Add signature attack tests
Add signature attack tests

AMarcedone/keytransparency,alsophian/keytransparency,google/keytransparency,google/keytransparency,gdbelvin/keytransparency,gdbelvin/keytransparency,alsophian/keytransparency,cesarghali/keytransparency,AMarcedone/keytransparency,cesarghali/keytransparency