Security-by-Contract: Toward a Semantics for Digital Signatures on Mobile Code

In this paper we propose the notion of security-by-contract, a mobile contract that an application carries with itself. The key idea of the framework is that a digital signature should not just certify the origin of the code but rather bind together the code with a contract. We provide a description of the overall life-cycle of mobile code in the setting of security-by-contract, describe a tentative structure for a contractual language and propose a number of algorithms for one of the key steps in the process, the contract-policy matching issue. We argue that security-by-contract would provide a semantics for digital signatures on mobile code thus being a step in the transition from trusted code to trustworthy code. © Springer-Verlag Berlin Heidelberg 2007.