Commit eeb21772 authored by Matt Caswell's avatar Matt Caswell
Browse files

Add dhparam sanity check and update DH_check documentation 



The -check argument to dhparam should never identify any problems if we
have just generated the parameters. Add a sanity check for this and print
an error and fail if necessary.

Also updates the documentation for the -check argument, and the DH_check()
function.

RT#4244

Reviewed-by: default avatarRichard Levitte <levitte@openssl.org>
parent b2b361f6

apps/dhparam.c

+20 −5
Original line number Diff line number Diff line
@@ -270,15 +270,30 @@ int dhparam_main(int argc, char **argv) 
            goto end;

        }

        if (i & DH_CHECK_P_NOT_PRIME)

            printf("p value is not prime\n");

            BIO_printf(bio_err, "WARNING: p value is not prime\n");

        if (i & DH_CHECK_P_NOT_SAFE_PRIME)

            printf("p value is not a safe prime\n");

            BIO_printf(bio_err, "WARNING: p value is not a safe prime\n");

        if (i & DH_CHECK_Q_NOT_PRIME)

            BIO_printf(bio_err, "WARNING: q value is not a prime\n");

        if (i & DH_CHECK_INVALID_Q_VALUE)

            BIO_printf(bio_err, "WARNING: q value is invalid\n");

        if (i & DH_CHECK_INVALID_J_VALUE)

            BIO_printf(bio_err, "WARNING: j value is invalid\n");

        if (i & DH_UNABLE_TO_CHECK_GENERATOR)

            printf("unable to check the generator value\n");

            BIO_printf(bio_err,

                       "WARNING: unable to check the generator value\n");

        if (i & DH_NOT_SUITABLE_GENERATOR)

            printf("the g value is not a generator\n");

            BIO_printf(bio_err, "WARNING: the g value is not a generator\n");

        if (i == 0)

            printf("DH parameters appear to be ok.\n");

            BIO_printf(bio_err, "DH parameters appear to be ok.\n");

        if (num != 0 && i != 0) {

            /*

             * We have generated parameters but DH_check() indicates they are

             * invalid! This should never happen!

             */

            BIO_printf(bio_err, "ERROR: Invalid parameters generated\n");

            goto end;

        }

    }

    if (C) {

        unsigned char *data;

doc/apps/dhparam.pod

+2 −1
Original line number Diff line number Diff line
@@ -72,7 +72,8 @@ avoid small-subgroup attacks that may be possible otherwise. 


=item B<-check>



check if the parameters are valid primes and generator.

Performs numerous checks to see if the supplied parameters are valid and

displays a warning if not.



=item B<-2>, B<-5>

doc/crypto/DH_generate_parameters.pod

+35 −11
Original line number Diff line number Diff line
@@ -37,12 +37,41 @@ number is generated, and when a prime has been found, B<BN_GENCB_call(cb, 3, 0)> 
is called. See L<BN_generate_prime(3)> for information on

the BN_GENCB_call() function.



DH_check() validates Diffie-Hellman parameters. It checks that B<p> is

a safe prime, and that B<g> is a suitable generator. In the case of an

error, the bit flags DH_CHECK_P_NOT_SAFE_PRIME or

DH_NOT_SUITABLE_GENERATOR are set in B<*codes>.

DH_UNABLE_TO_CHECK_GENERATOR is set if the generator cannot be

checked, i.e. it does not equal 2 or 5.

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:



=over 4



=item DH_CHECK_P_NOT_PRIME



The parameter B<p> is not prime.



=item DH_CHECK_P_NOT_SAFE_PRIME



The parameter B<p> is not a safe prime and no B<q> value is present.



=item DH_UNABLE_TO_CHECK_GENERATOR



The generator B<g> cannot be checked for suitability.



=item DH_NOT_SUITABLE_GENERATOR



The generator B<g> is not suitable.



=item DH_CHECK_Q_NOT_PRIME



The parameter B<q> is not prime.



=item DH_CHECK_INVALID_Q_VALUE



The parameter B<q> is invalid.



=item DH_CHECK_INVALID_J_VALUE



The parameter B<j> is invalid.



=back



=head1 RETURN VALUES
@@ -62,11 +91,6 @@ 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 BUGS



If B<generator> is not 2 or 5, B<dh-E<gt>g>=B<generator> is not

a usable generator.



=head1 SEE ALSO



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