NewDecoder constructs a new base64 stream decoder.

NewEncoder returns a new base64 stream encoder.

NewEncoding returns a new Encoding defined by the given alphabet, which must be a 64-byte string.

StdEncoding is the standard base64 encoding, as defined in RFC 4648.

URLEncoding is the alternate base64 encoding defined in RFC 4648.

An Encoding is a radix 64 encoding/decoding scheme, defined by a 64-character alphabet.