8 #ifndef BOTAN_KEYED_FILTER_H__     9 #define BOTAN_KEYED_FILTER_H__    11 #include <botan/filter.h>    12 #include <botan/sym_algo.h>    41       virtual bool valid_keylength(
size_t length) 
const = 0;
    49          { 
return (length == 0); }
 
virtual bool valid_iv_length(size_t length) const