FROG is an algorithm of Chiffrement of block proposed in 1998 within the framework of the Concours AES and designed by Dianelos Georgoudis, Damian Leroux and Billy Simón Chaves. It can work on blocks of variable size. The key length of coding can also be variable. The algorithm has 8 turns with a complex internal structure.

In 1999, David Wagner and Al published an analysis of the weak key of FROG. The algorithm also suffered from its slowness with operations of coding definitely less powerful than its competitors. The team of Wagner moreover found one fault related to a difference in quality in the diffusion of the bits between coding and the deciphering.

For these reasons, it was isolated final.