36 * 4. If you include any Windows specific code (or a derivative thereof) from 37 * the apps directory (application code) you must include an acknowledgement: 38 * "This product includes software written by Tim Hudson ([email protected])" 39 * 40 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND 41 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 42 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 43 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 44 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 45 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 46 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 48 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 49 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 50 * SUCH DAMAGE. 51 * 52 * The licence and distribution terms for any publically available version or 53 * derivative of this code cannot be changed. i.e. this code cannot simply be 54 * copied and put under another distribution licence 55 * [including the GNU Public Licence.] */ 56 57 #ifndef OPENSSL_HEADER_DH_H 58 #define OPENSSL_HEADER_DH_H 59 60 #include <openssl/base.h> 61 62 #include <openssl/thread.h> 63 64 #if defined(__cplusplus) 65 extern "C" { 66 #endif 67 68 69 // DH contains functions for performing Diffie-Hellman key agreement in 70 // multiplicative groups. 71 // 72 // This module is deprecated and retained for legacy reasons only. It is not 73 // considered a priority for performance or hardening work. Do not use it in 74 // new code. Use X25519 or ECDH with P-256 instead. 75 76 77 // Allocation and destruction. 78 // 79 // A |DH| object represents a Diffie-Hellman key or group parameters. A given 80 // object may be used concurrently on multiple threads by non-mutating 81 // functions, provided no other thread is concurrently calling a mutating 82 // function. Unless otherwise documented, functions which take a |const| pointer 83 // are non-mutating and functions which take a non-|const| pointer are mutating. 84 85 // DH_new returns a new, empty DH object or NULL on error. 86 OPENSSL_EXPORT DH *DH_new(void); 87 88 // DH_free decrements the reference count of |dh| and frees it if the reference 89 // count drops to zero. 90 OPENSSL_EXPORT void DH_free(DH *dh); 91 92 // DH_up_ref increments the reference count of |dh| and returns one. It does not 93 // mutate |dh| for thread-safety purposes and may be used concurrently. 94 OPENSSL_EXPORT int DH_up_ref(DH *dh); 95 96 97 // Properties. 98 99 // DH_bits returns the size of |dh|'s group modulus, in bits. 100 OPENSSL_EXPORT unsigned DH_bits(const DH *dh); 101 102 // DH_get0_pub_key returns |dh|'s public key. 103 OPENSSL_EXPORT const BIGNUM *DH_get0_pub_key(const DH *dh); 104 105 // DH_get0_priv_key returns |dh|'s private key, or NULL if |dh| is a public key. 106 OPENSSL_EXPORT const BIGNUM *DH_get0_priv_key(const DH *dh); 107 108 // DH_get0_p returns |dh|'s group modulus. 109 OPENSSL_EXPORT const BIGNUM *DH_get0_p(const DH *dh); 110 111 // DH_get0_q returns the size of |dh|'s subgroup, or NULL if it is unset. 112 OPENSSL_EXPORT const BIGNUM *DH_get0_q(const DH *dh); 113 114 // DH_get0_g returns |dh|'s group generator. 115 OPENSSL_EXPORT const BIGNUM *DH_get0_g(const DH *dh); 116 117 // DH_get0_key sets |*out_pub_key| and |*out_priv_key|, if non-NULL, to |dh|'s 118 // public and private key, respectively. If |dh| is a public key, the private 119 // key will be set to NULL. 120 OPENSSL_EXPORT void DH_get0_key(const DH *dh, const BIGNUM **out_pub_key, 121 const BIGNUM **out_priv_key); 122 123 // DH_set0_key sets |dh|'s public and private key to the specified values. If 124 // NULL, the field is left unchanged. On success, it takes ownership of each 125 // argument and returns one. Otherwise, it returns zero. 126 OPENSSL_EXPORT int DH_set0_key(DH *dh, BIGNUM *pub_key, BIGNUM *priv_key); 127 128 // DH_get0_pqg sets |*out_p|, |*out_q|, and |*out_g|, if non-NULL, to |dh|'s p, 129 // q, and g parameters, respectively. 