content: package gov2.nist.javax2.sip.clientauthutils;
  
  import gov2.nist.core.StackLogger;
  
  import java.security.MessageDigest;
  import java.security.NoSuchAlgorithmException;
  
  /**
   * The class takes standard Http Authentication details and returns a response according to the
   * MD5 algorithm
   * 
   * @author Emil Ivov
   */
  
  public class MessageDigestAlgorithm {
      /**
       * Calculates an http authentication response in accordance with rfc2617.
       * <p>
       * 
       * @param algorithm a string indicating a pair of algorithms (MD5 (default), or MD5-sess) used
       *        to produce the digest and a checksum.
       * @param hashUserNameRealmPasswd MD5 hash of (username:realm:password)
       * @param nonce_value A server-specified data string provided in the challenge.
       * @param cnonce_value an optional client-chosen value whose purpose is to foil chosen
       *        plaintext attacks.
       * @param method the SIP method of the request being challenged.
       * @param digest_uri_value the value of the "uri" directive on the Authorization header in the
       *        request.
       * @param entity_body the entity-body
       * @param qop_value Indicates what "quality of protection" the client has applied to the
       *        message.
       * @param nc_value the hexadecimal count of the number of requests (including the current
       *        request) that the client has sent with the nonce value in this request.
       * @return a digest response as defined in rfc2617
       * @throws NullPointerException in case of incorrectly null parameters.
       */
      
      static String calculateResponse(String algorithm, String hashUserNameRealmPasswd,
              String nonce_value, String nc_value, String cnonce_value,
              String method, String digest_uri_value, String entity_body, String qop_value,
              StackLogger stackLogger)  {
      	// Changed by Deutsche Telekom
          if (stackLogger!=null && stackLogger.isLoggingEnabled()) {
              stackLogger.logDebug("trying to authenticate using : " + algorithm + ", "+
                      hashUserNameRealmPasswd + ", " + nonce_value + ", "
                      + nc_value + ", " + cnonce_value + ", " + method + ", " + digest_uri_value
                      + ", " + entity_body + ", " + qop_value);
          }
          
          if (hashUserNameRealmPasswd == null || method == null
                  || digest_uri_value == null || nonce_value == null)
              throw new NullPointerException(
                      "Null parameter to MessageDigestAlgorithm.calculateResponse()");
  
          // The following follows closely the algorithm for generating a response
          // digest as specified by rfc2617
          
          if (cnonce_value == null || cnonce_value.length() == 0)
                  throw new NullPointerException(
                          "cnonce_value may not be absent for MD5-Sess algorithm.");
  
       
          String A2 = null;
          if (qop_value == null || qop_value.trim().length() == 0
                  || qop_value.trim().equalsIgnoreCase("auth")) {
              A2 = method + ":" + digest_uri_value;
          } else {
              if (entity_body == null)
                  entity_body = "";
              A2 = method + ":" + digest_uri_value + ":" + H(entity_body);
          }
  
          String request_digest = null;
  
          if (cnonce_value != null && qop_value != null && nc_value != null
                  && (qop_value.equalsIgnoreCase("auth") || qop_value.equalsIgnoreCase("auth-int")))
  
          {
              request_digest = KD(hashUserNameRealmPasswd, nonce_value + ":" + nc_value + ":" + cnonce_value + ":"
                      + qop_value + ":" + H(A2));
  
          } else {
              request_digest = KD(hashUserNameRealmPasswd, nonce_value + ":" + H(A2));
          }
  
          return request_digest;
          
