Converting a byte array to string and then back again produced different results

A binary data may not be converted to string and then back to byte array using Encoding.[AnyEncoding].GetBytes and Encoding.[AnyEncoding].GetString

Instead use Convert.ToBase64String and Convert.FromBase64String

You can easily test...

var bytes = new byte[] { 255, 255, 255 }; 
var buf = Encoding.UTF8.GetString(bytes);
var newbytes = Encoding.UTF8.GetBytes(buf);

newbytes's length will be 9.....

Edit: This is the test case for @Theo

var bytes = new byte[] { 0, 216 }; //any new byte[] { X, 216 };
var buf = Encoding.Unicode.GetString(bytes);
var newbytes = Encoding.Unicode.GetBytes(buf); //253,255