Trivium
A minimalist hardware-oriented stream cipher from eSTREAM, with an 80-bit key and an internal state of 288 bits.
Trivium was designed by Christophe De Cannière and Bart Preneel and submitted to the eSTREAM hardware profile. It takes an 80-bit key and an 80-bit IV, and its 288-bit state is spread across three shift registers of different lengths. Initialisation runs 1152 state updates before the keystream starts.
Its simplicity and small area made it popular in research. Its security margin has been questioned, though: Maximov and Biryukov published an attack in 2007 that was considerably faster than earlier attacks on similar designs. The construction is built from shift registers, like LFSRs, as is A5/1.