=head1 DESCRIPTION
RSA_sign() signs the message digest B<m> of size B<m_len> using the
-private key B<rsa> as specified in PKCS #1 v2.0. It stores the
-signature in B<sigret> and the signature size in B<siglen>. B<sigret>
-must point to RSA_size(B<rsa>) bytes of memory.
+private key B<rsa> using RSASSA-PKCS1-v1_5 as specified in RFC 3447. It
+stores the signature in B<sigret> and the signature size in B<siglen>.
+B<sigret> must point to RSA_size(B<rsa>) bytes of memory.
Note that PKCS #1 adds meta-data, placing limits on the size of the
key that can be used.
See L<RSA_private_encrypt(3)> for lower-level