A mechanism for patching ROM smart card

Traditional smart card patch is processed in the place where main command accepts. This patching method has the shortcomings of low efficiency and long time to execute. The paper proposes a new mechanism for patching ROM smart card APDU commands. The user can patch instructions for APDU commands according to their needs and redesigned APDU commands. It will go to the new designed instruction to execute from an already well masked ROM program. Then new demanded functions are implemented. The method solves the problem of patching functions on masked ROM card.