Provides <a href="http://en.wikipedia.org/wiki/Base64">Base 64</a> encoding and decoding as defined by <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>. <p/> This class implements section <cite>6.8. Base64 Content-Transfer-Encoding</cite> from RFC 2045 <cite>Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies</cite> by Freed and Borenstein. <p/> This class was borrowed from Apache Commons Codec SVN repository (rev. 618419) with modifications to enable Base64 conversion without a full dependency on Commons Codec. We didn't want to reinvent the wheel of great work they've done, but also didn't want to force every Shiro user to depend on the commons-codec.jar <p/> As per the Apache 2.0 license, the original copyright notice and all author and copyright information have remained in tact.