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 int DH_generate_parameters_ex(DH *dh, int prime_len, int generator, BN_GENCB *cb);
17 int DH_check(DH *dh, int *codes);
18 int DH_check_params(DH *dh, int *codes);
20 int DH_check_ex(const DH *dh);
21 int DH_check_params_ex(const DH *dh);
22 int DH_check_pub_key_ex(const DH *dh, const BIGNUM *pub_key);
24 Deprecated since OpenSSL 0.9.8, can be hidden entirely by defining
25 B<OPENSSL_API_COMPAT> with a suitable version value, see
26 L<openssl_user_macros(7)>:
28 DH *DH_generate_parameters(int prime_len, int generator,
29 void (*callback)(int, int, void *), void *cb_arg);
33 DH_generate_parameters_ex() generates Diffie-Hellman parameters that can
34 be shared among a group of users, and stores them in the provided B<DH>
35 structure. The pseudo-random number generator must be
36 seeded before calling it.
37 The parameters generated by DH_generate_parameters_ex() should not be used in
40 B<prime_len> is the length in bits of the safe prime to be generated.
41 B<generator> is a small number E<gt> 1, typically 2 or 5.
43 A callback function may be used to provide feedback about the progress
44 of the key generation. If B<cb> is not B<NULL>, it will be
45 called as described in L<BN_generate_prime(3)> while a random prime
46 number is generated, and when a prime has been found, B<BN_GENCB_call(cb, 3, 0)>
47 is called. See L<BN_generate_prime_ex(3)> for information on
48 the BN_GENCB_call() function.
50 DH_generate_parameters() is similar to DH_generate_prime_ex() but
51 expects an old-style callback function; see
52 L<BN_generate_prime(3)> for information on the old-style callback.
54 DH_check_params() confirms that the B<p> and B<g> are likely enough to
56 This is a lightweight check, if a more thorough check is needed, use
58 The value of B<*codes> is updated with any problems found.
59 If B<*codes> is zero then no problems were found, otherwise the
60 following bits may be set:
64 =item DH_CHECK_P_NOT_PRIME
66 The parameter B<p> has been determined to not being an odd prime.
67 Note that the lack of this bit doesn't guarantee that B<p> is a
70 =item DH_NOT_SUITABLE_GENERATOR
72 The generator B<g> is not suitable.
73 Note that the lack of this bit doesn't guarantee that B<g> is
74 suitable, unless B<p> is known to be a strong prime.
76 =item DH_MODULUS_TOO_SMALL
78 The modulus is too small.
80 =item DH_MODULUS_TOO_LARGE
82 The modulus is too large.
86 DH_check() confirms that the Diffie-Hellman parameters B<dh> are valid. The
87 value of B<*codes> is updated with any problems found. If B<*codes> is zero then
88 no problems were found, otherwise the following bits may be set:
92 =item DH_CHECK_P_NOT_PRIME
94 The parameter B<p> is not prime.
96 =item DH_CHECK_P_NOT_SAFE_PRIME
98 The parameter B<p> is not a safe prime and no B<q> value is present.
100 =item DH_UNABLE_TO_CHECK_GENERATOR
102 The generator B<g> cannot be checked for suitability.
104 =item DH_NOT_SUITABLE_GENERATOR
106 The generator B<g> is not suitable.
108 =item DH_CHECK_Q_NOT_PRIME
110 The parameter B<q> is not prime.
112 =item DH_CHECK_INVALID_Q_VALUE
114 The parameter B<q> is invalid.
116 =item DH_CHECK_INVALID_J_VALUE
118 The parameter B<j> is invalid.
122 DH_check_ex(), DH_check_params() and DH_check_pub_key_ex() are similar to
123 DH_check() and DH_check_params() respectively, but the error reasons are added
124 to the thread's error queue instead of provided as return values from the
129 DH_generate_parameters_ex(), DH_check() and DH_check_params() return 1
130 if the check could be performed, 0 otherwise.
132 DH_generate_parameters() returns a pointer to the DH structure or NULL if
133 the parameter generation fails.
135 DH_check_ex(), DH_check_params() and DH_check_pub_key_ex() return 1 if the
136 check is successful, 0 for failed.
138 The error codes can be obtained by L<ERR_get_error(3)>.
142 L<DH_new(3)>, L<ERR_get_error(3)>, L<RAND_bytes(3)>,
147 DH_generate_parameters() was deprecated in OpenSSL 0.9.8; use
148 DH_generate_parameters_ex() instead.
152 Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
154 Licensed under the Apache License 2.0 (the "License"). You may not use
155 this file except in compliance with the License. You can obtain a copy
156 in the file LICENSE in the source distribution or at
157 L<https://www.openssl.org/source/license.html>.