A portable virtual machine target for proof-carrying code
Virtual machines and proof-carrying code provide two techniques that have been used independently to provide safety for mobile code. Both these techniques have strengths and limitations. Existing virtual machines, such as the Java VM, have several drawbacks. First, the effort required for safety verification is considerable. Second, and more subtly, the need to provide such verification by the code consumer inhibits the amount of optimization that can be performed by the code producer. This in turn makes just-in-time compilation surprisingly expensive. Proof-carrying code, on the other hand, has its own set of limitations, among which are the size of proofs and the fact that the certified code is no longer machine independent. By combining the two techniques, we are able to overcome these limitations. Our hybrid safe-code solution uses a virtual machine that has been designed specifically to support proof-carrying code, while simultaneously providing efficient just-in-time compilation and target-machine independence. In particular, our approach reduces the complexity of the required proofs, resulting in fewer proof obligations that need to be discharged at the target machine. (c) 2005 Elsevier B.V. All rights reserved.
virtual machines proof-carrying code safe mobile code dynamic (just-in-time) compilation