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/ex_data.h>
63#include <openssl/thread.h>
64
65#if defined(__cplusplus)
66extern "C" {
67#endif
68
69
70// DH contains functions for performing Diffie-Hellman key agreement in
71// multiplicative groups.
72
73
74// Allocation and destruction.
75
76// DH_new returns a new, empty DH object or NULL on error.
77OPENSSL_EXPORT DH *DH_new(void);
78
79// DH_free decrements the reference count of |dh| and frees it if the reference
80// count drops to zero.
81OPENSSL_EXPORT void DH_free(DH *dh);
82
83// DH_up_ref increments the reference count of |dh| and returns one.
84OPENSSL_EXPORT int DH_up_ref(DH *dh);
85
86
87// Properties.
88
89// DH_get0_key sets |*out_pub_key| and |*out_priv_key|, if non-NULL, to |dh|'s
90// public and private key, respectively. If |dh| is a public key, the private
91// key will be set to NULL.
92OPENSSL_EXPORT void DH_get0_key(const DH *dh, const BIGNUM **out_pub_key,
93 const BIGNUM **out_priv_key);
94
95// DH_set0_key sets |dh|'s public and private key to the specified values. If
96// NULL, the field is left unchanged. On success, it takes ownership of each
97// argument and returns one. Otherwise, it returns zero.
98OPENSSL_EXPORT int DH_set0_key(DH *dh, BIGNUM *pub_key, BIGNUM *priv_key);
99
100// DH_get0_pqg sets |*out_p|, |*out_q|, and |*out_g|, if non-NULL, to |dh|'s p,
101// q, and g parameters, respectively.
102OPENSSL_EXPORT void DH_get0_pqg(const DH *dh, const BIGNUM **out_p,
103 const BIGNUM **out_q, const BIGNUM **out_g);
104
105// DH_set0_pqg sets |dh|'s p, q, and g parameters to the specified values. If
106// NULL, the field is left unchanged. On success, it takes ownership of each
107// argument and returns one. Otherwise, it returns zero. |q| may be NULL, but
108// |p| and |g| must either be specified or already configured on |dh|.
109OPENSSL_EXPORT int DH_set0_pqg(DH *dh, BIGNUM *p, BIGNUM *q, BIGNUM *g);
110
111
112// Standard parameters.
113
114// BN_get_rfc3526_prime_1536 sets |*ret| to the 1536-bit MODP group from RFC
115// 3526 and returns |ret|. If |ret| is NULL then a fresh |BIGNUM| is allocated
116// and returned. It returns NULL on allocation failure.
117OPENSSL_EXPORT BIGNUM *BN_get_rfc3526_prime_1536(BIGNUM *ret);
118
119
120// Parameter generation.
121
122#define DH_GENERATOR_2 2
123#define DH_GENERATOR_5 5
124
125// DH_generate_parameters_ex generates a suitable Diffie-Hellman group with a
126// prime that is |prime_bits| long and stores it in |dh|. The generator of the
127// group will be |generator|, which should be |DH_GENERATOR_2| unless there's a
128// good reason to use a different value. The |cb| argument contains a callback
129// function that will be called during the generation. See the documentation in
130// |bn.h| about this. In addition to the callback invocations from |BN|, |cb|
131// will also be called with |event| equal to three when the generation is
132// complete.
133OPENSSL_EXPORT int DH_generate_parameters_ex(DH *dh, int prime_bits,
134 int generator, BN_GENCB *cb);
135
136
137// Diffie-Hellman operations.
138
139// DH_generate_key generates a new, random, private key and stores it in
140// |dh|. It returns one on success and zero on error.
141OPENSSL_EXPORT int DH_generate_key(DH *dh);
142
143// DH_compute_key calculates the shared key between |dh| and |peers_key| and
144// writes it as a big-endian integer into |out|, which must have |DH_size|
145// bytes of space. It returns the number of bytes written, or a negative number
146// on error.
147OPENSSL_EXPORT int DH_compute_key(uint8_t *out, const BIGNUM *peers_key,
148 DH *dh);
149
150
151// Utility functions.
152
153// DH_size returns the number of bytes in the DH group's prime.
154OPENSSL_EXPORT int DH_size(const DH *dh);
155
156// DH_num_bits returns the minimum number of bits needed to represent the
157// absolute value of the DH group's prime.
158OPENSSL_EXPORT unsigned DH_num_bits(const DH *dh);
159
160#define DH_CHECK_P_NOT_PRIME 0x01
161#define DH_CHECK_P_NOT_SAFE_PRIME 0x02
162#define DH_CHECK_UNABLE_TO_CHECK_GENERATOR 0x04
163#define DH_CHECK_NOT_SUITABLE_GENERATOR 0x08
164#define DH_CHECK_Q_NOT_PRIME 0x10
165#define DH_CHECK_INVALID_Q_VALUE 0x20
166#define DH_CHECK_INVALID_J_VALUE 0x40
167
168// These are compatibility defines.
169#define DH_NOT_SUITABLE_GENERATOR DH_CHECK_NOT_SUITABLE_GENERATOR
170#define DH_UNABLE_TO_CHECK_GENERATOR DH_CHECK_UNABLE_TO_CHECK_GENERATOR
171
172// DH_check checks the suitability of |dh| as a Diffie-Hellman group. and sets
173// |DH_CHECK_*| flags in |*out_flags| if it finds any errors. It returns one if
174// |*out_flags| was successfully set and zero on error.
