Dragon is a stream cipher

Stream cipher

In cryptography, a stream cipher is a symmetric key cipher where plaintext digits are combined with a pseudorandom cipher digit stream . In a stream cipher the plaintext digits are encrypted one at a time, and the transformation of successive digits varies during the encryption...

 developed at the Information Security Institute by Ed Dawson, Kevin Chen, Matt Henricksen, William Millan, Leonie Simpson, HoonJae Lee, and SangJae Moon.

The cipher is a Phase 3 Focus candidate for the eSTREAM

ESTREAM

eSTREAM is a project to "identify new stream ciphers suitable for widespread adoption", organised by the EU ECRYPT network. It was set up as a result of the failure of all six stream ciphers submitted to the NESSIE project. The call for primitives was first issued in November 2004. The project was...

project. The cipher is targeted for fast software implementations and versions with different key lengths exists. The version selected for Phase 3 is Dragon-128. It is not patented.

Dragon has not been successfully attacked to date, but Cho and Pieprzyk found biases within the primary non-linear component of the cipher. This suggests that the security of the cipher is weaker than intended by its designers.