Collision analysis of the GMR-2 cipher used in the satellite phone

A collision property analysis of the GMR-2 cipher used in the satellite phone was presented.By using the F-component as a bridge,the link between the difference of the key byte and the collision of the output ofFas well as the link between the collision of the output of F and the collision of keystream byte were analyzed,which finally revealed the relationship between the difference of the original key byte and the keystream collision.The theoretical analysis showed that for a random frame number,a special chosen key pair could lead to a keystream collision with a high probability,when the key pair has only one byte difference in which the most significant 4 bit of the difference was equal to the last significant 4 bit.The experimental result shows that the keystream collision probability is 2^?8.248,which is far higher than the ideal collision probability 2^?120.This proves once again,that there exists serious potential security hazards in the GMR-2 cipher.