2 # $Id: Base64.pm,v 2.16 2001/02/24 06:28:10 gisle Exp $
8 MIME::Base64 - Encoding and decoding of base64 strings
14 $encoded = encode_base64('Aladdin:open sesame');
15 $decoded = decode_base64($encoded);
19 This module provides functions to encode and decode strings into the
20 Base64 encoding specified in RFC 2045 - I<MIME (Multipurpose Internet
21 Mail Extensions)>. The Base64 encoding is designed to represent
22 arbitrary sequences of octets in a form that need not be humanly
23 readable. A 65-character subset ([A-Za-z0-9+/=]) of US-ASCII is used,
24 enabling 6 bits to be represented per printable character.
26 The following functions are provided:
30 =item encode_base64($str, [$eol])
32 Encode data by calling the encode_base64() function. The first
33 argument is the string to encode. The second argument is the line
34 ending sequence to use (it is optional and defaults to C<"\n">). The
35 returned encoded string is broken into lines of no more than 76
36 characters each and it will end with $eol unless it is empty. Pass an
37 empty string as second argument if you do not want the encoded string
40 =item decode_base64($str)
42 Decode a base64 string by calling the decode_base64() function. This
43 function takes a single argument which is the string to decode and
44 returns the decoded data.
46 Any character not part of the 65-character base64 subset set is
47 silently ignored. Characters occuring after a '=' padding character
50 If the length of the string to decode (after ignoring
51 non-base64 chars) is not a multiple of 4 or padding occurs too early,
52 then a warning is generated if perl is running under C<-w>.
56 If you prefer not to import these routines into your namespace you can
60 $encoded = MIME::Base64::encode($decoded);
61 $decoded = MIME::Base64::decode($encoded);
65 The following warnings might be generated if perl is invoked with the
70 =item Premature end of base64 data
72 The number of characters to decode is not a multiple of 4. Legal
73 base64 data should be padded with one or two "=" characters to make
74 its length a multiple of 4. The decoded result will anyway be as if
75 the padding was there.
77 =item Premature padding of base64 data
79 The '=' padding character occurs as the first or second character
86 If you want to encode a large file, you should encode it in chunks
87 that are a multiple of 57 bytes. This ensures that the base64 lines
88 line up and that you do not end up with padding in the middle. 57
89 bytes of data fills one complete base64 line (76 == 57*4/3):
91 use MIME::Base64 qw(encode_base64);
93 open(FILE, "/var/log/wtmp") or die "$!";
94 while (read(FILE, $buf, 60*57)) {
95 print encode_base64($buf);
98 or if you know you have enough memory
100 use MIME::Base64 qw(encode_base64);
101 local($/) = undef; # slurp
102 print encode_base64(<STDIN>);
104 The same approach as a command line:
106 perl -MMIME::Base64 -0777 -ne 'print encode_base64($_)' <file
108 Decoding does not need slurp mode if all the lines contains a multiple
111 perl -MMIME::Base64 -ne 'print decode_base64($_)' <file
115 Copyright 1995-1999, 2001 Gisle Aas.
117 This library is free software; you can redistribute it and/or
118 modify it under the same terms as Perl itself.
120 Distantly based on LWP::Base64 written by Martijn Koster
121 <m.koster@nexor.co.uk> and Joerg Reichelt <j.reichelt@nexor.co.uk> and
122 code posted to comp.lang.perl <3pd2lp$6gf@wsinti07.win.tue.nl> by Hans
123 Mulder <hansm@wsinti07.win.tue.nl>
125 The XS implementation use code from metamail. Copyright 1991 Bell
126 Communications Research, Inc. (Bellcore)
131 use vars qw(@ISA @EXPORT $VERSION $OLD_CODE);
135 @ISA = qw(Exporter DynaLoader);
136 @EXPORT = qw(encode_base64 decode_base64);
140 eval { bootstrap MIME::Base64 $VERSION; };
142 # can't bootstrap XS implementation, use perl implementation
143 *encode_base64 = \&old_encode_base64;
144 *decode_base64 = \&old_decode_base64;
150 # Historically this module has been implemented as pure perl code.
151 # The XS implementation runs about 20 times faster, but the Perl
152 # code might be more portable, so it is still here.
156 sub old_encode_base64 ($;$)
160 $eol = "\n" unless defined $eol;
161 pos($_[0]) = 0; # ensure start at the beginning
163 $res = join '', map( pack('u',$_)=~ /^.(\S*)/, ($_[0]=~/(.{1,45})/gs));
165 $res =~ tr|` -_|AA-Za-z0-9+/|; # `# help emacs
166 # fix padding at the end
167 my $padding = (3 - length($_[0]) % 3) % 3;
168 $res =~ s/.{$padding}$/'=' x $padding/e if $padding;
169 # break encoded string into lines of no more than 76 characters each
171 $res =~ s/(.{1,76})/$1$eol/g;
177 sub old_decode_base64 ($)
179 local($^W) = 0; # unpack("u",...) gives bogus warning in 5.00[123]
182 $str =~ tr|A-Za-z0-9+=/||cd; # remove non-base64 chars
183 if (length($str) % 4) {
185 Carp::carp("Length of base64 data not a multiple of 4")
187 $str =~ s/=+$//; # remove padding
188 $str =~ tr|A-Za-z0-9+/| -_|; # convert to uuencoded format
190 return join'', map( unpack("u", chr(32 + length($_)*3/4) . $_),
191 $str =~ /(.{1,60})/gs);
194 # Set up aliases so that these functions also can be called as
196 # MIME::Base64::encode();
197 # MIME::Base64::decode();
199 *encode = \&encode_base64;
200 *decode = \&decode_base64;