On vulnerabilities and improvements of fast encryption algorithm for multimedia FEA-M

FEA-M is evaluated from cryptographic security of view and the weaknesses of its algebraic structure are pointed out which imply that the effective secret key size, under realistic known and chose plaintext attacks, is much smaller than its nominal one. Particularly, existence of a large class of the weak keys is shown. It appears that FEA-M is an insecure algorithm even if secret keys of 4096 bits are employed. On the other hand, it is shown that FEA-M is very sensitive on the packet loss errors. Finally, am improved variant of FEA-M is proposed which is resistant against the developed attacks, as well as to the packet loss errors.