libb64 is a library of ANSI C routines for fast encoding/decoding of data
into and from a Base64-encoded format.  C++ wrappers are included, as well
as the source code for standalone encoding and decoding executables.

Base64 uses a subset of displayable ASCII characters, and is therefore a
useful encoding for storing binary data in a text file, such as XML, or
sending binary data over text-only communication channels.

WWW: http://libb64.sourceforge.net/