/*
 * Copyright 1999-2009 The Apache Software Foundation.
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 */
package org.apache.xml.security.algorithms.implementations;

import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.SecureRandom;
import java.security.spec.AlgorithmParameterSpec;

import javax.crypto.Mac;
import javax.crypto.SecretKey;

import org.apache.xml.security.algorithms.JCEMapper;
import org.apache.xml.security.algorithms.MessageDigestAlgorithm;
import org.apache.xml.security.algorithms.SignatureAlgorithmSpi;
import org.apache.xml.security.signature.XMLSignature;
import org.apache.xml.security.signature.XMLSignatureException;
import org.apache.xml.security.utils.Constants;
import org.apache.xml.security.utils.XMLUtils;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Text;

/**
 *
 * @author $Author: mullan $
 */
public abstract class IntegrityHmac extends SignatureAlgorithmSpi {
    
   /** {@link org.apache.commons.logging} logging facility */
    static org.apache.commons.logging.Log log = 
        org.apache.commons.logging.LogFactory.getLog(IntegrityHmacSHA1.class.getName());

   /**
    * Method engineGetURI
    *
    *@inheritDoc
    */
   public abstract String engineGetURI();

   /**
    * Returns the output length of the hash/digest.
    */
   abstract int getDigestLength();

   /** Field _macAlgorithm */
   private Mac _macAlgorithm = null;

   /** Field _HMACOutputLength */
   int _HMACOutputLength = 0;
   private boolean _HMACOutputLengthSet = false;

   /**
    * Method IntegrityHmacSHA1das
    *
    * @throws XMLSignatureException
    */
   public IntegrityHmac() throws XMLSignatureException {

      String algorithmID = JCEMapper.translateURItoJCEID(this.engineGetURI());
      if (log.isDebugEnabled())
      	log.debug("Created IntegrityHmacSHA1 using " + algorithmID);

      try {
         this._macAlgorithm = Mac.getInstance(algorithmID);
      } catch (java.security.NoSuchAlgorithmException ex) {
         Object[] exArgs = { algorithmID,
                             ex.getLocalizedMessage() };

         throw new XMLSignatureException("algorithms.NoSuchAlgorithm", exArgs);
      }
   }

   /**
    * Proxy method for {@link java.security.Signature#setParameter(java.security.spec.AlgorithmParameterSpec)}
    * which is executed on the internal {@link java.security.Signature} object.
    *
    * @param params
    * @throws XMLSignatureException
    */
   protected void engineSetParameter(AlgorithmParameterSpec params)
           throws XMLSignatureException {
      throw new XMLSignatureException("empty");
   }

   public void reset() {
       _HMACOutputLength=0;
       _HMACOutputLengthSet = false;
       this._macAlgorithm.reset();
   }

   /**
    * Proxy method for {@link java.security.Signature#verify(byte[])}
    * which is executed on the internal {@link java.security.Signature} object.
    *
    * @param signature
    * @return true if the signature is correct
    * @throws XMLSignatureException
    */
   protected boolean engineVerify(byte[] signature)
           throws XMLSignatureException {

      try {
         if (this._HMACOutputLengthSet && this._HMACOutputLength < getDigestLength())
{
            if (log.isDebugEnabled()) {
                log.debug("HMACOutputLength must not be less than " + getDigestLength());
            }
            Object[] exArgs = { String.valueOf(getDigestLength()) };
            throw new XMLSignatureException
                ("algorithms.HMACOutputLengthMin", exArgs);
         } else {
            byte[] completeResult = this._macAlgorithm.doFinal();
            return MessageDigestAlgorithm.isEqual(completeResult, signature);
         }
      } catch (IllegalStateException ex) {
         throw new XMLSignatureException("empty", ex);
      }
   }