130 OPENSSL_EXPORT void DH_get0_pqg(const DH *dh, const BIGNUM **out_p, 131 const BIGNUM **out_q, const BIGNUM **out_g); 132 133 // DH_set0_pqg sets |dh|'s p, q, and g parameters to the specified values. If 134 // NULL, the field is left unchanged. On success, it takes ownership of each 135 // argument and returns one. Otherwise, it returns zero. |q| may be NULL, but 136 // |p| and |g| must either be specified or already configured on |dh|. 137 OPENSSL_EXPORT int DH_set0_pqg(DH *dh, BIGNUM *p, BIGNUM *q, BIGNUM *g); 138 139 // DH_set_length sets the number of bits to use for the secret exponent when 140 // calling |DH_generate_key| on |dh| and returns one. If unset, 141 // |DH_generate_key| will use the bit length of p. 142 OPENSSL_EXPORT int DH_set_length(DH *dh, unsigned priv_length); 143 144 145 // Standard parameters. 146 147 // DH_get_rfc7919_2048 returns the group `ffdhe2048` from 148 // https://tools.ietf.org/html/rfc7919#appendix-A.1. It returns NULL if out 149 // of memory. 150 OPENSSL_EXPORT DH *DH_get_rfc7919_2048(void); 151 152 // BN_get_rfc3526_prime_1536 sets |*ret| to the 1536-bit MODP group from RFC 153 // 3526 and returns |ret|. If |ret| is NULL then a fresh |BIGNUM| is allocated 154 // and returned. It returns NULL on allocation failure. 155 OPENSSL_EXPORT BIGNUM *BN_get_rfc3526_prime_1536(BIGNUM *ret); 156 157 // BN_get_rfc3526_prime_2048 sets |*ret| to the 2048-bit MODP group from RFC 158 // 3526 and returns |ret|. If |ret| is NULL then a fresh |BIGNUM| is allocated 159 // and returned. It returns NULL on allocation failure. 160 OPENSSL_EXPORT BIGNUM *BN_get_rfc3526_prime_2048(BIGNUM *ret); 161 162 // BN_get_rfc3526_prime_3072 sets |*ret| to the 3072-bit MODP group from RFC 163 // 3526 and returns |ret|. If |ret| is NULL then a fresh |BIGNUM| is allocated 164 // and returned. It returns NULL on allocation failure. 165 OPENSSL_EXPORT BIGNUM *BN_get_rfc3526_prime_3072(BIGNUM *ret); 166 167 // BN_get_rfc3526_prime_4096 sets |*ret| to the 4096-bit MODP group from RFC 168 // 3526 and returns |ret|. If |ret| is NULL then a fresh |BIGNUM| is allocated 169 // and returned. It returns NULL on allocation failure. 170 OPENSSL_EXPORT BIGNUM *BN_get_rfc3526_prime_4096(BIGNUM *ret); 171 172 // BN_get_rfc3526_prime_6144 sets |*ret| to the 6144-bit MODP group from RFC 173 // 3526 and returns |ret|. If |ret| is NULL then a fresh |BIGNUM| is allocated 174 // and returned. It returns NULL on allocation failure. 175 OPENSSL_EXPORT BIGNUM *BN_get_rfc3526_prime_6144(BIGNUM *ret); 176 177 // BN_get_rfc3526_prime_8192 sets |*ret| to the 8192-bit MODP group from RFC 178 // 3526 and returns |ret|. If |ret| is NULL then a fresh |BIGNUM| is allocated 179 // and returned. It returns NULL on allocation failure. 180 OPENSSL_EXPORT BIGNUM *BN_get_rfc3526_prime_8192(BIGNUM *ret); 181 182 183 // Parameter generation. 184 185 #define DH_GENERATOR_2 2 186 #define DH_GENERATOR_5 5 187 188 // DH_generate_parameters_ex generates a suitable Diffie-Hellman group with a 189 // prime that is |prime_bits| long and stores it in |dh|. The generator of the 190 // group will be |generator|, which should be |DH_GENERATOR_2| unless there's a 191 // good reason to use a different value. The |cb| argument contains a callback 192 // function that will be called during the generation. See the documentation in 193 // |bn.h| about this. In addition to the callback invocations from |BN|, |cb| 194 // will also be called with |event| equal to three when the generation is 195 // complete. 196 OPENSSL_EXPORT int DH_generate_parameters_ex(DH *dh, int prime_bits, 197 int generator, BN_GENCB *cb); 198 199 200 // Diffie-Hellman operations. 