MICKEY 2.0 is a hardware-efficient (profile 2), synchronous stream cipher designed by Steve Babbage and Matthew Dodd. The cipher makes use of a 80-bit key and an initialisation vector with up to 80 bits in length. The name MICKEY is short for "Mutual Irregular Clocking KEYstream generator". The cipher secret state consists of two 100-bit shift registers, one linear and one nonlinear, each of which is irregularly clocked under control of the other. The specific clocking mechanisms contribute cryptographic strength while still providing guarantees on period and pseudorandomness. The cipher specification states that each key can be used with up to 240 different IVs of the same length, and that 240 keystream bits can be generated from each key/IV pair. The designers have also specified a scaled-up version of the cipher called MICKEY-128 2.0, which takes a 128-bit key and an IV up to 128 bits.
MICKEY 2.0 can be implemented with a particularly small hardware footprint, making it a good candidate where low gate count or low power are the primary requirements. The irregular clocking means that it cannot readily be parallelised so as to run at high speed in software. Hardware performance of all profile-2 eSTREAM candidates (phase 3) was described in Good and Benaissa's paper at SASC 2008 (article). Prototype quantities of an ASIC containing all phase-3 hardware candidates was designed and fabricated on 0.18 μm CMOS, as part of the eSCARGOT project.
It has been noted, e.g. by Gierlichs et al. at SASC 2008 (article), that straightforward implementations of the MICKEY ciphers are likely to be susceptible to timing or power analysis attacks, where these are relevant. Otherwise there have been no known cryptanalytic advances against MICKEY 2.0 or MICKEY-128 2.0 since the publication of the eSTREAM portfolio.
The designers state that MICKEY 2.0 and MICKEY-128 2.0 are freely available for any use (see statement). We are not aware of the MICKEY ciphers yet being used in any products or standards.