3 # $Id: Base64.pm,v 3.9 2005/11/26 10:47:48 gisle Exp $
6 use vars qw(@ISA @EXPORT $VERSION);
10 @EXPORT = qw(encode_base64 decode_base64);
15 XSLoader::load('MIME::Base64', $VERSION);
17 *encode = \&encode_base64;
18 *decode = \&decode_base64;
26 MIME::Base64 - Encoding and decoding of base64 strings
32 $encoded = encode_base64('Aladdin:open sesame');
33 $decoded = decode_base64($encoded);
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.
44 The following functions are provided:
48 =item encode_base64($str)
50 =item encode_base64($str, $eol);
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 $eol unless it is empty. Pass an
57 empty string as second argument if you do not want the encoded string
58 to be broken into lines.
60 =item decode_base64($str)
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.
66 Any character not part of the 65-character base64 subset is
67 silently ignored. Characters occurring after a '=' padding character
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>.
76 If you prefer not to import these routines into your namespace, you can
80 $encoded = MIME::Base64::encode($decoded);
81 $decoded = MIME::Base64::decode($encoded);
85 The following warnings can be generated if perl is invoked with the
90 =item Premature end of base64 data
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 anyway be as if
95 the padding was there.
97 =item Premature padding of base64 data
99 The '=' padding character occurs as the first or second character
104 The following exception can be raised:
108 =item Wide character in subroutine entry
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
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):
124 use MIME::Base64 qw(encode_base64);
126 open(FILE, "/var/log/wtmp") or die "$!";
127 while (read(FILE, $buf, 60*57)) {
128 print encode_base64($buf);
131 or if you know you have enough memory
133 use MIME::Base64 qw(encode_base64);
134 local($/) = undef; # slurp
135 print encode_base64(<STDIN>);
137 The same approach as a command line:
139 perl -MMIME::Base64 -0777 -ne 'print encode_base64($_)' <file
141 Decoding does not need slurp mode if every line contains a multiple
142 of four base64 chars:
144 perl -MMIME::Base64 -ne 'print decode_base64($_)' <file
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
152 use MIME::Base64 qw(encode_base64);
153 use Encode qw(encode);
155 $encoded = encode_base64(encode("UTF-8", "\x{FFFF}\n"));
160 Copyright 1995-1999, 2001-2004 Gisle Aas.
162 This library is free software; you can redistribute it and/or
163 modify it under the same terms as Perl itself.
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>
170 The XS implementation uses code from metamail. Copyright 1991 Bell
171 Communications Research, Inc. (Bellcore)