Trivium (cipher)

Trivium is a synchronous stream cipher designed to provide a flexible trade-off between speed and gate count in hardware, and reasonably efficient software implementation.

It is the simplest eSTREAM entrant; while it shows remarkable resistance to cryptanalysis for its simplicity and performance, recent attacks leave the security margin looking rather slim.

A straightforward hardware implementation of Trivium would use 3488 logic gates and produce one bit per clock cycle.

[Trivium] was designed as an exercise in exploring how far a stream cipher can be simplified without sacrificing its security, speed or flexibility.

The cube attack requires 268 steps to break a variant of Trivium where the number of initialization rounds is reduced to 799.

[8] These attacks improve on the well-known time-space tradeoff attack on stream ciphers, which with Trivium's 288-bit internal state would take 2144 steps, and show that a variant on Trivium which made no change except to increase the key length beyond the 80 bits mandated by eSTREAM Profile 2 would not be secure.