Base64 is a group of similar binary-to-text encoding schemes that represent binary data in an ASCII string format by translating it into a radix-64 representation. It is specified in RFC 4648.
A 64-character string specifying the regular Base64 alphabet.
A 64-character string specifying the URI- and filename-safe Base64 alphabet.
decode s decodes the string s that is encoded in base64 format.
Will leave trailing NULLs on the string, padding it out to a multiple
of 3 characters.
encode s encodes the string s into base64. If pad is false,
no trailing padding is added.