1 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) 2 * All rights reserved. 3 * 4 * This package is an SSL implementation written 5 * by Eric Young (eay@cryptsoft.com). 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 (tjh@cryptsoft.com). 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 (eay@cryptsoft.com)" 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 (tjh@cryptsoft.com)" 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 // DH_new returns a new, empty DH object or NULL on error. 80 OPENSSL_EXPORT DH *DH_new(void); 81 82 // DH_free decrements the reference count of |dh| and frees it if the reference 83 // count drops to zero. 84 OPENSSL_EXPORT void DH_free(DH *dh); 85 86 // DH_up_ref increments the reference count of |dh| and returns one. 87 OPENSSL_EXPORT int DH_up_ref(DH *dh); 88 89 90 // Properties. 91 92 // DH_get0_pub_key returns |dh|'s public key. 93 OPENSSL_EXPORT const BIGNUM *DH_get0_pub_key(const DH *dh); 94 95 // DH_get0_priv_key returns |dh|'s private key, or NULL if |dh| is a public key. 96 OPENSSL_EXPORT const BIGNUM *DH_get0_priv_key(const DH *dh); 97 98 // DH_get0_p returns |dh|'s group modulus. 99 OPENSSL_EXPORT const BIGNUM *DH_get0_p(const DH *dh); 100 101 // DH_get0_q returns the size of |dh|'s subgroup, or NULL if it is unset. 102 OPENSSL_EXPORT const BIGNUM *DH_get0_q(const DH *dh); 103 104 // DH_get0_g returns |dh|'s group generator. 105 OPENSSL_EXPORT const BIGNUM *DH_get0_g(const DH *dh); 106 107 // DH_get0_key sets |*out_pub_key| and |*out_priv_key|, if non-NULL, to |dh|'s 108 // public and private key, respectively. If |dh| is a public key, the private 109 // key will be set to NULL. 110 OPENSSL_EXPORT void DH_get0_key(const DH *dh, const BIGNUM **out_pub_key, 111 const BIGNUM **out_priv_key); 112 113 // DH_set0_key sets |dh|'s public and private key to the specified values. If 114 // NULL, the field is left unchanged. On success, it takes ownership of each 115 // argument and returns one. Otherwise, it returns zero. 116 OPENSSL_EXPORT int DH_set0_key(DH *dh, BIGNUM *pub_key, BIGNUM *priv_key); 117 118 // DH_get0_pqg sets |*out_p|, |*out_q|, and |*out_g|, if non-NULL, to |dh|'s p, 119 // q, and g parameters, respectively. 120 OPENSSL_EXPORT void DH_get0_pqg(const DH *dh, const BIGNUM **out_p, 121 const BIGNUM **out_q, const BIGNUM **out_g); 122 123 // DH_set0_pqg sets |dh|'s p, q, and g parameters 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. |q| may be NULL, but 126 // |p| and |g| must either be specified or already configured on |dh|. 127 OPENSSL_EXPORT int DH_set0_pqg(DH *dh, BIGNUM *p, BIGNUM *q, BIGNUM *g); 128 129 // DH_set_length sets the number of bits to use for the secret exponent when 130 // calling |DH_generate_key| on |dh| and returns one. If unset, 131 // |DH_generate_key| will use the bit length of p. 132 OPENSSL_EXPORT int DH_set_length(DH *dh, unsigned priv_length); 133 134 135 // Standard parameters. 136 137 // BN_get_rfc3526_prime_1536 sets |*ret| to the 1536-bit MODP group from RFC 138 // 3526 and returns |ret|. If |ret| is NULL then a fresh |BIGNUM| is allocated 139 // and returned. It returns NULL on allocation failure. 140 OPENSSL_EXPORT BIGNUM *BN_get_rfc3526_prime_1536(BIGNUM *ret); 141 142 // DH_get_rfc7919_2048 returns the group `ffdhe2048` from 143 // https://tools.ietf.org/html/rfc7919#appendix-A.1. It returns NULL if out 144 // of memory. 145 OPENSSL_EXPORT DH *DH_get_rfc7919_2048(void); 146 147 148 // Parameter generation. 149 150 #define DH_GENERATOR_2 2 151 #define DH_GENERATOR_5 5 152 153 // DH_generate_parameters_ex generates a suitable Diffie-Hellman group with a 154 // prime that is |prime_bits| long and stores it in |dh|. The generator of the 155 // group will be |generator|, which should be |DH_GENERATOR_2| unless there's a 156 // good reason to use a different value. The |cb| argument contains a callback 157 // function that will be called during the generation. See the documentation in 158 // |bn.h| about this. In addition to the callback invocations from |BN|, |cb| 159 // will also be called with |event| equal to three when the generation is 160 // complete. 