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 131DH_check_ex(), DH_check_params() and DH_check_pub_key_ex() are similar to 132DH_check() and DH_check_params() respectively, but the error reasons are added 133to the thread's error queue instead of provided as return values from the 134function. 135 136=head1 RETURN VALUES 137 138DH_generate_parameters_ex(), DH_check() and DH_check_params() return 1 139if the check could be performed, 0 otherwise. 140 141DH_generate_parameters() returns a pointer to the DH structure or NULL if 142the parameter generation fails. 143 144DH_check_ex(), DH_check_params() and DH_check_pub_key_ex() return 1 if the 145check is successful, 0 for failed. 146 147The error codes can be obtained by L<ERR_get_error(3)>. 148 149=head1 SEE ALSO 150 151L<DH_new(3)>, L<ERR_get_error(3)>, L<RAND_bytes(3)>, 152L<DH_free(3)> 153 154=head1 HISTORY 155 156All of these functions were deprecated in OpenSSL 3.0. 157 158DH_generate_parameters() was deprecated in OpenSSL 0.9.8; use 159DH_generate_parameters_ex() instead. 160 161=head1 COPYRIGHT 162 163Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved. 164 165Licensed under the Apache License 2.0 (the "License"). You may not use 166this file except in compliance with the License. You can obtain a copy 167in the file LICENSE in the source distribution or at 168L<https://www.openssl.org/source/license.html>. 169 170=cut 171