The Security Analysis Of The Dedicated Hash Functions

Hash functions can be used for checking the integrality of dates , and ensure the safety of cryptogrammic system, such as digital signature,group signature,MAC codes,electronic cash,electronic election and bit promise , and so on.We discuss the basic design principles and cryptanalysis methods on the MD families and SHA family , and describe some of their other weakness .What's more , we analyze the message expansion of SHA-1 and put forward a new kind of message expansion of SHA-1 . At the same time , we analyze the safety of the property of the compress functions of SHA-0 . We use tunnels to find the collisions of SHA-0 , basing on the difference attack . By the attack texts , we find that the attack result is quite effective in collision attack.