161 OPENSSL_EXPORT int DH_generate_parameters_ex(DH *dh, int prime_bits, 162 int generator, BN_GENCB *cb); 163 164 165 // Diffie-Hellman operations. 166 167 // DH_generate_key generates a new, random, private key and stores it in 168 // |dh|. It returns one on success and zero on error. 169 OPENSSL_EXPORT int DH_generate_key(DH *dh); 170 171 // DH_compute_key_padded calculates the shared key between |dh| and |peers_key| 172 // and writes it as a big-endian integer into |out|, padded up to |DH_size| 173 // bytes. It returns the number of bytes written, which is always |DH_size|, or 174 // a negative number on error. |out| must have |DH_size| bytes of space. 175 // 176 // WARNING: this differs from the usual BoringSSL return-value convention. 177 // 178 // Note this function differs from |DH_compute_key| in that it preserves leading 179 // zeros in the secret. This function is the preferred variant. It matches PKCS 180 // #3 and avoids some side channel attacks. However, the two functions are not 181 // drop-in replacements for each other. Using a different variant than the 182 // application expects will result in sporadic key mismatches. 183 // 184 // Callers that expect a fixed-width secret should use this function over 185 // |DH_compute_key|. Callers that use either function should migrate to a modern 186 // primitive such as X25519 or ECDH with P-256 instead. 187 OPENSSL_EXPORT int DH_compute_key_padded(uint8_t *out, const BIGNUM *peers_key, 188 DH *dh); 189 190 // DH_compute_key_hashed calculates the shared key between |dh| and |peers_key| 191 // and hashes it with the given |digest|. If the hash output is less than 192 // |max_out_len| bytes then it writes the hash output to |out| and sets 193 // |*out_len| to the number of bytes written. Otherwise it signals an error. It 194 // returns one on success or zero on error. 195 // 196 // NOTE: this follows the usual BoringSSL return-value convention, but that's 197 // different from |DH_compute_key| and |DH_compute_key_padded|. 198 OPENSSL_EXPORT int DH_compute_key_hashed(DH *dh, uint8_t *out, size_t *out_len, 199 size_t max_out_len, 200 const BIGNUM *peers_key, 201 const EVP_MD *digest); 202 203 204 // Utility functions. 205 206 // DH_size returns the number of bytes in the DH group's prime. 207 OPENSSL_EXPORT int DH_size(const DH *dh); 208 209 // DH_num_bits returns the minimum number of bits needed to represent the 210 // absolute value of the DH group's prime. 211 OPENSSL_EXPORT unsigned DH_num_bits(const DH *dh); 212 213 #define DH_CHECK_P_NOT_PRIME 0x01 214 #define DH_CHECK_P_NOT_SAFE_PRIME 0x02 215 #define DH_CHECK_UNABLE_TO_CHECK_GENERATOR 0x04 216 #define DH_CHECK_NOT_SUITABLE_GENERATOR 0x08 217 #define DH_CHECK_Q_NOT_PRIME 0x10 218 #define DH_CHECK_INVALID_Q_VALUE 0x20 219 #define DH_CHECK_INVALID_J_VALUE 0x40 220 221 // These are compatibility defines. 222 #define DH_NOT_SUITABLE_GENERATOR DH_CHECK_NOT_SUITABLE_GENERATOR 223 #define DH_UNABLE_TO_CHECK_GENERATOR DH_CHECK_UNABLE_TO_CHECK_GENERATOR 224 225 // DH_check checks the suitability of |dh| as a Diffie-Hellman group. and sets 226 // |DH_CHECK_*| flags in |*out_flags| if it finds any errors. It returns one if 227 // |*out_flags| was successfully set and zero on error. 228 // 229 // Note: these checks may be quite computationally expensive. 230 OPENSSL_EXPORT int DH_check(const DH *dh, int *out_flags); 231 232 #define DH_CHECK_PUBKEY_TOO_SMALL 0x1 233 #define DH_CHECK_PUBKEY_TOO_LARGE 0x2 234 #define DH_CHECK_PUBKEY_INVALID 0x4 235 236 // DH_check_pub_key checks the suitability of |pub_key| as a public key for the 237 // DH group in |dh| and sets |DH_CHECK_PUBKEY_*| flags in |*out_flags| if it 238 // finds any errors. It returns one if |*out_flags| was successfully set and 239 // zero on error. 