Base64(3)      User Contributed Perl Documentation      Base64(3)


NAME
       MIME::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 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($str, [$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
           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 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 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 ealy, 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);






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Base64(3)      User Contributed Perl Documentation      Base64(3)


DIAGNOSTICS
       The following warnings might 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 anyway be as if the padding
           was there.

       Premature padding of base64 data
           The '=' padding character occurs as the first or
           second character in a base64 quartet.

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::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
       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



24/Feb/2001            perl 5.005, patch 03                     2





Base64(3)      User Contributed Perl Documentation      Base64(3)


       <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)




















































24/Feb/2001            perl 5.005, patch 03                     3