EVP_SignFinal() signs the data in B<ctx> using the private key B<pkey> and
places the signature in B<sig>. B<sig> must be at least EVP_PKEY_size(pkey)
-bytes in size. B<s> is an OUT paramter, and not used as an IN parameter.
+bytes in size. B<s> is an OUT parameter, and not used as an IN parameter.
The number of bytes of data written (i.e. the length of the signature)
will be written to the integer at B<s>, at most EVP_PKEY_size(pkey) bytes
will be written.