| Information flow security is branch of computer science aimed at regulating of the dissemination of information in programs, that is, to preventing the inadvertent flow of private information handled by computer programs to unauthorized public entities.;Although static systems for programming language based information flow control are well-studied, few works address runtime security of information flow. Runtime information flow control offers distinct advantages in precision and in the ability to support dynamically defined policies. To this end, this thesis develops dynamic techniques to track direct and indirect flows of information, and secure information leaks due to timing channels, in higher-order programs.;We formulate two runtime information flow systems: lambda deps and lsyncseq . lambdadeps secures the direct and indirect flows in programs by tracking the dependencies between the values flowing across various program points, while lsyncseq decouples the publicly observable timing behavior of programs from secret data by synchronizing the execution times of timing-sensitive pieces of codes. Noninterference results are proved for all our systems. |
