Implementing Support for Pointers to Private Data in a General-Purpose Secure Multi-Party Compiler

摘要

Recent compilers allow a general-purpose program (written in a conventionalprogramming language) that handles private data to be translated into securedistributed implementation of the corresponding functionality. The resultingprogram is then guaranteed to provably protect private data using securemulti-party computation techniques. The goals of such compilers are generality,usability, and efficiency, but the complete set of features of a modernprogramming language has not been supported to date by the existing compilers.In particular, recent compilers PICCO and the two-party ANSI C compiler striveto translate any C program into its secure multi-party implementation, butcurrently lack support for pointers and dynamic memory allocation, which areimportant components of many C programs. In this work, we mitigate thelimitation and add support for pointers to private data and consequentlydynamic memory allocation to the PICCO compiler, enabling it to handle a morediverse set of programs over private data. Because doing so opens up a newdesign space, we investigate the use of pointers to private data (with known aswell as private locations stored in them) in programs and report our findings.Besides dynamic memory allocation, we examine other important topics associatedwith common pointer use such as reference by pointer/address, casting, andbuilding various data structures in the context of secure multi-partycomputation. This results in enabling the compiler to automatically translate auser program that uses pointers to private data into its distributedimplementation that provably protects private data throughout the computation.We empirically evaluate the constructions and report on performance ofrepresentative programs.