In a two-server PAKE protocol, a client divides its password into two shares, enabling secure authentication without revealing the password. This paper introduces compilers that transform two-party PAKE protocols into two-server ID2S PAKE protocols with implicit authentication. These ID2S PAKE protocols maintain security without random oracles, offering a computational efficiency advantage over Katz et al.’s two-server PAKE protocol with similar security guarantees.

• Information Security
• Password Authentication
• Two-Server Authentication

Secure password storage is a vital aspect in systems based on password authentication, which is still the most widely used authentication technique, despite some security flaws. the hashed password is converted into a negative password. Moreover, there are lots of corresponding ENPs for a given plain password, which makes precomputation attacks (e.g., lookup table attack and rainbow table attack) infeasible. The algorithm complexity analyses and comparisons show that the ENP could resist lookup table attack and provide stronger password protection under dictionary attack. It is worth mentioning that the ENP does not introduce extra elements (e.g., salt); besides this, the ENP could still resist precomputation attacks. Most importantly, the ENP is the first password protection scheme that combines the cryptographic hash function, the negative password, and the symmetric-key algorithm, without the need for additional information except the plain password.

• Hashed Password Protection
• Password Authentication
• Password Security