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84 lines
3.2 KiB
PHTML
84 lines
3.2 KiB
PHTML
12 years ago
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<?php
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/**
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* Encode in Base32 based on RFC 4648.
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* Requires 20% more space than base64
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* Great for case-insensitive filesystems like Windows and URL's (except for = char which can be excluded using the pad option for urls)
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*
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* @package default
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* @author Bryan Ruiz
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**/
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class Base32 {
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private static $map = array(
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'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', // 7
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'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', // 15
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'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', // 23
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'Y', 'Z', '2', '3', '4', '5', '6', '7', // 31
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'=' // padding char
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);
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private static $flippedMap = array(
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'A'=>'0', 'B'=>'1', 'C'=>'2', 'D'=>'3', 'E'=>'4', 'F'=>'5', 'G'=>'6', 'H'=>'7',
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'I'=>'8', 'J'=>'9', 'K'=>'10', 'L'=>'11', 'M'=>'12', 'N'=>'13', 'O'=>'14', 'P'=>'15',
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'Q'=>'16', 'R'=>'17', 'S'=>'18', 'T'=>'19', 'U'=>'20', 'V'=>'21', 'W'=>'22', 'X'=>'23',
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'Y'=>'24', 'Z'=>'25', '2'=>'26', '3'=>'27', '4'=>'28', '5'=>'29', '6'=>'30', '7'=>'31'
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);
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/**
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* Use padding false when encoding for urls
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*
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* @return base32 encoded string
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* @author Bryan Ruiz
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**/
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public static function encode($input, $padding = true) {
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if(empty($input)) return "";
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$input = str_split($input);
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$binaryString = "";
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for($i = 0; $i < count($input); $i++) {
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$binaryString .= str_pad(base_convert(ord($input[$i]), 10, 2), 8, '0', STR_PAD_LEFT);
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}
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$fiveBitBinaryArray = str_split($binaryString, 5);
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$base32 = "";
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$i=0;
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while($i < count($fiveBitBinaryArray)) {
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$base32 .= self::$map[base_convert(str_pad($fiveBitBinaryArray[$i], 5,'0'), 2, 10)];
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$i++;
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}
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if($padding && ($x = strlen($binaryString) % 40) != 0) {
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if($x == 8) $base32 .= str_repeat(self::$map[32], 6);
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else if($x == 16) $base32 .= str_repeat(self::$map[32], 4);
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else if($x == 24) $base32 .= str_repeat(self::$map[32], 3);
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else if($x == 32) $base32 .= self::$map[32];
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}
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return $base32;
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}
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public static function decode($input) {
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if(empty($input)) return;
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$paddingCharCount = substr_count($input, self::$map[32]);
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$allowedValues = array(6,4,3,1,0);
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if(!in_array($paddingCharCount, $allowedValues)) return false;
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for($i=0; $i<4; $i++){
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if($paddingCharCount == $allowedValues[$i] &&
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substr($input, -($allowedValues[$i])) != str_repeat(self::$map[32], $allowedValues[$i])) return false;
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}
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$input = str_replace('=','', $input);
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$input = str_split($input);
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$binaryString = "";
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for($i=0; $i < count($input); $i = $i+8) {
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$x = "";
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if(!in_array($input[$i], self::$map)) return false;
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for($j=0; $j < 8; $j++) {
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$x .= str_pad(base_convert(@self::$flippedMap[@$input[$i + $j]], 10, 2), 5, '0', STR_PAD_LEFT);
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}
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$eightBits = str_split($x, 8);
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for($z = 0; $z < count($eightBits); $z++) {
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$binaryString .= ( ($y = chr(base_convert($eightBits[$z], 2, 10))) || ord($y) == 48 ) ? $y:"";
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}
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}
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return $binaryString;
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}
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}
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