Verifier-based anonymous password-authenticated key exchange protocol in the standard model

Anonymous password-authenticated key exchange (APAKE) allows a client to authenticate herself and to establish a secure session key with a remote server via only a low-entropy password, while keeping her actual identity anonymous to the third party as well as to the server. Since that APAKE protocol enjoys both the convenience of password authentication and the advantage of privacy protection, researchers have paid much attention to them. However, most of the existing APAKE protocols are designed in the symmetric setting which does not take into consideration the threat of password file leakage. To mitigate the damage of server compromise, we propose a verifier-based anonymous password-authenticated key exchange protocol, in which the server holds a verifier corresponding to each client instead of the clear password. The construction of our protocol is built on standard cryptographic primitives such public key encryption, smooth projective hash functions and password hashing schemes. The resulting protocol is proved secure in the standard model, i.e., without resorting to random oracles. Comparisons with other similar schemes show that our protocol guarantees stronger security while enjoys considerable efficiency in terms of computational cost.