这是 64 位编码的吗？

Question

All of the passwords in our User DB look like this where we have == at the end:

91F2FSEYrFOcabeHK/UfNw==

So how can I tell if this is 64-bit encoded? It has to be because I can decode using a decode 64-bit routine I have.

I am trying now to figure out how to decode a literal string to 64-bit..back to the xxxxxxxx== and here is my code:

string passwordToEncrypt = "test";
byte[] passwordToBytes = System.Text.ASCIIEncoding.ASCII.GetBytes(passwordToEncrypt);
result = Convert.ToBase64String(passwordToBytes);

Updated:

I need the text test to come out in Base64 with the == at the end.

Answer 1

you have a typo in there - so the above code does not compile, try

        string passwordToEncrypte = "test";
        byte[] passwordToBytes = System.Text.ASCIIEncoding.ASCII.GetBytes(passwordToEncrypte);
        string result = Convert.ToBase64String(passwordToBytes);

result contains now a "Base64"-encoded password and end with "=="...

BUT the above code works only for passwords containing ASCII ... if you want it to work with UTF8 passwords then change it to:

        string passwordToEncrypte = "test";
        byte[] passwordToBytes = Encoding.UTF8.GetBytes(passwordToEncrypte);
        string result = Convert.ToBase64String(passwordToBytes);

to go back from Base64 to the original you need to do:

        string Original = Encoding.UTF8.GetString (Convert.FromBase64String(result));

see http://msdn.microsoft.com/en-us/library/86hf4sb8.aspx
andhttp://msdn.microsoft.com/en-us/library/system.convert.tobase64string.aspx
and http://msdn.microsoft.com/en-us/library/system.convert.frombase64string.aspx

Answer 2

Base64 encoded string doesn't always end with a =, it will only end with one or two = if they are required to pad the string out to the proper length.For more details checkout following link

Padding