201 202 // DH_generate_key generates a new, random, private key and stores it in 203 // |dh|, if |dh| does not already have a private key. Otherwise, it updates 204 // |dh|'s public key to match the private key. It returns one on success and 205 // zero on error. 206 OPENSSL_EXPORT int DH_generate_key(DH *dh); 207 208 // DH_compute_key_padded calculates the shared key between |dh| and |peers_key| 209 // and writes it as a big-endian integer into |out|, padded up to |DH_size| 210 // bytes. It returns the number of bytes written, which is always |DH_size|, or 211 // a negative number on error. |out| must have |DH_size| bytes of space. 212 // 213 // WARNING: this differs from the usual BoringSSL return-value convention. 214 // 215 // Note this function differs from |DH_compute_key| in that it preserves leading 216 // zeros in the secret. This function is the preferred variant. It matches PKCS 217 // #3 and avoids some side channel attacks. However, the two functions are not 218 // drop-in replacements for each other. Using a different variant than the 219 // application expects will result in sporadic key mismatches. 220 // 221 // Callers that expect a fixed-width secret should use this function over 222 // |DH_compute_key|. Callers that use either function should migrate to a modern 223 // primitive such as X25519 or ECDH with P-256 instead. 224 // 225 // This function does not mutate |dh| for thread-safety purposes and may be used 226 // concurrently. 227 OPENSSL_EXPORT int DH_compute_key_padded(uint8_t *out, const BIGNUM *peers_key, 228 DH *dh); 229 230 // DH_compute_key_hashed calculates the shared key between |dh| and |peers_key| 231 // and hashes it with the given |digest|. If the hash output is less than 232 // |max_out_len| bytes then it writes the hash output to |out| and sets 233 // |*out_len| to the number of bytes written. Otherwise it signals an error. It 234 // returns one on success or zero on error. 235 // 236 // NOTE: this follows the usual BoringSSL return-value convention, but that's 237 // different from |DH_compute_key| and |DH_compute_key_padded|. 238 // 239 // This function does not mutate |dh| for thread-safety purposes and may be used 240 // concurrently. 241 OPENSSL_EXPORT int DH_compute_key_hashed(DH *dh, uint8_t *out, size_t *out_len, 242 size_t max_out_len, 243 const BIGNUM *peers_key, 244 const EVP_MD *digest); 245 246 247 // Utility functions. 248 249 // DH_size returns the number of bytes in the DH group's prime. 250 OPENSSL_EXPORT int DH_size(const DH *dh); 251 252 // DH_num_bits returns the minimum number of bits needed to represent the 253 // absolute value of the DH group's prime. 254 OPENSSL_EXPORT unsigned DH_num_bits(const DH *dh); 255 256 #define DH_CHECK_P_NOT_PRIME 0x01 257 #define DH_CHECK_P_NOT_SAFE_PRIME 0x02 258 #define DH_CHECK_UNABLE_TO_CHECK_GENERATOR 0x04 259 #define DH_CHECK_NOT_SUITABLE_GENERATOR 0x08 260 #define DH_CHECK_Q_NOT_PRIME 0x10 261 #define DH_CHECK_INVALID_Q_VALUE 0x20 262 263 // These are compatibility defines. 264 #define DH_NOT_SUITABLE_GENERATOR DH_CHECK_NOT_SUITABLE_GENERATOR 265 #define DH_UNABLE_TO_CHECK_GENERATOR DH_CHECK_UNABLE_TO_CHECK_GENERATOR 266 267 // DH_check checks the suitability of |dh| as a Diffie-Hellman group. and sets 268 // |DH_CHECK_*| flags in |*out_flags| if it finds any errors. It returns one if 269 // |*out_flags| was successfully set and zero on error. 270 // 271 // Note: these checks may be quite computationally expensive. 272 OPENSSL_EXPORT int DH_check(const DH *dh, int *out_flags); 273 274 #define DH_CHECK_PUBKEY_TOO_SMALL 0x1 275 #define DH_CHECK_PUBKEY_TOO_LARGE 0x2 276 #define DH_CHECK_PUBKEY_INVALID 0x4 277 278 // DH_check_pub_key checks the suitability of |pub_key| as a public key for the 279 // DH group in |dh| and sets |DH_CHECK_PUBKEY_*| flags in |*out_flags| if it 280 // finds any errors. It returns one if |*out_flags| was successfully set and 281 // zero on error. 