1package MIME::Base64; 2 3# $Id: Base64.pm,v 3.1 2004/03/29 11:55:49 gisle Exp $ 4 5use strict; 6use vars qw(@ISA @EXPORT $VERSION); 7 8require Exporter; 9require DynaLoader; 10@ISA = qw(Exporter DynaLoader); 11@EXPORT = qw(encode_base64 decode_base64); 12 13$VERSION = '3.01'; 14 15MIME::Base64->bootstrap($VERSION); 16 17*encode = \&encode_base64; 18*decode = \&decode_base64; 19 201; 21 22__END__ 23 24=head1 NAME 25 26MIME::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 37This module provides functions to encode and decode strings into and from the 38base64 encoding specified in RFC 2045 - I<MIME (Multipurpose Internet 39Mail Extensions)>. The base64 encoding is designed to represent 40arbitrary sequences of octets in a form that need not be humanly 41readable. A 65-character subset ([A-Za-z0-9+/=]) of US-ASCII is used, 42enabling 6 bits to be represented per printable character. 43 44The following functions are provided: 45 46=over 4 47 48=item encode_base64($str) 49 50=item encode_base64($str, $eol); 51 52Encode data by calling the encode_base64() function. The first 53argument is the string to encode. The second argument is the 54line-ending sequence to use. It is optional and defaults to "\n". The 55returned encoded string is broken into lines of no more than 76 56characters each and it will end with $eol unless it is empty. Pass an 57empty string as second argument if you do not want the encoded string 58to be broken into lines. 59 60=item decode_base64($str) 61 62Decode a base64 string by calling the decode_base64() function. This 63function takes a single argument which is the string to decode and 64returns the decoded data. 65 66Any character not part of the 65-character base64 subset is 67silently ignored. Characters occurring after a '=' padding character 68are never decoded. 69 70If the length of the string to decode, after ignoring 71non-base64 chars, is not a multiple of 4 or if padding occurs too early, 72then a warning is generated if perl is running under C<-w>. 73 74=back 75 76If you prefer not to import these routines into your namespace, you can 77call them as: 78 79 use MIME::Base64 (); 80 $encoded = MIME::Base64::encode($decoded); 81 $decoded = MIME::Base64::decode($encoded); 82 83=head1 DIAGNOSTICS 84 85The following warnings can be generated if perl is invoked with the 86C<-w> switch: 87 88=over 4 89 90=item Premature end of base64 data 91 92The number of characters to decode is not a multiple of 4. Legal 93base64 data should be padded with one or two "=" characters to make 94its length a multiple of 4. The decoded result will anyway be as if 95the padding was there. 96 97=item Premature padding of base64 data 98 99The '=' padding character occurs as the first or second character 100in a base64 quartet. 101 102=back 103 104=head1 EXAMPLES 105 106If you want to encode a large file, you should encode it in chunks 107that are a multiple of 57 bytes. This ensures that the base64 lines 108line up and that you do not end up with padding in the middle. 57 109bytes of data fills one complete base64 line (76 == 57*4/3): 110 111 use MIME::Base64 qw(encode_base64); 112 113 open(FILE, "/var/log/wtmp") or die "$!"; 114 while (read(FILE, $buf, 60*57)) { 115 print encode_base64($buf); 116 } 117 118or if you know you have enough memory 119 120 use MIME::Base64 qw(encode_base64); 121 local($/) = undef; # slurp 122 print encode_base64(<STDIN>); 123 124The same approach as a command line: 125 126 perl -MMIME::Base64 -0777 -ne 'print encode_base64($_)' <file 127 128Decoding does not need slurp mode if every line contains a multiple 129of four base64 chars: 130 131 perl -MMIME::Base64 -ne 'print decode_base64($_)' <file 132 133=head1 COPYRIGHT 134 135Copyright 1995-1999, 2001-2004 Gisle Aas. 136 137This library is free software; you can redistribute it and/or 138modify it under the same terms as Perl itself. 139 140Distantly based on LWP::Base64 written by Martijn Koster 141<m.koster@nexor.co.uk> and Joerg Reichelt <j.reichelt@nexor.co.uk> and 142code posted to comp.lang.perl <3pd2lp$6gf@wsinti07.win.tue.nl> by Hans 143Mulder <hansm@wsinti07.win.tue.nl> 144 145The XS implementation uses code from metamail. Copyright 1991 Bell 146Communications Research, Inc. (Bellcore) 147 148=head1 SEE ALSO 149 150L<MIME::QuotedPrint> 151 152=cut 153