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Client-Server Password Recovery

Author: Chmielewski, L. · Hoepman, J.H. · Rossum, P. van
Institution: TNO Informatie- en Communicatietechnologie
Source:Arxiv preprint arXiv:0906.4668
Identifier: 462451
Keywords: Password recovery · Threshold encryption scheme · Private computing · Personal entropy


Human memory is not perfect – people constantly memorize new facts and forget old ones. One example is forgetting a password, a common problem raised at IT help desks. We present several protocols that allow a user to automatically recover a password from a server using partial knowledge of the password. These protocols can be easily adapted to the personal entropy setting [7], where a user can recover a password only if he can answer a large enough subset of personal questions. We introduce client-server password recovery methods, in which the recovery data are stored at the server, and the recovery procedures are integrated into the login procedures. These methods apply to two of the most common types of password based authentication systems. The security of these solutions is significantly better than the security of presently proposed password recovery schemes. Our protocols are based on a variation of threshold encryption [5,8,17] that may be of independent interest.