Java in dual 4.5 and hash

	//Get SHA1 Hash.
	
	//Java version does not support hash uploading. That is why you should make sure that this value 
	//is actually uploaded.
	if (array_key_exists("HashCodeSHA_1", $_POST))
	{
		$postedSHA1Hash = $_POST ["HashCodeSHA_1"];

		//Compute SHA1 hash. Since Image Uploader sends the hash value encoded with Base 64 algorithm
		//the result should be also encoded with Base 64.
		$actualSHA1Hash = base64_encode(pack("H*",sha1_file($_FILES["SourceFile_1"]['tmp_name'])));
		
		//If the result differs from the uploaded one, the upload should be interpreted as corrupted.
		if ($postedSHA1Hash != $actualSHA1Hash)
		{
			header("HTTP/1.0 400 Bad Request");
			return;
		}
	}