question: public boolean verifyToken ( String data , String signature ) { if ( signature . length ( ) == 0 ) { return false ; } try { return signingKey . verify ( data , signature ) ; } catch ( KeyczarException e ) { return false ; } }
target:  Returns true if signature is valid for data, using the signing key. Keyczar throws exceptions for many cases of malformed signatures, but this instead returns false.