1=pod 2 3=head1 NAME 4 5DH_generate_parameters_ex, DH_generate_parameters, 6DH_check, DH_check_params, 7DH_check_ex, DH_check_params_ex, DH_check_pub_key_ex 8- generate and check Diffie-Hellman 9parameters 10 11=head1 SYNOPSIS 12 13 #include <openssl/dh.h> 14 15The following functions have been deprecated since OpenSSL 3.0, and can be 16hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value, 17see L<openssl_user_macros(7)>: 18 19 int DH_generate_parameters_ex(DH *dh, int prime_len, int generator, BN_GENCB *cb); 20 21 int DH_check(DH *dh, int *codes); 22 int DH_check_params(DH *dh, int *codes); 23 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); 27 28The following functions have been deprecated since OpenSSL 0.9.8, and can be 29hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value, 30see L<openssl_user_macros(7)>: 31 32 DH *DH_generate_parameters(int prime_len, int generator, 33 void (*callback)(int, int, void *), void *cb_arg); 34 35=head1 DESCRIPTION 36 37All of the functions described on this page are deprecated. 38Applications should instead use L<EVP_PKEY_check(3)>, 39L<EVP_PKEY_public_check(3)>, L<EVP_PKEY_private_check(3)> and 40L<EVP_PKEY_param_check(3)>. 41 42DH_generate_parameters_ex() generates Diffie-Hellman parameters that can 43be shared among a group of users, and stores them in the provided B<DH> 44structure. The pseudo-random number generator must be 45seeded before calling it. 46The parameters generated by DH_generate_parameters_ex() should not be used in 47signature schemes. 48 49B<prime_len> is the length in bits of the safe prime to be generated. 50B<generator> is a small number E<gt> 1, typically 2 or 5. 51 52A callback function may be used to provide feedback about the progress 53of the key generation. If B<cb> is not B<NULL>, it will be 54called as described in L<BN_generate_prime(3)> while a random prime 55number is generated, and when a prime has been found, B<BN_GENCB_call(cb, 3, 0)> 56is called. See L<BN_generate_prime_ex(3)> for information on 57the BN_GENCB_call() function. 58 59DH_generate_parameters() is similar to DH_generate_prime_ex() but 60expects an old-style callback function; see 61L<BN_generate_prime(3)> for information on the old-style callback. 62 63DH_check_params() confirms that the B<p> and B<g> are likely enough to 64be valid. 65This is a lightweight check, if a more thorough check is needed, use 66DH_check(). 67The value of B<*codes> is updated with any problems found. 68If B<*codes> is zero then no problems were found, otherwise the 69following bits may be set: 70 71=over 4 72 73=item DH_CHECK_P_NOT_PRIME 74 75The parameter B<p> has been determined to not being an odd prime. 76Note that the lack of this bit doesn't guarantee that B<p> is a 77prime. 78 79=item DH_NOT_SUITABLE_GENERATOR 80 81The generator B<g> is not suitable. 82Note that the lack of this bit doesn't guarantee that B<g> is 83suitable, unless B<p> is known to be a strong prime. 84 85=item DH_MODULUS_TOO_SMALL 86 87The modulus is too small. 88 89=item DH_MODULUS_TOO_LARGE 90 91The modulus is too large. 92 93=back 94 95DH_check() confirms that the Diffie-Hellman parameters B<dh> are valid. The 96value of B<*codes> is updated with any problems found. If B<*codes> is zero then 97no problems were found, otherwise the following bits may be set: 98 99=over 4 100 101=item DH_CHECK_P_NOT_PRIME 102 103The parameter B<p> is not prime. 104 105=item DH_CHECK_P_NOT_SAFE_PRIME 106 107The parameter B<p> is not a safe prime and no B<q> value is present. 108 109=item DH_UNABLE_TO_CHECK_GENERATOR 110 111The generator B<g> cannot be checked for suitability. 112 113=item DH_NOT_SUITABLE_GENERATOR 114 115The generator B<g> is not suitable. 116 117=item DH_CHECK_Q_NOT_PRIME 118 119The parameter B<q> is not prime. 120 121=item DH_CHECK_INVALID_Q_VALUE 122 123The parameter B<q> is invalid. 124 125=item DH_CHECK_INVALID_J_VALUE 126 127The parameter B<j> is invalid. 128 129=back 130 131If 0 is returned or B<*codes> is set to a nonzero value the supplied 132parameters should not be used for Diffie-Hellman operations otherwise 133the security properties of the key exchange are not guaranteed. 134 135DH_check_ex(), DH_check_params() and DH_check_pub_key_ex() are similar to 136DH_check() and DH_check_params() respectively, but the error reasons are added 137to the thread's error queue instead of provided as return values from the 138function. 139 140=head1 RETURN VALUES 141 142DH_generate_parameters_ex(), DH_check() and DH_check_params() return 1 143if the check could be performed, 0 otherwise. 144 145DH_generate_parameters() returns a pointer to the DH structure or NULL if 146the parameter generation fails. 147 148DH_check_ex(), DH_check_params() and DH_check_pub_key_ex() return 1 if the 149check is successful, 0 for failed. 150 151The error codes can be obtained by L<ERR_get_error(3)>. 152 153=head1 SEE ALSO 154 155L<DH_new(3)>, L<ERR_get_error(3)>, L<RAND_bytes(3)>, 156L<DH_free(3)> 157 158=head1 HISTORY 159 160All of these functions were deprecated in OpenSSL 3.0. 161 162DH_generate_parameters() was deprecated in OpenSSL 0.9.8; use 163DH_generate_parameters_ex() instead. 164 165=head1 COPYRIGHT 166 167Copyright 2000-2023 The OpenSSL Project Authors. All Rights Reserved. 168 169Licensed under the Apache License 2.0 (the "License"). You may not use 170this file except in compliance with the License. You can obtain a copy 171in the file LICENSE in the source distribution or at 172L<https://www.openssl.org/source/license.html>. 173 174=cut 175