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