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cosec >students >Teaching >IPEC Winter 2008 

Stream Ciphers

Responsible

Joachim von zur Gathen

Lecture

Laila El Aimani

Time & Place

Start: Monday 17 March at 9.00 in the b-it Rheinsaal.

Contents

Stream ciphers constitute an important class of secret-key encryption algorithms. In fact, LFSR-based stream ciphers are widely used in many applications
because of the advantages they present compared to other encryption schemes, for instance, block ciphers: they are faster, require less hardware circuitry
and have fewer propagation errors. An example is Bluetooth encryption.

Stream ciphers consist of a seed, corresponding to the shared secret key, and a pseudorandom generator, which consists of constituent LFSRs and a nonlinear combination function. The result is a pseudo-random binary sequence, called the keystream, which is, in the case of  a binary additive stream cipher, bitwise added to the plaintext in order to obtain the ciphertext. Hence, attacks on stream ciphers have as ultimate goal the recovery of theinitializations of the LFSRs.

Topics include

Course Material

Literature

Allocation

Equivalent  2+2  SWS.

Participants

There are exactly 20 places.

Language

The course will be held in English.

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