1 | #
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2 | # $Id: Base64.pm 718 1999-10-19 02:36:47Z davidb $
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3 |
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4 | package MIME::Base64;
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5 |
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6 | =head1 NAME
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7 |
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8 | MIME::Base64 - Encoding and decoding of base64 strings
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9 |
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10 | =head1 SYNOPSIS
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11 |
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12 | use MIME::Base64;
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13 |
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14 | $encoded = encode_base64('Aladdin:open sesame');
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15 | $decoded = decode_base64($encoded);
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16 |
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17 | =head1 DESCRIPTION
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18 |
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19 | This module provides functions to encode and decode strings into the
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20 | Base64 encoding specified in RFC 2045 - I<MIME (Multipurpose Internet
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21 | Mail Extensions)>. The Base64 encoding is designed to represent
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22 | arbitrary sequences of octets in a form that need not be humanly
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23 | readable. A 65-character subset ([A-Za-z0-9+/=]) of US-ASCII is used,
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24 | enabling 6 bits to be represented per printable character.
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25 |
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26 | The following functions are provided:
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27 |
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28 | =over 4
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29 |
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30 | =item encode_base64($str, [$eol])
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31 |
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32 | Encode data by calling the encode_base64() function. The first
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33 | argument is the string to encode. The second argument is the line
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34 | ending sequence to use (it is optional and defaults to C<"\n">). The
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35 | returned encoded string is broken into lines of no more than 76
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36 | characters each and it will end with $eol unless it is empty. Pass an
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37 | empty string as second argument if you do not want the encoded string
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38 | broken into lines.
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39 |
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40 | =item decode_base64($str)
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41 |
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42 | Decode a base64 string by calling the decode_base64() function. This
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43 | function takes a single argument which is the string to decode and
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44 | returns the decoded data.
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45 |
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46 | Any character not part of the 65-character base64 subset set is
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47 | silently ignored. Characters occuring after a '=' padding character
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48 | are never decoded.
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49 |
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50 | If the length of the string to decode (after ignoring
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51 | non-base64 chars) is not a multiple of 4 or padding occurs too ealy,
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52 | then a warning is generated if perl is running under C<-w>.
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53 |
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54 | =back
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55 |
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56 | If you prefer not to import these routines into your namespace you can
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57 | call them as:
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58 |
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59 | use MIME::Base64 ();
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60 | $encoded = MIME::Base64::encode($decoded);
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61 | $decoded = MIME::Base64::decode($encoded);
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62 |
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63 | =head1 DIAGNOSTICS
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64 |
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65 | The following warnings might be generated if perl is invoked with the
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66 | C<-w> switch:
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67 |
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68 | =over 4
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69 |
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70 | =item Premature end of base64 data
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71 |
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72 | The number of characters to decode is not a multiple of 4. Legal
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73 | base64 data should be padded with one or two "=" characters to make
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74 | its length a multiple of 4. The decoded result will anyway be as if
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75 | the padding was there.
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76 |
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77 | =item Premature padding of base64 data
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78 |
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79 | The '=' padding character occurs as the first or second character
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80 | in a base64 quartet.
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81 |
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82 | =back
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83 |
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84 | =head1 EXAMPLES
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85 |
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86 | If you want to encode a large file, you should encode it in chunks
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87 | that are a multiple of 57 bytes. This ensures that the base64 lines
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88 | line up and that you do not end up with padding in the middle. 57
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89 | bytes of data fills one complete base64 line (76 == 57*4/3):
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90 |
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91 | use MIME::Base64 qw(encode_base64);
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92 |
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93 | open(FILE, "/var/log/wtmp") or die "$!";
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94 | while (read(FILE, $buf, 60*57)) {
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95 | print encode_base64($buf);
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96 | }
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97 |
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98 | or if you know you have enough memory
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99 |
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100 | use MIME::Base64 qw(encode_base64);
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101 | local($/) = undef; # slurp
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102 | print encode_base64(<STDIN>);
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103 |
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104 | =head1 COPYRIGHT
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105 |
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106 | Copyright 1995-1999 Gisle Aas.
