I'm implementing serial key functionality in my application. User needs to enter at least 64bit number in order to register the application. Because typing number like 9,223,372,036,854,775,807 will take a while I want to compress it a bit. The first guess was to code this number hexadecimally but it still is quite long (0x7FFF FFFF FFFF FFFF).
Is there any standard method in .NET to code this number alphanumerically using for example: digits, upper-case and lower-case characters?