MD5 is not secure any more.

根據這邊的消息指出(大陸人真強.....):

A Collision in the full MD5 hash function was found by researchers in China.
Wang, Feng, Lai, and Yu published full collisions for:

MD4, MD5, HAVAL-128, and RIPEMD-128 This represents on the the most substantial developments in cryptography in recent years.

Using their technique, an MD5 collision can be found in a matter or hours!!!

也就是說你拿到MD5的Hash code之後，可以很快的找到一組經過MD5 Hash過後會產生相同Hash code的資料。因為如此，許多根據MD5而衍生出來的一些安全演算法，如數位簽章，也會變得不安全。

感謝丁大告訴我這個新知。