It remains an open problem to design a secure and efficient RSA-based password-authenticated key exchange(PAKE)protocol in the areas of cryptography.In 2011

Wei proposed the first provably secure gateway-oriented PAKE protocol using RSA

and claimed that the protocol is provably secure in the random oracle model based on the intractability of the integer factorization problem.However

in this short paper

we point out that an adversary can launch the separation attack on their protocol by exploiting the oracle service unwittingly provided by the server

and a user's password can thus be guessed just after tens of malicious sessions.Our cryptanalysis result invalidates Wei's claim that their protocol can achieve the security goal of password protection

and highlights the damaging threat that separation attack poses to RSA-based PAKE protocols.Furthermore

we uncover the flaws in their formal security proof and put forward an enhancement to overcome the identified defect.The analysis results show that the improved protocol eliminates the vulnerability of Wei's protocol while keeping the merit of high performance

suitable for mobile application scenarios.