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

       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	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 primary functions are provided:

       encode_base64( $bytes )
       encode_base64( $bytes, $eol );
	   Encode data by calling the encode_base64() function.	 The first
	   argument is the byte	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 to be	broken into lines.

	   The function	will croak with	"Wide character	in subroutine entry"
	   if $bytes 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.

       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 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);

       Additional functions not	exported by default:

       encode_base64url( $bytes	)
       decode_base64url( $str )
	   Encode and decode according to the base64 scheme for	"URL
	   applications" [1].  This is a variant of the	base64 encoding	which
	   does	not use	padding, does not break	the string into	multiple lines
	   and use the characters "-" and "_" instead of "+" and "/" to	avoid
	   using reserved URL characters.

       encoded_base64_length( $bytes )
       encoded_base64_length( $bytes, $eol )
	   Returns the length that the encoded string would have without
	   actually encoding it.  This will return the same value as
	   "length(encode_base64($bytes))", but	should be more efficient.

       decoded_base64_length( $str )
	   Returns the length that the decoded string would have without
	   actually decoding it.  This will return the same value as
	   "length(decode_base64($str))", but should be	more efficient.

       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 every line contains	a multiple of
       four base64 chars:

	  perl -MMIME::Base64 -ne 'print decode_base64($_)' <file

       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::Base64 qw(encode_base64);
	   use Encode qw(encode);

	   $encoded = encode_base64(encode("UTF-8", "\x{FFFF}\n"));
	   print $encoded;

       Copyright 1995-1999, 2001-2004, 2010 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
       <> and Joerg	Reichelt <> and
       code posted to comp.lang.perl <3pd2lp$> by Hans
       Mulder <>

       The XS implementation uses code from metamail.  Copyright 1991 Bell
       Communications Research,	Inc. (Bellcore)


       [1] <>

perl v5.32.1			  2020-09-27		       MIME::Base64(3)


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