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 package org.apidesign.impl.security.extension;

 import org.apidesign.api.security.Digest;

 import java.nio.ByteBuffer;

 import java.security.MessageDigest;

 import java.security.NoSuchAlgorithmException;

 import java.security.Provider;

 import java.security.Security;

 import java.util.Collections;

 import java.util.List;

 import java.util.Map;

 /**

  *

  * @author Jaroslav Tulach <jaroslav.tulach@apidesign.org>

  */

 public class BridgeToOld extends Provider {

     public BridgeToOld() {

         super("spi.Digestor", 1.0, "");

         Security.addProvider(this);

     }

     @Override

     public synchronized Service getService(String type, String algorithm) {

         if ("MessageDigest".equals(type)) {

             Digest dig = Digest.getInstance(algorithm);

             if (dig != null) {

                 return new ServiceImpl(dig, this, type, algorithm, "", Collections.<String>emptyList(), Collections.<String,String>emptyMap());

             }

         }

         return null;

     }

     private static class ServiceImpl<Data> extends Service {

         Digest dig;

         public ServiceImpl(Digest dig, Provider provider, String type, String algorithm, String className, List<String> aliases, Map<String, String> attributes) {

             super(provider, type, algorithm, className, aliases, attributes);

             this.dig = dig;

         }

         @Override

         public Object newInstance(Object constructorParameter) throws NoSuchAlgorithmException {

             return new MessageDigest(getAlgorithm()) {

                 private byte[] res;

                 @Override

                 protected void engineUpdate(byte input) {

                     ByteBuffer bb = ByteBuffer.wrap(new byte[] { input });

                     res = dig.digest(bb);

                 }

                 @Override

                 protected void engineUpdate(byte[] input, int offset, int len) {

                     ByteBuffer bb = ByteBuffer.wrap(input);

                     bb.position(offset);

                     bb.limit(offset + len);

                     res = dig.digest(bb);

                 }

                 @Override

                 protected byte[] engineDigest() {

                     return res;

                 }

                 @Override

                 protected void engineReset() {

                     dig = Digest.getInstance(getAlgorithm());

                 }

             };

         }

     }

 }