240 OPENSSL_EXPORT int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, 241 int *out_flags); 242 243 // DHparams_dup allocates a fresh |DH| and copies the parameters from |dh| into 244 // it. It returns the new |DH| or NULL on error. 245 OPENSSL_EXPORT DH *DHparams_dup(const DH *dh); 246 247 248 // ASN.1 functions. 249 250 // DH_parse_parameters decodes a DER-encoded DHParameter structure (PKCS #3) 251 // from |cbs| and advances |cbs|. It returns a newly-allocated |DH| or NULL on 252 // error. 253 OPENSSL_EXPORT DH *DH_parse_parameters(CBS *cbs); 254 255 // DH_marshal_parameters marshals |dh| as a DER-encoded DHParameter structure 256 // (PKCS #3) and appends the result to |cbb|. It returns one on success and zero 257 // on error. 258 OPENSSL_EXPORT int DH_marshal_parameters(CBB *cbb, const DH *dh); 259 260 261 // Deprecated functions. 262 263 // DH_generate_parameters behaves like |DH_generate_parameters_ex|, which is 264 // what you should use instead. It returns NULL on error, or a newly-allocated 265 // |DH| on success. This function is provided for compatibility only. 266 OPENSSL_EXPORT DH *DH_generate_parameters(int prime_len, int generator, 267 void (*callback)(int, int, void *), 268 void *cb_arg); 269 270 // d2i_DHparams parses a DER-encoded DHParameter structure (PKCS #3) from |len| 271 // bytes at |*inp|, as in |d2i_SAMPLE|. 272 // 273 // Use |DH_parse_parameters| instead. 274 OPENSSL_EXPORT DH *d2i_DHparams(DH **ret, const unsigned char **inp, long len); 275 276 // i2d_DHparams marshals |in| to a DER-encoded DHParameter structure (PKCS #3), 277 // as described in |i2d_SAMPLE|. 278 // 279 // Use |DH_marshal_parameters| instead. 280 OPENSSL_EXPORT int i2d_DHparams(const DH *in, unsigned char **outp); 281 282 // DH_compute_key behaves like |DH_compute_key_padded| but, contrary to PKCS #3, 283 // returns a variable-length shared key with leading zeros. It returns the 284 // number of bytes written, or a negative number on error. |out| must have 285 // |DH_size| bytes of space. 286 // 287 // WARNING: this differs from the usual BoringSSL return-value convention. 288 // 289 // Note this function's running time and memory access pattern leaks information 290 // about the shared secret. Particularly if |dh| is reused, this may result in 291 // side channel attacks such as https://raccoon-attack.com/. 292 // 293 // |DH_compute_key_padded| is the preferred variant and avoids the above 294 // attacks. However, the two functions are not drop-in replacements for each 295 // other. Using a different variant than the application expects will result in 296 // sporadic key mismatches. 297 // 298 // Callers that expect a fixed-width secret should use |DH_compute_key_padded| 299 // instead. Callers that use either function should migrate to a modern 300 // primitive such as X25519 or ECDH with P-256 instead. 301 OPENSSL_EXPORT int DH_compute_key(uint8_t *out, const BIGNUM *peers_key, 302 DH *dh); 303 304 305 struct dh_st { 306 BIGNUM *p; 307 BIGNUM *g; 308 BIGNUM *pub_key; // g^x mod p 309 BIGNUM *priv_key; // x 310 311 // priv_length contains the length, in bits, of the private value. If zero, 312 // the private value will be the same length as |p|. 313 unsigned priv_length; 314 315 CRYPTO_MUTEX method_mont_p_lock; 316 BN_MONT_CTX *method_mont_p; 317 318 // Place holders if we want to do X9.42 DH 319 BIGNUM *q; 320 BIGNUM *j; 321 unsigned char *seed; 322 int seedlen; 323 BIGNUM *counter; 324 325 int flags; 326 CRYPTO_refcount_t references; 327 }; 328 329 330 #if defined(__cplusplus) 331 } // extern C 332 333 extern "C++" { 334 335 BSSL_NAMESPACE_BEGIN 336 337 BORINGSSL_MAKE_DELETER(DH, DH_free) 338 BORINGSSL_MAKE_UP_REF(DH, DH_up_ref) 339 340 BSSL_NAMESPACE_END 341 342 } // extern C++ 343 344 #endif 345 346 #define DH_R_BAD_GENERATOR 100 347 #define DH_R_INVALID_PUBKEY 101 348 #define DH_R_MODULUS_TOO_LARGE 102 349 #define DH_R_NO_PRIVATE_VALUE 103 350 #define DH_R_DECODE_ERROR 104 351 #define DH_R_ENCODE_ERROR 105 352 353 #endif // OPENSSL_HEADER_DH_H 354