Password recovery attack on authentication protocol MD4(Password||Challenge)
Lei Wang, Kazuo Ohta, Noboru Kunihiro · 2008
Several widely used hash functions such as MD4 and MD5 have been proven to be insecure. As a result, it was announced that the security of APOP, which is a hash based challenge and response authentication protocol, is totally broken. Several candidates of strengthened APOP are considered. This paper deals with one of these candidates, which is described as Hash(Password||Challenge) whereas previous APOP is done as Hash(Challenge||Password). Actually, Hash(P||C) is already used in other protocols such as CHAP.