Difference in SHA1 in .NET and MySQL

The SHA1 hashes should be equal, but the representation is not. MySql outputs a hex-string, so you will need to do the same in .NET:

return String.Join(String.Empty, hashedPasswordBytes.Select(b => b.ToString("x2")))

The following will give you an exact match to what MySQL produces:

 BitConverter.ToString(SHA1CryptoServiceProvider.Create().ComputeHash(System.Text.ASCIIEncoding.ASCII.GetBytes(Password))).Replace("-", "").ToLower();

You need to put [?a??????%l?3~??? in HEX representation. What you are printing is probably in binary form (hence the multiple ? chars).

Try doing this:

string hexstring = BitConverter.ToString(hashedPasswordBytes);

And see if hexstring and MySQL hash match.

In the MySQL example you are encoding to a hexadecimal string, in the .NET example you are encoding in ASCII. The two encodings are not the same.

If you convert to hexadecimal in the .NET version you get the correct result:

string hex = BitConverter.ToString(hashedPasswordBytes);

Result:

5B-AA-61-E4-C9-B9-3F-3F-06-82-25-0B-6C-F8-33-1B-7E-E6-8F-D8