Privacy and Nomadic Computing: A Public-Key Cryptosystem Based on Passwords

Frederic Prost (1) , Lydie Terras (2)

1 CAPP - Calculs algorithmes programmes et preuves
2 LIG - Laboratoire d'Informatique de Grenoble

The use of public-key cryptography is complicated in a nomadic computing era. Private keys are typically huge numbers that are impossible to memorize or even to write down and have to be stored electronically. Therefore a mobile user has somehow to keep its private key with him at all time (it is senseless to imagine that the private key is downloaded through a public network). It is neither realistic nor safe. Indeed the mobile device must be protected, which is usually done through password mechanisms. At the end of the day all the cryptosystem relies on this password. In this paper we propose a generic way to produce keys from a password using secure hashing functions. We have done an implementation of a nomadic PGP as a proof of concept: the software is a java applet, thus platform independent, providing a complete solution for mail encryption based on public-key cryptography. In the end the user just has to remember its password, and no longer has to rely on specific software/operating system/hardware settings.

Mots clés: Password; Public-key cryptography; Secure hashing functions; RSA; PGP

Domaines: Cryptographie et sécurité [cs.CR]

Frederic Prost, Lydie Terras. Privacy and Nomadic Computing: A Public-Key Cryptosystem Based on Passwords. 2013. ⟨hal-00933842⟩