Base64 Encoding

The Base64 encoding scheme is described in RFC 2045. Base64 encoding converts binary data so that it can be transmitted over Internet mail. It's also used in HTTP basic authentication (although it provides no acutal security). Historically, Base64 is a successor to the uuencode/uudecode schemes of early Unix systems.

In Base64, each sequence of three bytes (3*8 bits) is converted to a sequence of four bytes (4*6 bits). Each Base 64 encoded byte has a value in the following 64 character set: {A-Z, a-z, 0-9, +, /}. The equal ('=') character can be used to pad the stream to a four byte boundary.

Base64 encoded data is obviously 33% larger since 4 bytes encode 3.