You should NEVER keep the user password in any format, encrypted or not. Instead, you should only keep a hash value of the password through a one-way hashing algorithm (MD5, SHA-1, etc). To gain even higher security level, you may also consider adding some "salt" into the hashing process, meaning that append a random string/timestamp after the password before it goes into the hashing algorithm. For more detail, read: http://msdn.microsoft.com/msdnmag/issues/03/08/SecurityBriefs/default.aspx
要是想简单点，就自己取反，移位什么的搞搞
To gain even higher security level, you may also consider adding some "salt" into the hashing process, meaning that append a random string/timestamp after the password before it goes into the hashing algorithm. For more detail, read:
http://msdn.microsoft.com/msdnmag/issues/03/08/SecurityBriefs/default.aspx
或者你可以使用IE自带的加密算法crypt 你可以在MSDN中查找crypt 有例子