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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)
66 extern "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.
77 OPENSSL_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.
81 OPENSSL_EXPORT void DH_free(DH *dh);
82 
83 // DH_up_ref increments the reference count of |dh| and returns one.
84 OPENSSL_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.
92 OPENSSL_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.
98 OPENSSL_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.
102 OPENSSL_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|.
109 OPENSSL_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.
117 OPENSSL_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.
133 OPENSSL_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.
141 OPENSSL_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.
147 OPENSSL_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.
154 OPENSSL_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.
158 OPENSSL_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.
177 OPENSSL_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.
187 OPENSSL_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.
192 OPENSSL_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.
200 OPENSSL_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.
205 OPENSSL_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 
212 OPENSSL_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);
216 OPENSSL_EXPORT int DH_set_ex_data(DH *d, int idx, void *arg);
217 OPENSSL_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.
225 OPENSSL_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.
239 OPENSSL_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.
247 OPENSSL_EXPORT int i2d_DHparams(const DH *in, unsigned char **outp);
248 
249 
250 struct 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 
279 extern "C++" {
280 
281 BSSL_NAMESPACE_BEGIN
282 
283 BORINGSSL_MAKE_DELETER(DH, DH_free)
284 BORINGSSL_MAKE_UP_REF(DH, DH_up_ref)
285 
286 BSSL_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