The COFB Mode of Operation and Its Security Analysis

In this paper, on the basis of counter mode and output feedback mode, a novel block cipher mode of operation - COFB was proposed. In the new scheme, a nonce N was used. The novel mode solves the synchronization question of CTR mode by the nonce and the circular question of OFB mode by xoring a random value. The new scheme is provable secure if the underlying block cipher is a pseudorandom permutation