          
      }
  
      /**
       * Calculates an http authentication response in accordance with rfc2617.
       * <p>
       * 
       * @param algorithm a string indicating a pair of algorithms (MD5 (default), or MD5-sess) used
       *        to produce the digest and a checksum.
       * @param username_value username_value (see rfc2617)
       * @param realm_value A string that has been displayed to the user in order to determine the
       *        context of the username and password to use.
       * @param passwd the password to encode in the challenge response.
       * @param nonce_value A server-specified data string provided in the challenge.
       * @param cnonce_value an optional client-chosen value whose purpose is to foil chosen
       *        plaintext attacks.
       * @param method the SIP method of the request being challenged.
       * @param digest_uri_value the value of the "uri" directive on the Authorization header in the
       *        request.
       * @param entity_body the entity-body
       * @param qop_value Indicates what "quality of protection" the client has applied to the
       *        message.
       * @param nc_value the hexadecimal count of the number of requests (including the current
       *        request) that the client has sent with the nonce value in this request.
       * @return a digest response as defined in rfc2617
       * @throws NullPointerException in case of incorrectly null parameters.
       */
      static String calculateResponse(String algorithm, String username_value, String realm_value,
              String passwd, String nonce_value, String nc_value, String cnonce_value,
              String method, String digest_uri_value, String entity_body, String qop_value,
              StackLogger stackLogger) {
      	// Changed by Deutsche Telekom
          if (stackLogger!=null && stackLogger.isLoggingEnabled()) {
              stackLogger.logDebug("trying to authenticate using : " + algorithm + ", "
                      + username_value + ", " + realm_value + ", "
                      + (passwd != null && passwd.trim().length() > 0) + ", " + nonce_value + ", "
                      + nc_value + ", " + cnonce_value + ", " + method + ", " + digest_uri_value
                      + ", " + entity_body + ", " + qop_value);
          }
  
          if (username_value == null || realm_value == null || passwd == null || method == null
                  || digest_uri_value == null || nonce_value == null)
              throw new NullPointerException(
                      "Null parameter to MessageDigestAlgorithm.calculateResponse()");
  
          // The following follows closely the algorithm for generating a response
          // digest as specified by rfc2617
          String A1 = null;
  
          if (algorithm == null || algorithm.trim().length() == 0
                  || algorithm.trim().equalsIgnoreCase("MD5")) {
              A1 = username_value + ":" + realm_value + ":" + passwd;
          } else {
              if (cnonce_value == null || cnonce_value.length() == 0)
                  throw new NullPointerException(
                          "cnonce_value may not be absent for MD5-Sess algorithm.");
  
              A1 = H(username_value + ":" + realm_value + ":" + passwd) + ":" + nonce_value + ":"
                      + cnonce_value;
          }
  
          String A2 = null;
          if (qop_value == null || qop_value.trim().length() == 0
                  || qop_value.trim().equalsIgnoreCase("auth")) {
              A2 = method + ":" + digest_uri_value;
          } else {
              if (entity_body == null)
                  entity_body = "";
              A2 = method + ":" + digest_uri_value + ":" + H(entity_body);
          }
  
          String request_digest = null;
  
          if (cnonce_value != null && qop_value != null && nc_value != null
                  && (qop_value.equalsIgnoreCase("auth") || qop_value.equalsIgnoreCase("auth-int")))
  
          {
              request_digest = KD(H(A1), nonce_value + ":" + nc_value + ":" + cnonce_value + ":"
                      + qop_value + ":" + H(A2));
  
          } else {
              request_digest = KD(H(A1), nonce_value + ":" + H(A2));
          }
  
          return request_digest;
      }
  
      /**
       * Defined in rfc 2617 as H(data) = MD5(data);
       * 
       * @param data data
       * @return MD5(data)
       */
      private static String H(String data) {
          try {
              MessageDigest digest = MessageDigest.getInstance("MD5");
  
              return toHexString(digest.digest(data.getBytes()));
          } catch (NoSuchAlgorithmException ex) {
              // shouldn't happen
              throw new RuntimeException("Failed to instantiate an MD5 algorithm", ex);
          }
      }
  
      /**
       * Defined in rfc 2617 as KD(secret, data) = H(concat(secret, ":", data))
       * 
       * @param data data
       * @param secret secret
       * @return H(concat(secret, ":", data));
       */
      private static String KD(String secret, String data) {
          return H(secret + ":" + data);
      }
  
      // the following code was copied from the NIST-SIP instant
      // messenger (its author is Olivier Deruelle). Thanks for making it public!
      /**
       * to hex converter
       */
      private static final char[] toHex = {
          '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
      };
  
      /**
       * Converts b[] to hex string.
       * 
       * @param b the bte array to convert
       * @return a Hex representation of b.
       */
      private static String toHexString(byte b[]) {
          int pos = 0;
          char[] c = new char[b.length * 2];
          for (int i = 0; i < b.length; i++) {
              c[pos++] = toHex[(b[i] >> 4) & 0x0F];
              c[pos++] = toHex[b[i] & 0x0f];
          }
          return new String(c);
      }
  }
  