Ensuring the Correctness of Lightweight Tactics for JavaCard Dynamic Logic

The interactive theorem prover developed in the KeY project, which implements a sequent calculus for JavaCard Dynamic Logic (JavaCardDL) is based on taclets. Taclets are lightweight tactics with easy to master syntax and semantics. Adding new taclets to the calculus is quite simple, but poses correctness problems. We present an approach how derived (non-axiomatic) taclets for JavaCardDL can be proven sound in JavaCardDL itself. Together with proof management facilities, our concept allows the safe introduction of new derived taclets while preserving the soundness of the calculus.