HTW Berlin Fachbereich 4 Internationaler Studiengang Internationale Medieninformatik (Bachelor) Aktuelles - Medien: Kryptographie Winter Term 2009/10

Lab 11: ElGamal

1. Why can the signature value b be calculated at all in the ElGamal-Protocol?
2. Why does the verification work?
3. Why does the decryption work?
4. What is the connection between ElGamal and Diffie-Hellmann Key Exchange?
5. (For the bored) It is easy to make errors while signing, especially if k can be discovered. If Eve knows k, how can she calculate x? If Eve has two messages that Alice signed with the same value of k, can she calculate x?

This material is jointly prepared by Dr. Hermann Thiel and Prof. Dr. Debora Weber-Wulff. Much of the material comes from other sources and is denoted by the copyright notices on the individual pages