   /**
    * Proxy method for {@link java.security.Signature#initVerify(java.security.PublicKey)}
    * which is executed on the internal {@link java.security.Signature} object.
    *
    * @param secretKey
    * @throws XMLSignatureException
    */
   protected void engineInitVerify(Key secretKey) throws XMLSignatureException {

      if (!(secretKey instanceof SecretKey)) {
         String supplied = secretKey.getClass().getName();
         String needed = SecretKey.class.getName();
         Object exArgs[] = { supplied, needed };

         throw new XMLSignatureException("algorithms.WrongKeyForThisOperation",
                                         exArgs);
      }

      try {
         this._macAlgorithm.init(secretKey);
      } catch (InvalidKeyException ex) {
            // reinstantiate Mac object to work around bug in JDK
            // see: http://bugs.sun.com/view_bug.do?bug_id=4953555
            Mac mac = this._macAlgorithm;
            try {
                this._macAlgorithm = Mac.getInstance
                    (_macAlgorithm.getAlgorithm());
            } catch (Exception e) {
                // this shouldn't occur, but if it does, restore previous Mac
                if (log.isDebugEnabled()) {
                    log.debug("Exception when reinstantiating Mac:" + e);
                }
                this._macAlgorithm = mac;
            }
            throw new XMLSignatureException("empty", ex);
      }
   }

   /**
    * Proxy method for {@link java.security.Signature#sign()}
    * which is executed on the internal {@link java.security.Signature} object.
    *
    * @return the result of the {@link java.security.Signature#sign()} method
    * @throws XMLSignatureException
    */
   protected byte[] engineSign() throws XMLSignatureException {

      try {
         if (this._HMACOutputLengthSet && this._HMACOutputLength < getDigestLength()) {
            if (log.isDebugEnabled()) {
                log.debug("HMACOutputLength must not be less than " + getDigestLength());
            }
            Object[] exArgs = { String.valueOf(getDigestLength()) };
            throw new XMLSignatureException
                ("algorithms.HMACOutputLengthMin", exArgs);
         } else {
            return this._macAlgorithm.doFinal();
         }
      } catch (IllegalStateException ex) {
         throw new XMLSignatureException("empty", ex);
      }
   }

   /**
    * Method reduceBitLength
    *
    * @param completeResult
    * @return the reduced bits.
    * @param length
    *
    */
   private static byte[] reduceBitLength(byte completeResult[], int length) {

      int bytes = length / 8;
      int abits = length % 8;
      byte[] strippedResult = new byte[bytes + ((abits == 0)
                                                ? 0
                                                : 1)];

      System.arraycopy(completeResult, 0, strippedResult, 0, bytes);

      if (abits > 0) {
         byte[] MASK = { (byte) 0x00, (byte) 0x80, (byte) 0xC0, (byte) 0xE0,
                         (byte) 0xF0, (byte) 0xF8, (byte) 0xFC, (byte) 0xFE };

         strippedResult[bytes] = (byte) (completeResult[bytes] & MASK[abits]);
      }

      return strippedResult;
   }

   /**
    * Method engineInitSign
    *
    * @param secretKey
    * @throws XMLSignatureException
    */
   protected void engineInitSign(Key secretKey) throws XMLSignatureException {

      if (!(secretKey instanceof SecretKey)) {
         String supplied = secretKey.getClass().getName();
         String needed = SecretKey.class.getName();
         Object exArgs[] = { supplied, needed };

         throw new XMLSignatureException("algorithms.WrongKeyForThisOperation",
                                         exArgs);
      }

      try {
         this._macAlgorithm.init(secretKey);
      } catch (InvalidKeyException ex) {
         throw new XMLSignatureException("empty", ex);
      }
   }

   /**
    * Method engineInitSign
    *
    * @param secretKey
    * @param algorithmParameterSpec
    * @throws XMLSignatureException
    */
   protected void engineInitSign(
           Key secretKey, AlgorithmParameterSpec algorithmParameterSpec)
              throws XMLSignatureException {

      if (!(secretKey instanceof SecretKey)) {
         String supplied = secretKey.getClass().getName();
         String needed = SecretKey.class.getName();
         Object exArgs[] = { supplied, needed };

         throw new XMLSignatureException("algorithms.WrongKeyForThisOperation",
                                         exArgs);
      }

      try {
         this._macAlgorithm.init(secretKey, algorithmParameterSpec);
      } catch (InvalidKeyException ex) {
         throw new XMLSignatureException("empty", ex);
      } catch (InvalidAlgorithmParameterException ex) {
         throw new XMLSignatureException("empty", ex);
      }
   }