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107 |
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108 | This library is free software; you can redistribute it and/or
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109 | modify it under the same terms as Perl itself.
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110 |
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111 | Distantly based on LWP::Base64 written by Martijn Koster
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112 | <[email protected]> and Joerg Reichelt <[email protected]> and
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113 | code posted to comp.lang.perl <[email protected]> by Hans
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114 | Mulder <[email protected]>
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115 |
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116 | The XS implementation use code from metamail. Copyright 1991 Bell
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117 | Communications Research, Inc. (Bellcore)
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118 |
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119 | =cut
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120 |
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121 | use strict;
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122 | use vars qw(@ISA @EXPORT $VERSION $OLD_CODE);
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123 |
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124 | require Exporter;
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125 | require DynaLoader;
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126 | @ISA = qw(Exporter DynaLoader);
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127 | @EXPORT = qw(encode_base64 decode_base64);
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128 |
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129 | $VERSION = '2.11';
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130 |
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131 | eval { bootstrap MIME::Base64 $VERSION; };
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132 | if ($@) {
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133 | # can't bootstrap XS implementation, use perl implementation
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134 | *encode_base64 = \&old_encode_base64;
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135 | *decode_base64 = \&old_decode_base64;
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136 |
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137 | $OLD_CODE = $@;
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138 | #warn $@ if $^W;
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139 | }
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140 |
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141 | # Historically this module has been implemented as pure perl code.
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142 | # The XS implementation runs about 20 times faster, but the Perl
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143 | # code might be more portable, so it is still here.
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144 |
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145 | use integer;
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146 |
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147 | sub old_encode_base64 ($;$)
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148 | {
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149 | my $res = "";
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150 | my $eol = $_[1];
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151 | $eol = "\n" unless defined $eol;
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152 | pos($_[0]) = 0; # ensure start at the beginning
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153 | while ($_[0] =~ /(.{1,45})/gs) {
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154 | $res .= substr(pack('u', $1), 1);
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155 | chop($res);
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156 | }
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157 | $res =~ tr|` -_|AA-Za-z0-9+/|; # `# help emacs
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158 | # fix padding at the end
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159 | my $padding = (3 - length($_[0]) % 3) % 3;
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160 | $res =~ s/.{$padding}$/'=' x $padding/e if $padding;
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161 | # break encoded string into lines of no more than 76 characters each
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162 | if (length $eol) {
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163 | $res =~ s/(.{1,76})/$1$eol/g;
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164 | }
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165 | $res;
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166 | }
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167 |
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168 |
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169 | sub old_decode_base64 ($)
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170 | {
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171 | local($^W) = 0; # unpack("u",...) gives bogus warning in 5.00[123]
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172 |
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173 | my $str = shift;
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174 | my $res = "";
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175 |
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176 | $str =~ tr|A-Za-z0-9+=/||cd; # remove non-base64 chars
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177 | if (length($str) % 4) {
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178 | require Carp;
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179 | Carp::carp("Length of base64 data not a multiple of 4")
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180 | }
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181 | $str =~ s/=+$//; # remove padding
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182 | $str =~ tr|A-Za-z0-9+/| -_|; # convert to uuencoded format
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183 | while ($str =~ /(.{1,60})/gs) {
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184 | my $len = chr(32 + length($1)*3/4); # compute length byte
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185 | $res .= unpack("u", $len . $1 ); # uudecode
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186 | }
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187 | $res;
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188 | }
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189 |
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190 | # Set up aliases so that these functions also can be called as
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191 | #
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192 | # MIME::Base64::encode();
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193 | # MIME::Base64::decode();
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194 |
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195 | *encode = \&encode_base64;
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196 | *decode = \&decode_base64;
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197 |
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198 | 1;
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