\section{\module{base64} ---
         Encode and decode MIME base64 data}

\declaremodule{standard}{base64}
\modulesynopsis{Encode and decode files using the MIME base64 data.}


\indexii{base64}{encoding}
\index{MIME!base64 encoding}

This module performs base64 encoding and decoding of arbitrary binary
strings into text strings that can be safely emailed or posted.  The
encoding scheme is defined in \rfc{1521} (\emph{MIME
(Multipurpose Internet Mail Extensions) Part One: Mechanisms for
Specifying and Describing the Format of Internet Message Bodies},
section 5.2, ``Base64 Content-Transfer-Encoding'') and is used for
MIME email and various other Internet-related applications; it is not
the same as the output produced by the \program{uuencode} program.
For example, the string \code{'www.python.org'} is encoded as the
string \code{'d3d3LnB5dGhvbi5vcmc=\e n'}.  


\begin{funcdesc}{decode}{input, output}
Decode the contents of the \var{input} file and write the resulting
binary data to the \var{output} file.
\var{input} and \var{output} must either be file objects or objects that
mimic the file object interface. \var{input} will be read until
\code{\var{input}.read()} returns an empty string.
\end{funcdesc}

\begin{funcdesc}{decodestring}{s}
Decode the string \var{s}, which must contain one or more lines of
base64 encoded data, and return a string containing the resulting
binary data.
\end{funcdesc}

\begin{funcdesc}{encode}{input, output}
Encode the contents of the \var{input} file and write the resulting
base64 encoded data to the \var{output} file.
\var{input} and \var{output} must either be file objects or objects that
mimic the file object interface. \var{input} will be read until
\code{\var{input}.read()} returns an empty string.
\end{funcdesc}

\begin{funcdesc}{encodestring}{s}
Encode the string \var{s}, which can contain arbitrary binary data,
and return a string containing one or more lines of
base64 encoded data.
\end{funcdesc}


\begin{seealso}
  \seemodule{binascii}{support module containing \ASCII{}-to-binary
                       and binary-to-\ASCII{} conversions}
  \seetext{Internet \rfc{1521}, \emph{MIME (Multipurpose Internet
           Mail Extensions) Part One: Mechanisms for Specifying and
           Describing the Format of Internet Message Bodies}, section
           5.2, ``Base64 Content-Transfer-Encoding,'' provides the
           definition of the base64 encoding.}
\end{seealso}