Mobile device assisted secure computer network communications embodiments are presented that employ a mobile device (e.g., a mobile phone, personal digital assistant (PDA), and the like) to assist in user authentication. In general, this is accomplished by having a user enter a password into a client computer which is in contact with a server associated with a secure Web site. This password is integrated with a secret value, which is generated in real time by the mobile device. The secret value is bound to both the mobile device's hardware and the secure Web site being accessed, such that it is unique to both. In this way, a different secret value is generated for each secure Web site accessed, and another user cannot impersonate the user and log into a secure Web site unless he or she knows the password and possesses the user's mobile device simultaneously.

Mobile device assisted secure computer network communications

This paper considers the problem of password-authenticated key exchange (PAKE) in a client-server setting, where the server authenticates using a stored password file, and it is desirable to maintain some degree of security even if the server is compromised A PAKE scheme is said to be resilient to server compromise if an adversary who compromises the server must at least perform an offline dictionary attack to gain any advantage in impersonating a client (Of course, offline dictionary attacks should be infeasible in the absence of server compromise) One can see that this is the best security possible, since by definition the password file has enough information to allow one to play the role of the server, and thus to verify passwords in an offline dictionary attack

While some previous PAKE schemes have been proven resilient to server compromise, there was no known general technique to take an arbitrary PAKE scheme and make it provably resilient to server compromise This paper presents a practical technique for doing so which requires essentially one extra round of communication and one signature computation/ verification We prove security in the universal composability framework by (1) defining a new functionality for PAKE with resilience to server compromise, (2) specifying a protocol combining this technique with a (basic) PAKE functionality, and (3) proving (in the random oracle model) that this protocol securely realizes the new functionality

/pdf/a-method-for-making-password-based-key-exchange-resilient-to-3t8a23a3rn.pdf

A method for making password-based key exchange resilient to server compromise

It is well understood that passwords must be very long and complex to have sufficient entropy for security purposes. Unfortunately, these passwords tend to be hard to memorize, and so alternatives are sought. Smart Cards, Biometrics, and Reverse Turing Tests (human-only solvable puzzles) are options, but another option is to use pass-phrases. This paper explores methods for making passphrases suitable for use with password-based authentication and key-exchange (PAKE) protocols, and in particular, with schemes resilient to server-file compromise. In particular, the Ω-method of Gentry, MacKenzie and Ramzan, is combined with the Bellovin-Merritt protocol to provide mutual authentication (in the random oracle model (Canetti, Goldreich & Halevi 2004, Bellare, Boldyreva & Palacio 2004, Maurer, Renner & Holenstein 2004)). Furthermore, since common password-related problems are typographical errors, and the CAPSLOCK key, we show how a dictionary can be used with the DamerauLevenshtein string-edit distance metric to construct a case-insensitive pass-phrase system that can tolerate zero, one, or two spelling-errors per word, with no loss in security. Furthermore, we show that the system can be made to accept pass-phrases that have been arbitrarily reordered, with a security cost that can be calculated. While a pass-phrase space of 2 is not achieved by this scheme, sizes in the range of 2 to 2 result from various selections of parameter sizes. An attacker who has acquired the server-file must exhaust over this space, while an attacker without the serverfile cannot succeed with non-negligible probability.

/pdf/spelling-error-tolerant-order-independent-pass-phrases-via-45gcnmv7p6.pdf

Spelling-Error Tolerant, Order-Independent Pass-Phrases via the Damerau-Levenshtein String-Edit Distance Metric.

It is well understood that passwords must be very long and complex to have sufficient entropy for security purposes. Unfortunately, these passwords tend to be hard to memorize, and so alternatives are sought. Smart Cards, Biometrics, and Reverse Turing Tests (human-only solvable puzzles) are options, but another option is to use pass-phrases.

This paper explores methods for making pass-phrases suitable for use with password-based authentication and key-exchange (PAKE) protocols, and in particular, with schemes resilient to server-file compromise. In particular, the Ω-method of Gentry, MacKenzie and Ramzan, is combined with the Bellovin-Merritt protocol to provide mutual authentication (in the random oracle model (Canetti, Goldreich & Halevi 2004, Bellare, Boldyreva & Palacio 2004, Maurer, Renner & Holenstein 2004)). Furthermore, since common password-related problems are typographical errors, and the CAPSLOCK key, we show how a dictionary can be used with the Damerau-Levenshtein string-edit distance metric to construct a case-insensitive pass-phrase system that can tolerate zero, one, or two spelling-errors per word, with no loss in security. Furthermore, we show that the system can be made to accept pass-phrases that have been arbitrarily reordered, with a security cost that can be calculated.

While a pass-phrase space of 2128 is not achieved by this scheme, sizes in the range of 252 to 2112 result from various selections of parameter sizes. An attacker who has acquired the server-file must exhaust over this space, while an attacker without the server-file cannot succeed with non-negligible probability.

Spelling-error tolerant, order-independent pass-phrases via the damerau-levenshtein string-edit distance metric

Security weakness in a three-party pairing-based protocol for password authenticated key exchange

We investigate efficient protocols for password-authenticated key exchange based on the RSA public-key cryptosystem. To date, most of the published protocols for password-authenticated key exchange were based on Diffie-Hellman key exchange. It seems difficult to design efficient password-authenticated key exchange protocols using RSA and other public-key cryptographic techniques. In fact, many of the proposed protocols for password-authenticated key exchange based on RSA have been shown to be insecure; the only one that remains secure is the SNAPI protocol. Unfortunately, the SNAPI protocol has to use a prime public exponent e larger than the RSA modulus n. In this paper, we present a new password-authenticated key exchange protocol, called PEKEP, which allows using both large and small prime numbers as RSA public exponent. Based on number-theoretic techniques, we show that the new protocol is secure against the e-residue attack, a special type of off-line dictionary attack against RSA-based password-authenticated key exchange protocols. We also provide a formal security analysis of PEKEP under the RSA assumption and the random oracle model. On the basis of PEKEP, we present a computationally-efficient key exchange protocol to mitigate the burden on communication entities.

/pdf/new-approaches-to-password-authenticated-key-exchange-based-2ukplvi98h.pdf

Muxiang Zhang

Papers

New Approaches to Password Authenticated Key Exchange Based on RSA

New Approaches to Password Authenticated Key Exchange based on RSA.

New approaches to password authenticated key exchange based on RSA