Beta 1

Title Error-Tolerant Passphrases
Author Soinski, Andrzej
Supervisor Jensen, Christian D. (System Security, Department of Informatics and Mathematical Modeling, Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark)
Institution Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark
Thesis level Master's thesis
Year 2008
Abstract In this work, a modified implementation of secret-based authentication system has been proposed. The main aim was to design and implement a system tolerant towards typing errors. Therefore, based on data gathered in experiments, an algorithm capable of providing a metric of strings similarity has been developed. The metric was based on a concept of Levenshtein distance. The developed algorithm has been implemented and tested. The architecture of Pluggable Authentication Modules has been chosen as the base for the new authentication system. The aim of the design was to incorporate tolerance towards errors into one of the commonly used in Linux/UNIX environment PAM modules – pam_unix. The module has been extended to calculate similarity of the input provided by a user and the passphrase stored in the system beforehand. For purposes of matching the passphrase with the input, the passphrase has been securely stored with help of means provided by Trusted Platform Module. The sealing and unsealing operations have been used to provide secure and convenient way of storing the passphrase. The new error-tolerant authentication has been designed as an overlay to already existing authentication and activates itself only if the traditional authentication has failed. In performed simulations, the new system provided ability to significantly increase rate of successful authentications and thus shorten the time needed to authenticate successfully with a passphrase.
Series IMM-M.Sc.-2008-96
Original PDF ep08_96.pdf (7.99 MB)
Admin Creation date: 2008-10-09    Update date: 2008-10-09    Source: dtu    ID: 224344    Original MXD