RSACipher.java

/*********************************************************************************
 *  TotalCross Software Development Kit                                          *
 *  Copyright (C) 2000-2012 SuperWaba Ltda.                                      *
 *  All Rights Reserved                                                          *
 *                                                                               *
 *  This library and virtual machine is distributed in the hope that it will     *
 *  be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of    *
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.                         *
 *                                                                               *
 *********************************************************************************/

package totalcross.crypto.cipher;

import java.math.BigInteger;
import java.security.*;
import java.security.spec.*;
import javax.crypto.spec.IvParameterSpec;
import totalcross.crypto.*;
import totalcross.crypto.NoSuchAlgorithmException;

/**
 * This class implements the RSA cryptographic cipher.
 */
public class RSACipher extends Cipher
{
   /**
    * Returns the name of the algorithm.
    * 
    * @return "RSA".
    */
   public final String getAlgorithm()
   {
      return "RSA";
   }

   /**
    * Returns the block length.
    * 
    * @return Always returns 0.
    */
   public final int getBlockLength()
   {
      return 0;
   }
   
   protected final void doReset() throws NoSuchAlgorithmException, CryptoException
   {
      String transf = "RSA";
      switch (chaining)
      {
         case CHAINING_NONE:
            transf += "/NONE";
            break;
         case CHAINING_ECB:
            transf += "/ECB";
            break;
         case CHAINING_CBC:
            transf += "/CBC";
            break;
      }
      switch (padding)
      {
         case PADDING_NONE:
            transf += "/NoPadding";
            break;
         case PADDING_PKCS1:
            transf += "/PKCS1Padding";
            break;
         case PADDING_PKCS5:
            transf += "/PKCS5Padding";
      }
      
      try
      {
         javax.crypto.Cipher cipher = javax.crypto.Cipher.getInstance(transf);
         cipherRef = cipher;
         
         KeyFactory factory = KeyFactory.getInstance("RSA");
         if (operation == OPERATION_ENCRYPT)
         {
            RSAPublicKey pubKey = (RSAPublicKey)key;
            keyRef = factory.generatePublic(new RSAPublicKeySpec(new BigInteger(pubKey.getModulus()), new BigInteger(pubKey.getPublicExponent())));
         }
         else // DECRYPT
         {
            RSAPrivateKey privKey = (RSAPrivateKey)key;
            keyRef = factory.generatePrivate(new RSAPrivateKeySpec(new BigInteger(privKey.getModulus()), new BigInteger(privKey.getPrivateExponent())));
         }
         
         int mode = operation == OPERATION_ENCRYPT ? javax.crypto.Cipher.ENCRYPT_MODE : javax.crypto.Cipher.DECRYPT_MODE;
         cipher.init(mode, (java.security.Key)keyRef, iv == null ? null : new IvParameterSpec(iv));
         if (iv == null)
            iv = cipher.getIV();
      }
      catch (java.security.NoSuchAlgorithmException e)
      {
         throw new NoSuchAlgorithmException(e.getMessage());
      }      
      catch (GeneralSecurityException e)
      {
         throw new CryptoException(e.getMessage());
      }
   }

   protected final byte[] process(byte[] data) throws CryptoException
   {
      try
      {
         javax.crypto.Cipher cipher = (javax.crypto.Cipher)cipherRef;
         return cipher.doFinal(data);
      }
      catch (GeneralSecurityException e)
      {
         throw new CryptoException(e.getMessage());
      }
   }
   
   protected final boolean isKeySupported(Key key, int operation)
   {
      return (operation == OPERATION_ENCRYPT && key instanceof RSAPublicKey) || (operation == OPERATION_DECRYPT && key instanceof RSAPrivateKey);
   }
   
   protected final boolean isChainingSupported(int chaining)
   {
      return chaining == CHAINING_ECB;
   }
   
   protected final boolean isPaddingSupported(int padding)
   {
      return padding == PADDING_PKCS1;
   }
}