Document removal of digest+signature algorithm link.

algorithms respectively. The associated signature algorithm is RSA in each case.

EVP_dss() and EVP_dss1() return B<EVP_MD> structures for SHA and SHA1 digest

algorithms but using DSS (DSA) for the signature algorithm.

algorithms but using DSS (DSA) for the signature algorithm. Note: there is 

no need to use these pseudo-digests in OpenSSL 1.0.0 and later, they are

however retained for compatibility.

EVP_md_null() is a "null" message digest that does nothing: i.e. the hash it

returns is of zero length.

 printf("\n");

 }

=head1 BUGS

The link between digests and signing algorithms results in a situation where

EVP_sha1() must be used with RSA and EVP_dss1() must be used with DSS

even though they are identical digests.

=head1 SEE ALSO

L<evp(3)|evp(3)>, L<hmac(3)|hmac(3)>, L<md2(3)|md2(3)>,

EVP_dss(), EVP_dss1(), EVP_mdc2() and EVP_ripemd160() were

changed to return truely const EVP_MD * in OpenSSL 0.9.7.

The link between digests and signing algorithms was fixed in OpenSSL 1.0 and

later, so now EVP_sha1() can be used with RSA and DSA, there is no need to

use EVP_dss1() any more.

OpenSSL 1.0 and later does not include the MD2 digest algorithm in the

default configuration due to its security weaknesses.

=cut