=pod =head1 NAME DH_generate_parameters_ex, DH_generate_parameters, DH_check, DH_check_params - generate and check Diffie-Hellman parameters =head1 SYNOPSIS #include int DH_generate_parameters_ex(DH *dh, int prime_len, int generator, BN_GENCB *cb); int DH_check(DH *dh, int *codes); int DH_check_params(DH *dh, int *codes); Deprecated: #if OPENSSL_API_COMPAT < 0x00908000L DH *DH_generate_parameters(int prime_len, int generator, void (*callback)(int, int, void *), void *cb_arg); #endif =head1 DESCRIPTION DH_generate_parameters_ex() generates Diffie-Hellman parameters that can be shared among a group of users, and stores them in the provided B structure. The pseudo-random number generator must be seeded prior to calling DH_generate_parameters(). B is the length in bits of the safe prime to be generated. B is a small number E 1, typically 2 or 5. A callback function may be used to provide feedback about the progress of the key generation. If B is not B, it will be called as described in L while a random prime number is generated, and when a prime has been found, B is called. See L for information on the BN_GENCB_call() function. DH_check_params() confirms that the B

and B are likely enough to be valid. This is a lightweight check, if a more thorough check is needed, use DH_check(). The value of B<*codes> is updated with any problems found. If B<*codes> is zero then no problems were found, otherwise the following bits may be set: =over 4 =item DH_CHECK_P_NOT_PRIME The parameter B

has been determined to not being an odd prime. Note that the lack of this bit doesn't guarantee that B

is a prime. =item DH_NOT_SUITABLE_GENERATOR The generator B is not suitable. Note that the lack of this bit doesn't guarantee that B is suitable, unless B

is known to be a strong prime. =back DH_check() confirms that the Diffie-Hellman parameters B are valid. The value of B<*codes> is updated with any problems found. If B<*codes> is zero then no problems were found, otherwise the following bits may be set: =over 4 =item DH_CHECK_P_NOT_PRIME The parameter B

is not prime. =item DH_CHECK_P_NOT_SAFE_PRIME The parameter B

is not a safe prime and no B value is present. =item DH_UNABLE_TO_CHECK_GENERATOR The generator B cannot be checked for suitability. =item DH_NOT_SUITABLE_GENERATOR The generator B is not suitable. =item DH_CHECK_Q_NOT_PRIME The parameter B is not prime. =item DH_CHECK_INVALID_Q_VALUE The parameter B is invalid. =item DH_CHECK_INVALID_J_VALUE The parameter B is invalid. =back =head1 RETURN VALUES DH_generate_parameters_ex(), DH_check() and DH_check_params() return 1 if the check could be performed, 0 otherwise. DH_generate_parameters() (deprecated) returns a pointer to the DH structure, or NULL if the parameter generation fails. The error codes can be obtained by L. =head1 NOTES DH_generate_parameters_ex() and DH_generate_parameters() may run for several hours before finding a suitable prime. The parameters generated by DH_generate_parameters_ex() and DH_generate_parameters() are not to be used in signature schemes. =head1 SEE ALSO L, L, L, L =head1 COPYRIGHT Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved. Licensed under the OpenSSL license (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at L. =cut