5 DH_generate_parameters_ex, DH_generate_parameters,
6 DH_check, DH_check_params,
7 DH_check_ex, DH_check_params_ex, DH_check_pub_key_ex
8 - generate and check Diffie-Hellman
13 #include <openssl/dh.h>
15 Deprecated since OpenSSL 3.0, can be hidden entirely by defining
16 B<OPENSSL_API_COMPAT> with a suitable version value, see
17 L<openssl_user_macros(7)>:
19 int DH_generate_parameters_ex(DH *dh, int prime_len, int generator, BN_GENCB *cb);
21 int DH_check(DH *dh, int *codes);
22 int DH_check_params(DH *dh, int *codes);
24 int DH_check_ex(const DH *dh);
25 int DH_check_params_ex(const DH *dh);
26 int DH_check_pub_key_ex(const DH *dh, const BIGNUM *pub_key);
28 Deprecated since OpenSSL 0.9.8, can be hidden entirely by defining
29 B<OPENSSL_API_COMPAT> with a suitable version value, see
30 L<openssl_user_macros(7)>:
32 DH *DH_generate_parameters(int prime_len, int generator,
33 void (*callback)(int, int, void *), void *cb_arg);
37 All of the functions described on this page are deprecated.
38 Applications should instead use L<EVP_PKEY_check(3)>,
39 L<EVP_PKEY_public_check(3)>, L<EVP_PKEY_private_check(3)> and
40 L<EVP_PKEY_param_check(3)>.
42 DH_generate_parameters_ex() generates Diffie-Hellman parameters that can
43 be shared among a group of users, and stores them in the provided B<DH>
44 structure. The pseudo-random number generator must be
45 seeded before calling it.
46 The parameters generated by DH_generate_parameters_ex() should not be used in
49 B<prime_len> is the length in bits of the safe prime to be generated.
50 B<generator> is a small number E<gt> 1, typically 2 or 5.
52 A callback function may be used to provide feedback about the progress
53 of the key generation. If B<cb> is not B<NULL>, it will be
54 called as described in L<BN_generate_prime(3)> while a random prime
55 number is generated, and when a prime has been found, B<BN_GENCB_call(cb, 3, 0)>
56 is called. See L<BN_generate_prime_ex(3)> for information on
57 the BN_GENCB_call() function.
59 DH_generate_parameters() is similar to DH_generate_prime_ex() but
60 expects an old-style callback function; see
61 L<BN_generate_prime(3)> for information on the old-style callback.
63 DH_check_params() confirms that the B<p> and B<g> are likely enough to
65 This is a lightweight check, if a more thorough check is needed, use
67 The value of B<*codes> is updated with any problems found.
68 If B<*codes> is zero then no problems were found, otherwise the
69 following bits may be set:
73 =item DH_CHECK_P_NOT_PRIME
75 The parameter B<p> has been determined to not being an odd prime.
76 Note that the lack of this bit doesn't guarantee that B<p> is a
79 =item DH_NOT_SUITABLE_GENERATOR
81 The generator B<g> is not suitable.
82 Note that the lack of this bit doesn't guarantee that B<g> is
83 suitable, unless B<p> is known to be a strong prime.
85 =item DH_MODULUS_TOO_SMALL
87 The modulus is too small.
89 =item DH_MODULUS_TOO_LARGE
91 The modulus is too large.
95 DH_check() confirms that the Diffie-Hellman parameters B<dh> are valid. The
96 value of B<*codes> is updated with any problems found. If B<*codes> is zero then
97 no problems were found, otherwise the following bits may be set:
101 =item DH_CHECK_P_NOT_PRIME
103 The parameter B<p> is not prime.
105 =item DH_CHECK_P_NOT_SAFE_PRIME
107 The parameter B<p> is not a safe prime and no B<q> value is present.
109 =item DH_UNABLE_TO_CHECK_GENERATOR
111 The generator B<g> cannot be checked for suitability.
113 =item DH_NOT_SUITABLE_GENERATOR
115 The generator B<g> is not suitable.
117 =item DH_CHECK_Q_NOT_PRIME
119 The parameter B<q> is not prime.
121 =item DH_CHECK_INVALID_Q_VALUE
123 The parameter B<q> is invalid.
125 =item DH_CHECK_INVALID_J_VALUE
127 The parameter B<j> is invalid.
131 DH_check_ex(), DH_check_params() and DH_check_pub_key_ex() are similar to
132 DH_check() and DH_check_params() respectively, but the error reasons are added
133 to the thread's error queue instead of provided as return values from the
138 DH_generate_parameters_ex(), DH_check() and DH_check_params() return 1
139 if the check could be performed, 0 otherwise.
141 DH_generate_parameters() returns a pointer to the DH structure or NULL if
142 the parameter generation fails.
144 DH_check_ex(), DH_check_params() and DH_check_pub_key_ex() return 1 if the
145 check is successful, 0 for failed.
147 The error codes can be obtained by L<ERR_get_error(3)>.
151 L<DH_new(3)>, L<ERR_get_error(3)>, L<RAND_bytes(3)>,
156 All of these functions were deprecated in OpenSSL 3.0.
158 DH_generate_parameters() was deprecated in OpenSSL 0.9.8; use
159 DH_generate_parameters_ex() instead.
163 Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.
165 Licensed under the Apache License 2.0 (the "License"). You may not use
166 this file except in compliance with the License. You can obtain a copy
167 in the file LICENSE in the source distribution or at
168 L<https://www.openssl.org/source/license.html>.