Document DH_check_params()

=head1 NAME

DH_generate_parameters_ex, DH_generate_parameters,

DH_check - generate and check Diffie-Hellman parameters

DH_check, DH_check_params - generate and check Diffie-Hellman

parameters

=head1 SYNOPSIS

 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:

is called. See L<BN_generate_prime(3)> for information on

the BN_GENCB_call() function.

DH_check_params() confirms that the B<p> and B<g> 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<p> has been determined to not being an odd prime.

Note that the lack of this bit doesn't guarantee that B<p> is a

prime.

=item DH_NOT_SUITABLE_GENERATOR

The generator B<g> is not suitable.

Note that the lack of this bit doesn't guarantee that B<g> is

suitable, unless B<p> is known to be a strong prime.

=back

DH_check() confirms that the Diffie-Hellman parameters B<dh> 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:

=head1 RETURN VALUES

DH_generate_parameters_ex() and DH_check() return 1 if the check could be

performed, 0 otherwise.

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.

=head1 SEE ALSO

L<dh(3)>, L<ERR_get_error(3)>, L<rand(3)>,

L<DH_new(3)>, L<ERR_get_error(3)>, L<RAND_bytes(3)>,

L<DH_free(3)>

=head1 COPYRIGHT