   /**
    * Method engineInitSign
    *
    * @param secretKey
    * @param secureRandom
    * @throws XMLSignatureException
    */
   protected void engineInitSign(Key secretKey, SecureRandom secureRandom)
           throws XMLSignatureException {
      throw new XMLSignatureException("algorithms.CannotUseSecureRandomOnMAC");
   }

   /**
    * Proxy method for {@link java.security.Signature#update(byte[])}
    * which is executed on the internal {@link java.security.Signature} object.
    *
    * @param input
    * @throws XMLSignatureException
    */
   protected void engineUpdate(byte[] input) throws XMLSignatureException {

      try {
         this._macAlgorithm.update(input);
      } catch (IllegalStateException ex) {
         throw new XMLSignatureException("empty", ex);
      }
   }

   /**
    * Proxy method for {@link java.security.Signature#update(byte)}
    * which is executed on the internal {@link java.security.Signature} object.
    *
    * @param input
    * @throws XMLSignatureException
    */
   protected void engineUpdate(byte input) throws XMLSignatureException {

      try {
         this._macAlgorithm.update(input);
      } catch (IllegalStateException ex) {
         throw new XMLSignatureException("empty", ex);
      }
   }

   /**
    * Proxy method for {@link java.security.Signature#update(byte[], int, int)}
    * which is executed on the internal {@link java.security.Signature} object.
    *
    * @param buf
    * @param offset
    * @param len
    * @throws XMLSignatureException
    */
   protected void engineUpdate(byte buf[], int offset, int len)
           throws XMLSignatureException {

      try {
         this._macAlgorithm.update(buf, offset, len);
      } catch (IllegalStateException ex) {
         throw new XMLSignatureException("empty", ex);
      }
   }

   /**
    * Method engineGetJCEAlgorithmString
    * @inheritDoc
    *
    */
   protected String engineGetJCEAlgorithmString() {

      log.debug("engineGetJCEAlgorithmString()");

      return this._macAlgorithm.getAlgorithm();
   }

   /**
    * Method engineGetJCEAlgorithmString
    *
    * @inheritDoc
    */
   protected String engineGetJCEProviderName() {
      return this._macAlgorithm.getProvider().getName();
   }

   /**
    * Method engineSetHMACOutputLength
    *
    * @param HMACOutputLength
    */
   protected void engineSetHMACOutputLength(int HMACOutputLength) {
      this._HMACOutputLength = HMACOutputLength;
      this._HMACOutputLengthSet = true;
   }

   /**
    * Method engineGetContextFromElement
    *
    * @param element
    */
   protected void engineGetContextFromElement(Element element) {

      super.engineGetContextFromElement(element);

      if (element == null) {
         throw new IllegalArgumentException("element null");
      }

      Text hmaclength =XMLUtils.selectDsNodeText(element.getFirstChild(),
         Constants._TAG_HMACOUTPUTLENGTH,0);               

      if (hmaclength != null) {
         this._HMACOutputLength = Integer.parseInt(hmaclength.getData());
         this._HMACOutputLengthSet = true;
      }
   }

   /**
    * Method engineAddContextToElement
    *
    * @param element
    */
   public void engineAddContextToElement(Element element) {

      if (element == null) {
         throw new IllegalArgumentException("null element");
      }

      if (this._HMACOutputLengthSet) {
         Document doc = element.getOwnerDocument();
         Element HMElem = XMLUtils.createElementInSignatureSpace(doc,
                             Constants._TAG_HMACOUTPUTLENGTH);
         Text HMText =
            doc.createTextNode(new Integer(this._HMACOutputLength).toString());

         HMElem.appendChild(HMText);
         XMLUtils.addReturnToElement(element);
         element.appendChild(HMElem);
         XMLUtils.addReturnToElement(element);
      }
   }

