1 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
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.
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).
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.
22 * Redistribution and use in source and binary forms, with or without
23 * modification, are permitted provided that the following conditions
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)"
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
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.] */
57 #ifndef OPENSSL_HEADER_DH_H
58 #define OPENSSL_HEADER_DH_H
60 #include <openssl/base.h>
62 #include <openssl/engine.h>
63 #include <openssl/ex_data.h>
65 #if defined(__cplusplus)
70 /* DH contains functions for performing Diffie-Hellman key agreement in
71 * multiplicative groups. */
74 /* Allocation and destruction. */
76 /* DH_new returns a new, empty DH object or NULL on error. */
77 OPENSSL_EXPORT DH *DH_new(void);
79 /* DH_new_method acts the same as |DH_new| but takes an explicit |ENGINE|. */
80 OPENSSL_EXPORT DH *DH_new_method(const ENGINE *engine);
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);
86 /* DH_up_ref increments the reference count of |dh|. */
87 OPENSSL_EXPORT int DH_up_ref(DH *dh);
90 /* Standard parameters.
92 * These functions return new DH objects with standard parameters configured
93 * that use the given ENGINE, which may be NULL. They return NULL on allocation
96 /* These parameters are taken from RFC 5114. */
98 OPENSSL_EXPORT DH *DH_get_1024_160(const ENGINE *engine);
99 OPENSSL_EXPORT DH *DH_get_2048_224(const ENGINE *engine);
100 OPENSSL_EXPORT DH *DH_get_2048_256(const ENGINE *engine);
103 /* Parameter generation. */
105 #define DH_GENERATOR_2 2
106 #define DH_GENERATOR_5 5
108 /* DH_generate_parameters_ex generates a suitable Diffie-Hellman group with a
109 * prime that is |prime_bits| long and stores it in |dh|. The generator of the
110 * group will be |generator|, which should be |DH_GENERATOR_2| unless there's a
111 * good reason to use a different value. The |cb| argument contains a callback
112 * function that will be called during the generation. See the documentation in
113 * |bn.h| about this. In addition to the callback invocations from |BN|, |cb|
114 * will also be called with |event| equal to three when the generation is
116 OPENSSL_EXPORT int DH_generate_parameters_ex(DH *dh, int prime_bits,
117 int generator, BN_GENCB *cb);
120 /* Diffie-Hellman operations. */
122 /* DH_generate_key generates a new, random, private key and stores it in
123 * |dh|. It returns one on success and zero on error. */
124 OPENSSL_EXPORT int DH_generate_key(DH *dh);
126 /* DH_compute_key calculates the shared key between |dh| and |peers_key| and
127 * writes it as a big-endian integer into |out|, which must have |DH_size|
128 * bytes of space. It returns the number of bytes written, or a negative number
130 OPENSSL_EXPORT ssize_t
131 DH_compute_key(uint8_t *out, const BIGNUM *peers_key, DH *dh);
134 /* Utility functions. */
136 /* DH_size returns the number of bytes in the DH group's prime. */
137 OPENSSL_EXPORT int DH_size(const DH *dh);
139 #define DH_CHECK_P_NOT_PRIME 0x01
140 #define DH_CHECK_P_NOT_SAFE_PRIME 0x02
141 #define DH_CHECK_UNABLE_TO_CHECK_GENERATOR 0x04
142 #define DH_CHECK_NOT_SUITABLE_GENERATOR 0x08
143 #define DH_CHECK_Q_NOT_PRIME 0x10
144 #define DH_CHECK_INVALID_Q_VALUE 0x20
145 #define DH_CHECK_INVALID_J_VALUE 0x40
147 /* DH_check checks the suitability of |dh| as a Diffie-Hellman group. and sets
148 * |DH_CHECK_*| flags in |*out_flags| if it finds any errors. It returns one if
149 * |*out_flags| was successfully set and zero on error.
