Keep Passwords Away from Memory: Password Caching and Verification Using TPM

Abstract

TPM is able to provide strong secure storage for sensitive data such as passwords. Although several commercial password managers have used TPM to cache passwords, they are not capable of protecting passwords during verification. This paper proposes a new TPM-based password caching and verification method called PwdCaVe. In addition to using TPM in password caching, PwdCaVe also uses TPM during password verification. In PwdCaVe, all password-related computations are performed in the TPM. PwdCaVe guarantees that once a password is cached in the TPM, it will be protected by the TPM through the rest of its lifetime, thus eliminating the possibility that passwords might be attacked in memory. A prototype of PwdCaVe is implemented on Linux to demonstrate its feasibility.