What is a base64 string?
Base64 is an encoding procedure to encode 8 bit binary data (i.e. executable programs, zip files or images) into a character sequence which does only consist of readable, code independent ASCII characters. In combination with for example OpenPGP an additional checksum is appedend. This slightly different approach is called Radix-64. Base 64 is additionally used as well for encoding the username and password in the HTTP Basic authentication.