MIME::Base64 - Encoding and decoding of base64 strings |
MIME::Base64 - Encoding and decoding of base64 strings
use MIME::Base64;
$encoded = encode_base64('Aladdin:open sesame'); $decoded = decode_base64($encoded);
This module provides functions to encode and decode strings into 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()
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
characters each and it will end with $eol unless it is empty. Pass an
empty string as second argument if you do not want the encoded string
broken into lines.
decode_base64($str)
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 set is silently ignored. Characters occuring 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 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);
The following warnings might be generated if perl is invoked with the
-w
switch:
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::Base64 qw(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::Base64 qw(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 all the lines contains a multiple of 4 base64 chars:
perl -MMIME::Base64 -ne 'print decode_base64($_)' <file
Copyright 1995-1999, 2001 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 use code from metamail. Copyright 1991 Bell Communications Research, Inc. (Bellcore)
MIME::Base64 - Encoding and decoding of base64 strings |