Heres an SHA1 function that will work on it's own completely. This is for users who are using below PHP 4.3.0. it works same as PHP5 ( being able to return raw output ).

<?php

/*
** Date modified: 1st October 2004 20:09 GMT
*
** PHP implementation of the Secure Hash Algorithm ( SHA-1 )
*
** This code is available under the GNU Lesser General Public License:
** http://www.gnu.org/licenses/lgpl.txt
*
** Based on the PHP implementation by Marcus Campbell
** http://www.tecknik.net/sha-1/
*
** This is a slightly modified version by me Jerome Clarke ( sinatosk@gmail.com )
** because I feel more comfortable with this
*/

function sha1_str2blks_SHA1($str)
{
    $strlen_str = strlen($str);
    
    $nblk = (($strlen_str + 8) >> 6) + 1;
    
    for ($i=0; $i < $nblk * 16; $i++) $blks[$i] = 0;
    
    for ($i=0; $i < $strlen_str; $i++)
    {
        $blks[$i >> 2] |= ord(substr($str, $i, 1)) << (24 - ($i % 4) * 8);
    }
    
    $blks[$i >> 2] |= 0x80 << (24 - ($i % 4) * 8);
    $blks[$nblk * 16 - 1] = $strlen_str * 8;
    
    return $blks;
}

function sha1_safe_add($x, $y)
{
    $lsw = ($x & 0xFFFF) + ($y & 0xFFFF);
    $msw = ($x >> 16) + ($y >> 16) + ($lsw >> 16);
    
    return ($msw << 16) | ($lsw & 0xFFFF);
}

function sha1_rol($num, $cnt)
{
    return ($num << $cnt) | sha1_zeroFill($num, 32 - $cnt);    
}

function sha1_zeroFill($a, $b)
{
    $bin = decbin($a);
    
    $strlen_bin = strlen($bin);
    
    $bin = $strlen_bin < $b ? 0 : substr($bin, 0, $strlen_bin - $b);
    
    for ($i=0; $i < $b; $i++) $bin = '0'.$bin;
    
    return bindec($bin);
}

function sha1_ft($t, $b, $c, $d)
{
    if ($t < 20) return ($b & $c) | ((~$b) & $d);
    if ($t < 40) return $b ^ $c ^ $d;
    if ($t < 60) return ($b & $c) | ($b & $d) | ($c & $d);
    
    return $b ^ $c ^ $d;
}

function sha1_kt($t)
{
    if ($t < 20) return 1518500249;
    if ($t < 40) return 1859775393;
    if ($t < 60) return -1894007588;
    
    return -899497514;
}

function sha1($str, $raw_output=FALSE)
{
    if ( $raw_output === TRUE ) return pack('H*', sha1($str, FALSE));
    
    $x = sha1_str2blks_SHA1($str);
    $a =  1732584193;
    $b = -271733879;
    $c = -1732584194;
    $d =  271733878;
    $e = -1009589776;
    
    $x_count = count($x);
    
    for ($i = 0; $i < $x_count; $i += 16)
    {
        $olda = $a;
        $oldb = $b;
        $oldc = $c;
        $oldd = $d;
        $olde = $e;
        
        for ($j = 0; $j < 80; $j++)
        {
            $w[$j] = ($j < 16) ? $x[$i + $j] : sha1_rol($w[$j - 3] ^ $w[$j - 8] ^ $w[$j - 14] ^ $w[$j - 16], 1);
            
            $t = sha1_safe_add(sha1_safe_add(sha1_rol($a, 5), sha1_ft($j, $b, $c, $d)), sha1_safe_add(sha1_safe_add($e, $w[$j]), sha1_kt($j)));
            $e = $d;
            $d = $c;
            $c = sha1_rol($b, 30);
            $b = $a;
            $a = $t;
        }
        
        $a = sha1_safe_add($a, $olda);
        $b = sha1_safe_add($b, $oldb);
        $c = sha1_safe_add($c, $oldc);
        $d = sha1_safe_add($d, $oldd);
        $e = sha1_safe_add($e, $olde);
    }
    
    return sprintf('%08x%08x%08x%08x%08x', $a, $b, $c, $d, $e);
}

?>