151 * Note: these checks may be quite computationally expensive. */
152 OPENSSL_EXPORT int DH_check(const DH *dh, int *out_flags);
154 #define DH_CHECK_PUBKEY_TOO_SMALL 1
155 #define DH_CHECK_PUBKEY_TOO_LARGE 2
157 /* DH_check_pub_key checks the suitability of |pub_key| as a public key for the
158 * DH group in |dh| and sets |DH_CHECK_PUBKEY_*| flags in |*out_flags| if it
159 * finds any errors. It returns one if |*out_flags| was successfully set and
161 OPENSSL_EXPORT int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key,
164 /* DHparams_dup allocates a fresh |DH| and copies the parameters from |dh| into
165 * it. It returns the new |DH| or NULL on error. */
166 OPENSSL_EXPORT DH *DHparams_dup(const DH *dh);
169 /* ASN.1 functions. */
171 /* d2i_DHparams parses an ASN.1, DER encoded Diffie-Hellman parameters
172 * structure from |len| bytes at |*inp|. If |ret| is not NULL then, on exit, a
173 * pointer to the result is in |*ret|. If |*ret| is already non-NULL on entry
174 * then the result is written directly into |*ret|, otherwise a fresh |DH| is
175 * allocated. On successful exit, |*inp| is advanced past the DER structure. It
176 * returns the result or NULL on error. */
177 OPENSSL_EXPORT DH *d2i_DHparams(DH **ret, const unsigned char **inp, long len);
179 /* i2d_DHparams marshals |in| to an ASN.1, DER structure. If |outp| is not NULL
180 * then the result is written to |*outp| and |*outp| is advanced just past the
181 * output. It returns the number of bytes in the result, whether written or
182 * not, or a negative value on error. */
183 OPENSSL_EXPORT int i2d_DHparams(const DH *in, unsigned char **outp);
186 /* ex_data functions.
188 * These functions are wrappers. See |ex_data.h| for details. */
190 OPENSSL_EXPORT int DH_get_ex_new_index(long argl, void *argp,
191 CRYPTO_EX_new *new_func,
192 CRYPTO_EX_dup *dup_func,
193 CRYPTO_EX_free *free_func);
194 OPENSSL_EXPORT int DH_set_ex_data(DH *d, int idx, void *arg);
195 OPENSSL_EXPORT void *DH_get_ex_data(DH *d, int idx);
198 /* dh_method contains function pointers to override the implementation of DH.
199 * See |engine.h| for details. */
201 struct openssl_method_common_st common;
203 /* app_data is an opaque pointer for the method to use. */
206 /* init is called just before the return of |DH_new_method|. It returns one
207 * on success or zero on error. */
210 /* finish is called before |dh| is destructed. */
211 void (*finish)(DH *dh);
213 /* generate_parameters is called by |DH_generate_parameters_ex|. */
214 int (*generate_parameters)(DH *dh, int prime_bits, int generator,
217 /* generate_parameters is called by |DH_generate_key|. */
218 int (*generate_key)(DH *dh);
220 /* generate_parameters is called by |DH_compute_key|. */
221 ssize_t (*compute_key)(DH *dh, uint8_t *out, const BIGNUM *pub_key);
229 BIGNUM *pub_key; /* g^x */
230 BIGNUM *priv_key; /* x */
232 /* priv_length contains the length, in bits, of the private value. If zero,
233 * the private value will be the same length as |p|. */
234 unsigned priv_length;
235 BN_MONT_CTX *method_mont_p;
237 /* Place holders if we want to do X9.42 DH */
246 CRYPTO_EX_DATA ex_data;
250 #if defined(__cplusplus)
254 #define DH_F_generate_parameters 100
255 #define DH_F_generate_key 101
256 #define DH_F_compute_key 102
257 #define DH_F_DH_new_method 103
258 #define DH_R_INVALID_PUBKEY 100
259 #define DH_R_BAD_GENERATOR 101
260 #define DH_R_MODULUS_TOO_LARGE 102
261 #define DH_R_NO_PRIVATE_VALUE 103
263 #endif /* OPENSSL_HEADER_DH_H */