Service.java

package com.vuzit;

import java.util.Date;
import java.security.SignatureException;
import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;

public class Service
{
   // Public static variables
   private static String publicKey = null;
   private static String privateKey = null;
   private static String serviceUrl = "http://vuzit.com";
   private static final String productName = "VuzitJava Library 2.1.0";
   private static String userAgent = productName;
   private static final String HMAC_SHA1_ALGORITHM = "HmacSHA1";

   // Public getter and setter variables

   /**
    * Returns the public key.  
    */
   public static String getPublicKey()
   {
     return publicKey;
   }

   /**
    * Sets the public key.
    */
   public static void setPublicKey(String key)
   {
     publicKey = key;
   }

   /**
    * Returns the private key.  
    */
   public static String getPrivateKey()
   {
     return privateKey;
   }

   /**
    * Sets the private key.
    */
   public static void setPrivateKey(String key)
   {
     privateKey = key;
   }

   /**
    * Returns the service URL.  
    */
   public static String getServiceUrl()
   {
     return serviceUrl;
   }

   /**
    * Sets the service URL.  
    */
   public static void setServiceUrl(String url)
   {
     url = url.trim();
     if(url.endsWith("/")) {
       throw new RuntimeException("Trailing slashes (/) in service URLs are invalid");
     }
     serviceUrl = url;
   }

   /**
    * Returns the user agent. 
    */
   public static String getUserAgent()
   {
     return userAgent;
   }

   /**
    * Sets the user agent.  
    */
   public static void setUserAgent(String agent)
   {
     userAgent = (agent + " (" + productName + ")");
   }

   // Public static methods

   /**
    * Converts a date to the date at epoch time.  
    */
   public static long epochTime(Date date)
   {
     return (date.getTime() / 1000);
   }

   /**
    * Returns a valid Vuzit request signature.  
    */
   public static String signature(String service, String id, Date date)
   {
     return signature(service, id, date, new OptionList());
   }

   /**
    * Returns a valid Vuzit request signature.  
    */
   public static String signature(String service, String id, 
                                  Date date, OptionList options)
   {
     String result;

     if(id == null) {
       id = "";
     }

     if(date == null) {
       date = new Date();
     }

     String msg = service + id + publicKey + epochTime(date);

     String[] optionsList = new String[] { "included_pages", 
                                           "watermark", 
                                           "query" };

     for(int i = 0; i < optionsList.length; i++) {
       String item = optionsList[i];
       if (options.contains(item)) {
         msg += options.get(item);
       }
     }


     try {
       result = calculateRFC2104HMAC(msg, privateKey);
     } catch (Exception e) {
       result = null;
     }

     return result;
   }

   // Private static methods

   /**
    * Computes RFC 2104-compliant HMAC signature.
    */
   private static String calculateRFC2104HMAC(String data, String key)
     throws java.security.SignatureException
   {
     String result;

     try {
       // get an hmac_sha1 key from the raw key bytes
       SecretKeySpec signingKey = new SecretKeySpec(key.getBytes(), HMAC_SHA1_ALGORITHM);

       // get an hmac_sha1 Mac instance and initialize with the signing key
       Mac mac = Mac.getInstance(HMAC_SHA1_ALGORITHM);
       mac.init(signingKey);

       // compute the hmac on input data bytes
       byte[] rawHmac = mac.doFinal(data.getBytes());

       // base64-encode the hmac
       result = Base64.encodeBytes(rawHmac);

     } catch (Exception e) {
       throw new SignatureException("Failed to generate HMAC : " + e.getMessage());
     }

     return result;
   }

}