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Thread: Google Cart and the HMAC_SHA1 function

  1. #1
    Join Date
    Jul 2006
    Posts
    146

    Google Cart and the HMAC_SHA1 function

    Googles instructions state that i have to use this HMAC_SHA1 function for some kind of encryption alogorithm.

    Is anyone familiar with this?

    (my obeisance absolute)

  2. #2
    Join Date
    Dec 2002
    Location
    Seattle, WA
    Posts
    1,676
    SHA-1 is built into php >= 4.0, this is what i made to force raw_output in older version of php:
    Code:
    <?php
    function shr($x, $n)
    {
    	return (0x80000000 & $x) ? (($x >> 1) & ~0x80000000 | 0x40000000) >> ($n - 1) : ($x >> $n);
    }
    function rotl($x, $n)
    {
    	return ($x << $n) | shr($x, (32 - $n));
    }
    if(phpversion() >= '5.0')
    {
    	function sha160($str, $raw_output = false)
    	{
    		return sha1($str, $raw_output);
    	}
    }
    else if(phpversion() >= '4.3')
    {
    	function sha160($str, $raw_output = false)
    	{
    		$hash = sha1($str);
    		return ($raw_output) ? bin2hex($hash) : $hash;
    	}
    }
    else
    {
    	function sha160($str, $raw_output = false)
    	{
    		$h0 = 0x67452301;
    		$h1 = 0xefcdaB89;
    		$h2 = 0x98badcfe;
    		$h3 = 0x10325476;
    		$h4 = 0xc3d2e1f0;
    		$l = strlen($str);
    		$str .= "\x80" . str_repeat("\x0", ($l & ~63) + (($l & 63 < 56) ? 60 : 124)) . pack('N', $l << 3);
    
    		for($i = 0; $i < strlen($str); $i += 64)
    		{
    			$w = array_values(unpack('N16', substr($str, $i, 64)));
    			$a = $h0;
    			$b = $h1;
    			$c = $h2;
    			$d = $h3;
    			$e = $h4;
    
    			for($t = 0; $t <= 79; $t++)
    			{
    				if(16 <= $t)
    				{
    					$w[] = rotl($w[$t - 3] ^ $w[$t - 8] ^ $w[$t - 14] ^ $w[$t - 16], 1);
    				}
    				if(0 <= $t && $t <= 19)
    				{
    					$f = ($b & $c) ^ (~$b & $d);
    					$k = 0x5a827999;
    				}
    				else if(20 <= $t && $t <= 39)
    				{
    					$f = $b ^ $c ^ $d;
    					$k = 0x6ed9eba1;
    				}
    				else if(40 <= $t && $t <= 59)
    				{
    					$f = ($b & $c) ^ ($b & $d) ^ ($c & $d);
    					$k = 0x8f1bbcdc;
    				}
    				else if(60 <= $t && $t <= 79)
    				{
    					$f = $b ^ $c ^ $d;
    					$k = 0xca62c1d6;
    				}
    				$tmp = intval(rotl($a, 5) + $f + $e + $k + $w[$t]);
    				$e = $d;
    				$d = $c;
    				$c = rotl($b, 30);
    				$b = $a;
    				$a = $tmp;
    			}
    			$h0 = $a + $h0;
    			$h1 = $b + $h1;
    			$h2 = $c + $h2;
    			$h3 = $d + $h3;
    			$h4 = $e + $h4;
    		}
    		$hash = pack('N*', $h0, $h1, $h2, $h3, $h4);
    		return ($raw_output) ? bin2hex($hash) : $hash;
    	}
    }
    ?>

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