175//
176// Note: these checks may be quite computationally expensive.
177OPENSSL_EXPORT int DH_check(const DH *dh, int *out_flags);
178
179#define DH_CHECK_PUBKEY_TOO_SMALL 0x1
180#define DH_CHECK_PUBKEY_TOO_LARGE 0x2
181#define DH_CHECK_PUBKEY_INVALID 0x4
182
183// DH_check_pub_key checks the suitability of |pub_key| as a public key for the
184// DH group in |dh| and sets |DH_CHECK_PUBKEY_*| flags in |*out_flags| if it
185// finds any errors. It returns one if |*out_flags| was successfully set and
186// zero on error.
187OPENSSL_EXPORT int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key,
188 int *out_flags);
189
190// DHparams_dup allocates a fresh |DH| and copies the parameters from |dh| into
191// it. It returns the new |DH| or NULL on error.
192OPENSSL_EXPORT DH *DHparams_dup(const DH *dh);
193
194
195// ASN.1 functions.
196
197// DH_parse_parameters decodes a DER-encoded DHParameter structure (PKCS #3)
198// from |cbs| and advances |cbs|. It returns a newly-allocated |DH| or NULL on
199// error.
200OPENSSL_EXPORT DH *DH_parse_parameters(CBS *cbs);
201
202// DH_marshal_parameters marshals |dh| as a DER-encoded DHParameter structure
203// (PKCS #3) and appends the result to |cbb|. It returns one on success and zero
204// on error.
205OPENSSL_EXPORT int DH_marshal_parameters(CBB *cbb, const DH *dh);
206
207
208// ex_data functions.
209//
210// See |ex_data.h| for details.
211
212OPENSSL_EXPORT int DH_get_ex_new_index(long argl, void *argp,
213 CRYPTO_EX_unused *unused,
214 CRYPTO_EX_dup *dup_unused,
215 CRYPTO_EX_free *free_func);
216OPENSSL_EXPORT int DH_set_ex_data(DH *d, int idx, void *arg);
217OPENSSL_EXPORT void *DH_get_ex_data(DH *d, int idx);
218
219
220// Deprecated functions.
221
222// DH_generate_parameters behaves like |DH_generate_parameters_ex|, which is
223// what you should use instead. It returns NULL on error, or a newly-allocated
224// |DH| on success. This function is provided for compatibility only.
225OPENSSL_EXPORT DH *DH_generate_parameters(int prime_len, int generator,
226 void (*callback)(int, int, void *),
227 void *cb_arg);
228
229// d2i_DHparams parses an ASN.1, DER encoded Diffie-Hellman parameters structure
230// from |len| bytes at |*inp|. If |ret| is not NULL then, on exit, a pointer to
231// the result is in |*ret|. Note that, even if |*ret| is already non-NULL on
232// entry, it will not be written to. Rather, a fresh |DH| is allocated and the
233// previous one is freed.
234//
235// On successful exit, |*inp| is advanced past the DER structure. It
236// returns the result or NULL on error.
237//
238// Use |DH_parse_parameters| instead.
239OPENSSL_EXPORT DH *d2i_DHparams(DH **ret, const unsigned char **inp, long len);
240
241// i2d_DHparams marshals |in| to an ASN.1, DER structure. If |outp| is not NULL
242// then the result is written to |*outp| and |*outp| is advanced just past the
243// output. It returns the number of bytes in the result, whether written or
244// not, or a negative value on error.
245//
246// Use |DH_marshal_parameters| instead.
247OPENSSL_EXPORT int i2d_DHparams(const DH *in, unsigned char **outp);
248
249
250struct dh_st {
251 BIGNUM *p;
252 BIGNUM *g;
253 BIGNUM *pub_key; // g^x mod p
254 BIGNUM *priv_key; // x
255
256 // priv_length contains the length, in bits, of the private value. If zero,
257 // the private value will be the same length as |p|.
258 unsigned priv_length;
259
260 CRYPTO_MUTEX method_mont_p_lock;
261 BN_MONT_CTX *method_mont_p;
262
263 // Place holders if we want to do X9.42 DH
264 BIGNUM *q;
265 BIGNUM *j;
266 unsigned char *seed;
267 int seedlen;
268 BIGNUM *counter;
269
270 int flags;
271 CRYPTO_refcount_t references;
272 CRYPTO_EX_DATA ex_data;
273};
274
275
276#if defined(__cplusplus)
277} // extern C
278
279extern "C++" {
280
281BSSL_NAMESPACE_BEGIN
282
283BORINGSSL_MAKE_DELETER(DH, DH_free)
284BORINGSSL_MAKE_UP_REF(DH, DH_up_ref)
285
286BSSL_NAMESPACE_END
287
288} // extern C++
289
290#endif
291
292#define DH_R_BAD_GENERATOR 100
293#define DH_R_INVALID_PUBKEY 101
294#define DH_R_MODULUS_TOO_LARGE 102
295#define DH_R_NO_PRIVATE_VALUE 103
296#define DH_R_DECODE_ERROR 104
297#define DH_R_ENCODE_ERROR 105
298
299#endif // OPENSSL_HEADER_DH_H
300