AugSSO: Secure Threshold Single-Sign-On Authentication With Popular Password Collection

Single-sign-on authentication is widely deployed in mobile systems, which allows an identity server to authenticate a mobile user and issue her/him with a token, such that the user can access diverse mobile services. To address the single-point-of-failure problem, threshold single-sign-on authentication (PbTA) is a feasible solution, where multiple identity servers perform user authentication and token issuance in a threshold way. However, existing PbTA schemes confront critical drawbacks. Specifically, these schemes are vulnerable to perpetual secret leakage attacks (PSLA): an adversary perpetually compromises secrets of identity servers (e.g., secret key shares or credentials) to break security. Besides, they fail to achieve popular password collection, which is an effective means of enhancing system security. In this paper, we propose a secure PbTA scheme with popular password collection, dubbed AugSSO. In AugSSO, we conceive an efficient key renewal mechanism that allows identity servers to periodically update secret key shares in batches, and require storage of hardened password-derived public keys in credentials for user authentication, thereby resisting PSLA. We also present a popular password collection mechanism, where an aggregation server is introduced to identify popular passwords without disclosing unpopular ones. We provide security analysis and performance evaluation to demonstrate security and efficiency of AugSSO.