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103 lines
2.2 KiB
103 lines
2.2 KiB
<?PHP
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#error_reporting(E_ALL);
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// Examples:
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// $str = base85::encode("Hello world!");
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// $str = base85::decode(":e4D*;K$&\Er");
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class base85
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{
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public static function decode($str) {
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$str = preg_replace("/ \t\r\n\f/","",$str);
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$str = preg_replace("/z/","!!!!!",$str);
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$str = preg_replace("/y/","+<VdL/",$str);
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// Pad the end of the string so it's a multiple of 5
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$padding = 5 - (strlen($str) % 5);
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if (strlen($str) % 5 === 0) {
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$padding = 0;
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}
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$str .= str_repeat('u',$padding);
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$num = 0;
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$ret = '';
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// Foreach 5 chars, convert it to an integer
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while ($chunk = substr($str, $num * 5, 5)) {
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$tmp = 0;
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foreach (unpack('C*',$chunk) as $item) {
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$tmp *= 85;
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$tmp += $item - 33;
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}
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// Convert the integer in to a string
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$ret .= pack('N', $tmp);
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$num++;
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}
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// Remove any padding we had to add
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$ret = substr($ret,0,strlen($ret) - $padding);
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return $ret;
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}
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public static function encode($str) {
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$ret = '';
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$debug = 0;
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$padding = 4 - (strlen($str) % 4);
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if (strlen($str) % 4 === 0) {
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$padding = 0;
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}
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if ($debug) {
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printf("Length: %d = Padding: %s<br /><br />\n",strlen($str),$padding);
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}
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// If we don't have a four byte chunk, append \0s
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$str .= str_repeat("\0", $padding);
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foreach (unpack('N*',$str) as $chunk) {
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// If there is an all zero chunk, it has a shortcut of 'z'
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if ($chunk == "\0") {
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$ret .= "z";
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continue;
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}
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// Four spaces has a shortcut of 'y'
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if ($chunk == 538976288) {
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$ret .= "y";
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continue;
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}
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if ($debug) {
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var_dump($chunk); print "<br />\n";
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}
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// Convert the integer into 5 "quintet" chunks
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for ($a = 0; $a < 5; $a++) {
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$b = intval($chunk / (pow(85,4 - $a)));
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$ret .= chr($b + 33);
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if ($debug) {
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printf("%03d = %s <br />\n",$b,chr($b+33));
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}
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$chunk -= $b * pow(85,4 - $a);
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}
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}
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// If we added some null bytes, we remove them from the final string
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if ($padding) {
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$ret = preg_replace("/z$/",'!!!!!',$ret);
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$ret = substr($ret,0,strlen($ret) - $padding);
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}
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return $ret;
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}
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} // End of base85 class
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