   /**
    * Class IntegrityHmacSHA1
    *
    * @author $Author: mullan $
    * @version $Revision: 794013 $
    */
   public static class IntegrityHmacSHA1 extends IntegrityHmac {

      /**
       * Constructor IntegrityHmacSHA1
       *
       * @throws XMLSignatureException
       */
      public IntegrityHmacSHA1() throws XMLSignatureException {
         super();
      }

      /**
       * Method engineGetURI
       * @inheritDoc
       *
       */
      public String engineGetURI() {
         return XMLSignature.ALGO_ID_MAC_HMAC_SHA1;
      }

      int getDigestLength() {
          return 160;
      }
   }

   /**
    * Class IntegrityHmacSHA256
    *
    * @author $Author: mullan $
    * @version $Revision: 794013 $
    */
   public static class IntegrityHmacSHA256 extends IntegrityHmac {

      /**
       * Constructor IntegrityHmacSHA256
       *
       * @throws XMLSignatureException
       */
      public IntegrityHmacSHA256() throws XMLSignatureException {
         super();
      }

      /**
       * Method engineGetURI
       *
       * @inheritDoc
       */
      public String engineGetURI() {
         return XMLSignature.ALGO_ID_MAC_HMAC_SHA256;
      }

      int getDigestLength() {
          return 256;
      }
   }

   /**
    * Class IntegrityHmacSHA384
    *
    * @author $Author: mullan $
    * @version $Revision: 794013 $
    */
   public static class IntegrityHmacSHA384 extends IntegrityHmac {

      /**
       * Constructor IntegrityHmacSHA384
       *
       * @throws XMLSignatureException
       */
      public IntegrityHmacSHA384() throws XMLSignatureException {
         super();
      }

      /**
       * Method engineGetURI
       * @inheritDoc
       *
       */
      public String engineGetURI() {
         return XMLSignature.ALGO_ID_MAC_HMAC_SHA384;
      }

      int getDigestLength() {
          return 384;
      }
   }

   /**
    * Class IntegrityHmacSHA512
    *
    * @author $Author: mullan $
    * @version $Revision: 794013 $
    */
   public static class IntegrityHmacSHA512 extends IntegrityHmac {

      /**
       * Constructor IntegrityHmacSHA512
       *
       * @throws XMLSignatureException
       */
      public IntegrityHmacSHA512() throws XMLSignatureException {
         super();
      }

      /**
       * Method engineGetURI
       * @inheritDoc
       *
       */
      public String engineGetURI() {
         return XMLSignature.ALGO_ID_MAC_HMAC_SHA512;
      }

      int getDigestLength() {
          return 512;
      }
   }

   /**
    * Class IntegrityHmacRIPEMD160
    *
    * @author $Author: mullan $
    * @version $Revision: 794013 $
    */
   public static class IntegrityHmacRIPEMD160 extends IntegrityHmac {

      /**
       * Constructor IntegrityHmacRIPEMD160
       *
       * @throws XMLSignatureException
       */
      public IntegrityHmacRIPEMD160() throws XMLSignatureException {
         super();
      }

      /**
       * Method engineGetURI
       *
       * @inheritDoc
       */
      public String engineGetURI() {
         return XMLSignature.ALGO_ID_MAC_HMAC_RIPEMD160;
      }

      int getDigestLength() {
          return 160;
      }
   }

   /**
    * Class IntegrityHmacMD5
    *
    * @author $Author: mullan $
    * @version $Revision: 794013 $
    */
   public static class IntegrityHmacMD5 extends IntegrityHmac {

      /**
       * Constructor IntegrityHmacMD5
       *
       * @throws XMLSignatureException
       */
      public IntegrityHmacMD5() throws XMLSignatureException {
         super();
      }

      /**
       * Method engineGetURI
       *
       * @inheritDoc
       */
      public String engineGetURI() {
         return XMLSignature.ALGO_ID_MAC_HMAC_NOT_RECOMMENDED_MD5;
      }

      int getDigestLength() {
          return 128;
      }
   }
}
