ACHTERBAHN-128/80
is a synchronous stream cipher supporting the key lengths of 80 bits and 128 bits, respectively. ACHTERBAHN-128 is downward compatible and can produce the same keystream as ACHTERBAHN-80 if so desired.

The Achterbahn stream cipher is optimized for hardware applications with restricted resources, such as limited gate count and power consumption. An implementation of ACHTERBAHN-80 has a design size of only 2188 gate equivalents (Nand-GE) for throughputs upto 400Mbit/s and is suited for RFID tags. A high-speed implementation with a throughput of 8 Gbit/s has a design size of 8651 Nand-GE, see [Ref.].

Achterbahn is a joint work of Berndt Gammel, Rainer Göttfert and Oliver Kniffler.

Read  also the Wikipedia article.