ext::MIME::Base64PerlsProgrammers Reext::MIME::Base64::Base64(3p)NAMEMIME::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 and from 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 charac-
ters each and it will end with $eol unless it is empty.
Pass an empty string as second argument if you do not
want the encoded string to be broken into lines.
decode_base64($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
is silently ignored. Characters occurring 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 if 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);
perl v5.8.8 2005-02-05 1
ext::MIME::Base64PerlsProgrammers Reext::MIME::Base64::Base64(3p)DIAGNOSTICS
The following warnings can 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 be the same whether the padding is
present or not.
Premature padding of base64 data
The '=' padding character occurs as the first or second
character in a base64 quartet.
The following exception can be raised:
Wide character in subroutine entry
The string passed to encode_base64() contains characters
with code above 255. The base64 encoding is only
defined for single-byte characters. Use the Encode
module to select the byte encoding you want.
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::Base64qw(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::Base64qw(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 every line contains a
multiple of four base64 chars:
perl -MMIME::Base64 -ne 'print decode_base64($_)' <file
perl v5.8.8 2005-02-05 2
ext::MIME::Base64PerlsProgrammers Reext::MIME::Base64::Base64(3p)
Perl v5.8 and better allow extended Unicode characters in
strings. Such strings cannot be encoded directly, as the
base64 encoding is only defined for single-byte characters.
The solution is to use the Encode module to select the byte
encoding you want. For example:
use MIME::Base64qw(encode_base64);
use Encode qw(encode);
$encoded = encode_base64(encode("UTF-8", "\x{FFFF}\n"));
print $encoded;
COPYRIGHT
Copyright 1995-1999, 2001-2004 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 uses code from metamail. Copyright
1991 Bell Communications Research, Inc. (Bellcore)
SEE ALSO
MIME::QuotedPrint
perl v5.8.8 2005-02-05 3
