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elisp: Base 64

 
 31.24 Base 64 Encoding
 ======================
 
 Base 64 code is used in email to encode a sequence of 8-bit bytes as a
 longer sequence of ASCII graphic characters.  It is defined in Internet
 RFC(1)2045.  This section describes the functions for converting to and
 from this code.
 
  -- Command: base64-encode-region beg end &optional no-line-break
      This function converts the region from BEG to END into base 64
      code.  It returns the length of the encoded text.  An error is
      signaled if a character in the region is multibyte, i.e., in a
      multibyte buffer the region must contain only characters from the
      charsets ‘ascii’, ‘eight-bit-control’ and ‘eight-bit-graphic’.
 
      Normally, this function inserts newline characters into the encoded
      text, to avoid overlong lines.  However, if the optional argument
      NO-LINE-BREAK is non-‘nil’, these newlines are not added, so the
      output is just one long line.
 
  -- Function: base64-encode-string string &optional no-line-break
      This function converts the string STRING into base 64 code.  It
      returns a string containing the encoded text.  As for
      ‘base64-encode-region’, an error is signaled if a character in the
      string is multibyte.
 
      Normally, this function inserts newline characters into the encoded
      text, to avoid overlong lines.  However, if the optional argument
      NO-LINE-BREAK is non-‘nil’, these newlines are not added, so the
      result string is just one long line.
 
  -- Command: base64-decode-region beg end
      This function converts the region from BEG to END from base 64 code
      into the corresponding decoded text.  It returns the length of the
      decoded text.
 
      The decoding functions ignore newline characters in the encoded
      text.
 
  -- Function: base64-decode-string string
      This function converts the string STRING from base 64 code into the
      corresponding decoded text.  It returns a unibyte string containing
      the decoded text.
 
      The decoding functions ignore newline characters in the encoded
      text.
 
    ---------- Footnotes ----------
 
    (1) An RFC, an acronym for “Request for Comments”, is a numbered
 Internet informational document describing a standard.  RFCs are usually
 written by technical experts acting on their own initiative, and are
 traditionally written in a pragmatic, experience-driven manner.
 

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