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   1  package MIME::Base64;
   2  
   3  # $Id: Base64.pm,v 3.11 2005/11/29 20:59:55 gisle Exp $
   4  
   5  use strict;
   6  use vars qw(@ISA @EXPORT $VERSION);
   7  
   8  require Exporter;
   9  @ISA = qw(Exporter);
  10  @EXPORT = qw(encode_base64 decode_base64);
  11  
  12  $VERSION = '3.07_01';
  13  
  14  require XSLoader;
  15  XSLoader::load('MIME::Base64', $VERSION);
  16  
  17  *encode = \&encode_base64;
  18  *decode = \&decode_base64;
  19  
  20  1;
  21  
  22  __END__
  23  
  24  =head1 NAME
  25  
  26  MIME::Base64 - Encoding and decoding of base64 strings
  27  
  28  =head1 SYNOPSIS
  29  
  30   use MIME::Base64;
  31  
  32   $encoded = encode_base64('Aladdin:open sesame');
  33   $decoded = decode_base64($encoded);
  34  
  35  =head1 DESCRIPTION
  36  
  37  This module provides functions to encode and decode strings into and from the
  38  base64 encoding specified in RFC 2045 - I<MIME (Multipurpose Internet
  39  Mail Extensions)>. The base64 encoding is designed to represent
  40  arbitrary sequences of octets in a form that need not be humanly
  41  readable. A 65-character subset ([A-Za-z0-9+/=]) of US-ASCII is used,
  42  enabling 6 bits to be represented per printable character.
  43  
  44  The following functions are provided:
  45  
  46  =over 4
  47  
  48  =item encode_base64($str)
  49  
  50  =item encode_base64($str, $eol);
  51  
  52  Encode data by calling the encode_base64() function.  The first
  53  argument is the string to encode.  The second argument is the
  54  line-ending sequence to use.  It is optional and defaults to "\n".  The
  55  returned encoded string is broken into lines of no more than 76
  56  characters each and it will end with $eol unless it is empty.  Pass an
  57  empty string as second argument if you do not want the encoded string
  58  to be broken into lines.
  59  
  60  =item decode_base64($str)
  61  
  62  Decode a base64 string by calling the decode_base64() function.  This
  63  function takes a single argument which is the string to decode and
  64  returns the decoded data.
  65  
  66  Any character not part of the 65-character base64 subset is
  67  silently ignored.  Characters occurring after a '=' padding character
  68  are never decoded.
  69  
  70  If the length of the string to decode, after ignoring
  71  non-base64 chars, is not a multiple of 4 or if padding occurs too early,
  72  then a warning is generated if perl is running under C<-w>.
  73  
  74  =back
  75  
  76  If you prefer not to import these routines into your namespace, you can
  77  call them as:
  78  
  79      use MIME::Base64 ();
  80      $encoded = MIME::Base64::encode($decoded);
  81      $decoded = MIME::Base64::decode($encoded);
  82  
  83  =head1 DIAGNOSTICS
  84  
  85  The following warnings can be generated if perl is invoked with the
  86  C<-w> switch:
  87  
  88  =over 4
  89  
  90  =item Premature end of base64 data
  91  
  92  The number of characters to decode is not a multiple of 4.  Legal
  93  base64 data should be padded with one or two "=" characters to make
  94  its length a multiple of 4.  The decoded result will be the same
  95  whether the padding is present or not.
  96  
  97  =item Premature padding of base64 data
  98  
  99  The '=' padding character occurs as the first or second character
 100  in a base64 quartet.
 101  
 102  =back
 103  
 104  The following exception can be raised:
 105  
 106  =over 4
 107  
 108  =item Wide character in subroutine entry
 109  
 110  The string passed to encode_base64() contains characters with code
 111  above 255.  The base64 encoding is only defined for single-byte
 112  characters.  Use the Encode module to select the byte encoding you
 113  want.
 114  
 115  =back
 116  
 117  =head1 EXAMPLES
 118  
 119  If you want to encode a large file, you should encode it in chunks
 120  that are a multiple of 57 bytes.  This ensures that the base64 lines
 121  line up and that you do not end up with padding in the middle. 57
 122  bytes of data fills one complete base64 line (76 == 57*4/3):
 123  
 124     use MIME::Base64 qw(encode_base64);
 125  
 126     open(FILE, "/var/log/wtmp") or die "$!";
 127     while (read(FILE, $buf, 60*57)) {
 128         print encode_base64($buf);
 129     }
 130  
 131  or if you know you have enough memory
 132  
 133     use MIME::Base64 qw(encode_base64);
 134     local($/) = undef;  # slurp
 135     print encode_base64(<STDIN>);
 136  
 137  The same approach as a command line:
 138  
 139     perl -MMIME::Base64 -0777 -ne 'print encode_base64($_)' <file
 140  
 141  Decoding does not need slurp mode if every line contains a multiple
 142  of four base64 chars:
 143  
 144     perl -MMIME::Base64 -ne 'print decode_base64($_)' <file
 145  
 146  Perl v5.8 and better allow extended Unicode characters in strings.
 147  Such strings cannot be encoded directly, as the base64
 148  encoding is only defined for single-byte characters.  The solution is
 149  to use the Encode module to select the byte encoding you want.  For
 150  example:
 151  
 152      use MIME::Base64 qw(encode_base64);
 153      use Encode qw(encode);
 154  
 155      $encoded = encode_base64(encode("UTF-8", "\x{FFFF}\n"));
 156      print $encoded;
 157  
 158  =head1 COPYRIGHT
 159  
 160  Copyright 1995-1999, 2001-2004 Gisle Aas.
 161  
 162  This library is free software; you can redistribute it and/or
 163  modify it under the same terms as Perl itself.
 164  
 165  Distantly based on LWP::Base64 written by Martijn Koster
 166  <m.koster@nexor.co.uk> and Joerg Reichelt <j.reichelt@nexor.co.uk> and
 167  code posted to comp.lang.perl <3pd2lp$6gf@wsinti07.win.tue.nl> by Hans
 168  Mulder <hansm@wsinti07.win.tue.nl>
 169  
 170  The XS implementation uses code from metamail.  Copyright 1991 Bell
 171  Communications Research, Inc. (Bellcore)
 172  
 173  =head1 SEE ALSO
 174  
 175  L<MIME::QuotedPrint>
 176  
 177  =cut