Password-based Key Exchange Research Articles

Enhanced password-based simple three-party key exchange protocol

Recently, Lu and Cao proposed a simple three-party password-based key exchange (STPKE) protocol based on the CCDH assumption. They claimed that their protocol is secure, efficient, and practical. In this paper, unlike their claims, we find that the STPKE protocol is still vulnerable to undetectable on-line password guessing attacks by using formal description, BPR model. These weakness is due to the fact that the messages of the communicants are not appropriately encrypted into the exchanged cryptographic messages. To enhance the security of the STPKE protocol, we suggest a countermeasure to resist our described attacks while the merits of the original protocol are left unchanged.

Fficient and Provably Secure Generic Construction of Client-to-Client Password-Based Key Exchange Protocol

Client-to-client password authenticated key exchange (C2C-PAKE) protocol enables two clients who only share their passwords with their own servers to establish a shared key for their secure communications. Recently, Byun et al. and Yin-Li respectively proposed first provably secure C2C-PAKE protocols. However, both protocols are found to be vulnerable to undetectable online dictionary attacks and other attacks. In this paper, we present an efficient generic construction for cross-realm C2C-PAKE protocols and prove its security in the Random-or-Real model due to Abdalla et al., without making use of the Random Oracle model.

Practical encrypted key agreement using passwords

We presented a simple and efficient password-based encrypted key exchange protocol that allows a user to establish secure session keys with remote servers from client terminals in low resource environments. He does not need to carry smart card storing his private information but just needs to know his identity and password. For this purpose, the scheme was implemented over elliptic curves because of their well-known advantages with regard to processing and size constraints. Furthermore, the scheme is provably secure under the assumptions that the hash function closely behaves like a random oracle and that the elliptic curve computational Diffie-Hellman problem is difficult.

Trapdoor Hard-to-Invert Group Isomorphisms and Their Application to Password-Based Authentication

In the security chain the weakest link is definitely the human one: human beings cannot remember long secrets and often resort to rather insecure solutions to keep track of their passwords or pass-phrases. For this reason it is very desirable to have protocols that do not require long passwords to guarantee security, even in the case in which exhaustive search is feasible. This is actually the goal of password-based key exchange protocols, secure against off-line dictionary attacks: two people share a password (possibly a very small one, say a 4-digit number), and after the protocol execution, they end up sharing a large secret session key (known to both of them, but nobody else). Then an adversary attacking the system should try several connections (on average 5000 for the above short password) in order to be able to get the correct password. Such a large number of erroneous connections can be prevented by various means. Our results can be highlighted as follows. First we define a new primitive that we call trapdoor hard-to-invert group isomorphisms, and give some candidates. Then we present a generic password-based key exchange construction that admits a security proof assuming that these objects exist. Finally, we instantiate our general scheme with some concrete examples, such as the Diffie-Hellman function and the RSA function, but more interestingly the modular square-root function, which leads to the first scheme with security related to the integer factorization problem. Furthermore, the latter variant is very efficient for one party (the server). Our results hold in the random-oracle model.