5 DH_generate_parameters_ex, DH_generate_parameters,
6 DH_check - generate and check Diffie-Hellman parameters
10 #include <openssl/dh.h>
12 int DH_generate_parameters_ex(DH *dh, int prime_len,int generator, BN_GENCB *cb);
14 int DH_check(DH *dh, int *codes);
18 #if OPENSSL_API_COMPAT < 0x00908000L
19 DH *DH_generate_parameters(int prime_len, int generator,
20 void (*callback)(int, int, void *), void *cb_arg);
25 DH_generate_parameters_ex() generates Diffie-Hellman parameters that can
26 be shared among a group of users, and stores them in the provided B<DH>
27 structure. The pseudo-random number generator must be
28 seeded prior to calling DH_generate_parameters().
30 B<prime_len> is the length in bits of the safe prime to be generated.
31 B<generator> is a small number E<gt> 1, typically 2 or 5.
33 A callback function may be used to provide feedback about the progress
34 of the key generation. If B<cb> is not B<NULL>, it will be
35 called as described in L<BN_generate_prime(3)> while a random prime
36 number is generated, and when a prime has been found, B<BN_GENCB_call(cb, 3, 0)>
37 is called. See L<BN_generate_prime(3)> for information on
38 the BN_GENCB_call() function.
40 DH_check() validates Diffie-Hellman parameters. It checks that B<p> is
41 a safe prime, and that B<g> is a suitable generator. In the case of an
42 error, the bit flags DH_CHECK_P_NOT_SAFE_PRIME or
43 DH_NOT_SUITABLE_GENERATOR are set in B<*codes>.
44 DH_UNABLE_TO_CHECK_GENERATOR is set if the generator cannot be
45 checked, i.e. it does not equal 2 or 5.
49 DH_generate_parameters_ex() and DH_check() return 1 if the check could be
50 performed, 0 otherwise.
52 DH_generate_parameters() (deprecated) returns a pointer to the DH structure, or
53 NULL if the parameter generation fails.
55 The error codes can be obtained by L<ERR_get_error(3)>.
59 DH_generate_parameters_ex() and DH_generate_parameters() may run for several
60 hours before finding a suitable prime.
62 The parameters generated by DH_generate_parameters_ex() and DH_generate_parameters()
63 are not to be used in signature schemes.
67 If B<generator> is not 2 or 5, B<dh-E<gt>g>=B<generator> is not
72 L<dh(3)>, L<ERR_get_error(3)>, L<rand(3)>,
77 Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
79 Licensed under the OpenSSL license (the "License"). You may not use
80 this file except in compliance with the License. You can obtain a copy
81 in the file LICENSE in the source distribution or at
82 L<https://www.openssl.org/source/license.html>.