Doc/lib/libbase64.tex

   1 \section{\module{base64} ---
   2          Encode and decode MIME base64 data}
   3
   4 \declaremodule{standard}{base64}
   5 \modulesynopsis{Encode and decode files using the MIME base64 data.}
   6
   7
   8 \indexii{base64}{encoding}
   9 \index{MIME!base64 encoding}
  10
  11 This module performs base64 encoding and decoding of arbitrary binary
  12 strings into text strings that can be safely emailed or posted.  The
  13 encoding scheme is defined in \rfc{1521} (\emph{MIME
  14 (Multipurpose Internet Mail Extensions) Part One: Mechanisms for
  15 Specifying and Describing the Format of Internet Message Bodies},
  16 section 5.2, ``Base64 Content-Transfer-Encoding'') and is used for
  17 MIME email and various other Internet-related applications; it is not
  18 the same as the output produced by the \program{uuencode} program.
  19 For example, the string \code{'www.python.org'} is encoded as the
  20 string \code{'d3d3LnB5dGhvbi5vcmc=\e n'}.
  21
  22
  23 \begin{funcdesc}{decode}{input, output}
  24 Decode the contents of the \var{input} file and write the resulting
  25 binary data to the \var{output} file.
  26 \var{input} and \var{output} must either be file objects or objects that
  27 mimic the file object interface. \var{input} will be read until
  28 \code{\var{input}.read()} returns an empty string.
  29 \end{funcdesc}
  30
  31 \begin{funcdesc}{decodestring}{s}
  32 Decode the string \var{s}, which must contain one or more lines of
  33 base64 encoded data, and return a string containing the resulting
  34 binary data.
  35 \end{funcdesc}
  36
  37 \begin{funcdesc}{encode}{input, output}
  38 Encode the contents of the \var{input} file and write the resulting
  39 base64 encoded data to the \var{output} file.
  40 \var{input} and \var{output} must either be file objects or objects that
  41 mimic the file object interface. \var{input} will be read until
  42 \code{\var{input}.read()} returns an empty string.
  43 \end{funcdesc}
  44
  45 \begin{funcdesc}{encodestring}{s}
  46 Encode the string \var{s}, which can contain arbitrary binary data,
  47 and return a string containing one or more lines of
  48 base64 encoded data.
  49 \end{funcdesc}
  50
  51
  52 \begin{seealso}
  53   \seemodule{binascii}{support module containing \ASCII{}-to-binary
  54                        and binary-to-\ASCII{} conversions}
  55   \seetext{Internet \rfc{1521}, \emph{MIME (Multipurpose Internet
  56            Mail Extensions) Part One: Mechanisms for Specifying and
  57            Describing the Format of Internet Message Bodies}, section
  58            5.2, ``Base64 Content-Transfer-Encoding,'' provides the
  59            definition of the base64 encoding.}
  60 \end{seealso}