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MIME::Base64(3)
NAME
  MIME::Base64 - Encoding and decoding of base64 strings

SYNOPSIS
   use MIME::Base64;

   $encoded = encode_base64('Aladdin:open sesame');
   $decoded = decode_base64($encoded);

DESCRIPTION
  This module provides functions to encode and decode strings into the Base64
  encoding specified in RFC 2045 - MIME (Multipurpose Internet Mail
  Extensions). The Base64 encoding is designed to represent arbitrary
  sequences of octets in a form that need not be humanly readable. A
  65-character subset ([A-Za-z0-9+/=]) of US-ASCII is used, enabling 6 bits
  to be represented per printable character.

  The following functions are provided:

  encode_base64($str)
  encode_base64($str, $eol);
      Encode data by calling the encode_base64() function.  The first
      argument is the string to encode.	 The second argument is the line
      ending sequence to use.  It is optional and defaults to "\n".  The
      returned encoded string is broken into lines of no more than 76
      characters each and it will end with $eol unless it is empty.  Pass an
      empty string as second argument if you do not want the encoded string
      broken into lines.

  decode_base64($str)
      Decode a base64 string by calling the decode_base64() function.  This
      function takes a single argument which is the string to decode and
      returns the decoded data.

      Any character not part of the 65-character base64 subset set is
      silently ignored.	 Characters occuring after a '=' padding character
      are never decoded.

      If the length of the string to decode, after ignoring non-base64 chars,
      is not a multiple of 4 or padding occurs too early, then a warning is
      generated if perl is running under "-w".

  If you prefer not to import these routines into your namespace you can call
  them as:

      use MIME::Base64 ();
      $encoded = MIME::Base64::encode($decoded);
      $decoded = MIME::Base64::decode($encoded);

DIAGNOSTICS
  The following warnings might be generated if perl is invoked with the "-w"
  switch:

  Premature end of base64 data
      The number of characters to decode is not a multiple of 4.  Legal
      base64 data should be padded with one or two "=" characters to make its
      length a multiple of 4.  The decoded result will anyway be as if the
      padding was there.

  Premature padding of base64 data
      The '=' padding character occurs as the first or second character in a
      base64 quartet.

EXAMPLES
  If you want to encode a large file, you should encode it in chunks that are
  a multiple of 57 bytes.  This ensures that the base64 lines line up and
  that you do not end up with padding in the middle. 57 bytes of data fills
  one complete base64 line (76 == 57*4/3):

     use MIME::Base64 qw(encode_base64);

     open(FILE, "/var/log/wtmp") or die "$!";
     while (read(FILE, $buf, 60*57)) {
	 print encode_base64($buf);
     }

  or if you know you have enough memory

     use MIME::Base64 qw(encode_base64);
     local($/) = undef;	 # slurp
     print encode_base64(<STDIN>);

  The same approach as a command line:

     perl -MMIME::Base64 -0777 -ne 'print encode_base64($_)' <file

  Decoding does not need slurp mode if all the lines contains a multiple of 4
  base64 chars:

     perl -MMIME::Base64 -ne 'print decode_base64($_)' <file

COPYRIGHT
  Copyright 1995-1999, 2001-2003 Gisle Aas.

  This library is free software; you can redistribute it and/or modify it
  under the same terms as Perl itself.

  Distantly based on LWP::Base64 written by Martijn Koster
  <m.koster@nexor.co.uk> and Joerg Reichelt <j.reichelt@nexor.co.uk> and code
  posted to comp.lang.perl <3pd2lp$6gf@wsinti07.win.tue.nl> by Hans Mulder
  <hansm@wsinti07.win.tue.nl>

  The XS implementation use code from metamail.	 Copyright 1991 Bell
  Communications Research, Inc. (Bellcore)

SEE ALSO
  MIME::QuotedPrint

Index for Section 3

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