282 OPENSSL_EXPORT int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, 283 int *out_flags); 284 285 // DHparams_dup allocates a fresh |DH| and copies the parameters from |dh| into 286 // it. It returns the new |DH| or NULL on error. 287 OPENSSL_EXPORT DH *DHparams_dup(const DH *dh); 288 289 290 // ASN.1 functions. 291 292 // DH_parse_parameters decodes a DER-encoded DHParameter structure (PKCS #3) 293 // from |cbs| and advances |cbs|. It returns a newly-allocated |DH| or NULL on 294 // error. 295 OPENSSL_EXPORT DH *DH_parse_parameters(CBS *cbs); 296 297 // DH_marshal_parameters marshals |dh| as a DER-encoded DHParameter structure 298 // (PKCS #3) and appends the result to |cbb|. It returns one on success and zero 299 // on error. 300 OPENSSL_EXPORT int DH_marshal_parameters(CBB *cbb, const DH *dh); 301 302 303 // Deprecated functions. 304 305 // DH_generate_parameters behaves like |DH_generate_parameters_ex|, which is 306 // what you should use instead. It returns NULL on error, or a newly-allocated 307 // |DH| on success. This function is provided for compatibility only. 308 OPENSSL_EXPORT DH *DH_generate_parameters(int prime_len, int generator, 309 void (*callback)(int, int, void *), 310 void *cb_arg); 311 312 // d2i_DHparams parses a DER-encoded DHParameter structure (PKCS #3) from |len| 313 // bytes at |*inp|, as in |d2i_SAMPLE|. 314 // 315 // Use |DH_parse_parameters| instead. 316 OPENSSL_EXPORT DH *d2i_DHparams(DH **ret, const unsigned char **inp, long len); 317 318 // i2d_DHparams marshals |in| to a DER-encoded DHParameter structure (PKCS #3), 319 // as described in |i2d_SAMPLE|. 320 // 321 // Use |DH_marshal_parameters| instead. 322 OPENSSL_EXPORT int i2d_DHparams(const DH *in, unsigned char **outp); 323 324 // DH_compute_key behaves like |DH_compute_key_padded| but, contrary to PKCS #3, 325 // returns a variable-length shared key with leading zeros. It returns the 326 // number of bytes written, or a negative number on error. |out| must have 327 // |DH_size| bytes of space. 328 // 329 // WARNING: this differs from the usual BoringSSL return-value convention. 330 // 331 // Note this function's running time and memory access pattern leaks information 332 // about the shared secret. Particularly if |dh| is reused, this may result in 333 // side channel attacks such as https://raccoon-attack.com/. 334 // 335 // |DH_compute_key_padded| is the preferred variant and avoids the above 336 // attacks. However, the two functions are not drop-in replacements for each 337 // other. Using a different variant than the application expects will result in 338 // sporadic key mismatches. 339 // 340 // Callers that expect a fixed-width secret should use |DH_compute_key_padded| 341 // instead. Callers that use either function should migrate to a modern 342 // primitive such as X25519 or ECDH with P-256 instead. 343 // 344 // This function does not mutate |dh| for thread-safety purposes and may be used 345 // concurrently. 346 OPENSSL_EXPORT int DH_compute_key(uint8_t *out, const BIGNUM *peers_key, 347 DH *dh); 348 349 350 #if defined(__cplusplus) 351 } // extern C 352 353 extern "C++" { 354 355 BSSL_NAMESPACE_BEGIN 356 357 BORINGSSL_MAKE_DELETER(DH, DH_free) 358 BORINGSSL_MAKE_UP_REF(DH, DH_up_ref) 359 360 BSSL_NAMESPACE_END 361 362 } // extern C++ 363 364 #endif 365 366 #define DH_R_BAD_GENERATOR 100 367 #define DH_R_INVALID_PUBKEY 101 368 #define DH_R_MODULUS_TOO_LARGE 102 369 #define DH_R_NO_PRIVATE_VALUE 103 370 #define DH_R_DECODE_ERROR 104 371 #define DH_R_ENCODE_ERROR 105 372 #define DH_R_INVALID_PARAMETERS 106 373 374 #endif // OPENSSL_HEADER_DH_H 375