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package utils.security;import javax.crypto.Mac;import javax.crypto.spec.SecretKeySpec;import java.io.UnsupportedEncodingException;import java.net.URL;import java.net.URLEncoder;import java.net.URLDecoder;import java.util.TreeMap;import java.util.Map;import java.util.Iterator;import org.apache.commons.codec.binary.Base64;public class SigHelper{	private static final String HMAC_SHA1_ALGORITHM = "HmacSHA1";		public static String getSignedUrl(String url, String key) throws Exception	{		return url + "&Signature=" + URLEncoder.encode(getSignature(url, key), "UTF-8");	}	public static String getSignature(String url, String key) throws Exception	{		URL u = new URL(url);		return computeSignature(key, makeParamMap(u.getQuery()));	}	private static String computeSignature(String callerSecretKey, TreeMap<String, String> sortedMap) throws Exception	{		StringBuffer strToSign = new StringBuffer("");		// Raise exception if caller key unknown		if (callerSecretKey == null || callerSecretKey.equals(""))			throw new RuntimeException("Invalid callid for computeSignature");		for (Iterator i = sortedMap.entrySet().iterator(); i.hasNext();)		{			Map.Entry e = (Map.Entry) i.next();			String key = (String) e.getKey();			String[] value = (String[]) e.getValue();			for (int j = 0; j < value.length; j++)			{				System.out.println("SigHelper.java: From parameter '" + key	+ "' adding " + " value '" + value[j] + "'");				strToSign.append(key);				strToSign.append(value[j]);			}		}		System.out.println("SigHelper.java: Attempting to sign string '" + strToSign.toString());		return calculateSig(callerSecretKey, strToSign.toString());	}	private static String calculateSig(String secretKey, String parametersToHash)	{		String result;		try		{			SecretKeySpec signingKey = new SecretKeySpec(secretKey.getBytes(), HMAC_SHA1_ALGORITHM);			Mac mac = Mac.getInstance(HMAC_SHA1_ALGORITHM);			mac.init(signingKey);			byte[] rawHmac = mac.doFinal(parametersToHash.getBytes());			String encodedHMac = new String (Base64.encodeBase64Chunked (rawHmac));				// The following API behaves differently on windows and Linux			if (System.getProperty("os.name").startsWith("Windows"))				result = encodedHMac.substring(0, encodedHMac.length() - 2);			else 				result = encodedHMac.substring(0, encodedHMac.length() - 2);		} catch (Exception e)		{			throw new RuntimeException("Error Calculating Hmac", e);		}		return result;	}	private static TreeMap<String, String> makeParamMap(String queryString) throws UnsupportedEncodingException	{		TreeMap hmp = new TreeMap(String.CASE_INSENSITIVE_ORDER);		String[] param = queryString.split("&");		for (int i = 0; i < param.length; i++)		{			int index = param[i].indexOf("=");			String key = param[i].substring(0, index);			String value = param[i].substring(index + 1);			System.out.println("SigHelper.java: Adding " + key + " = " + value);			if (hmp.get(key) == null)				hmp.put(key, new String[] { URLDecoder.decode(value, "UTF-8") });			else			{				// Very Rare Case				String[] arr = (String[]) hmp.get(key);				String[] arrNew = new String[arr.length + 1];				arrNew[arr.length] = URLDecoder.decode(value, "UTF-8");				for (int j = 0; j < arr.length; j++)					arrNew[j] = arr[j];			}		}		return hmp;	}}