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JCOSecretKey.java

package edu.virtualschool.jco;

import java.security.SecureRandom;

import org.bouncycastle.crypto.engines.RC4Engine;
import org.bouncycastle.crypto.params.KeyParameter;

import edu.virtualschool.jwaa.RuntimeFault;

public class JCOSecretKey extends JCOSymmetricKey
{
  final static int DEFAULT_KEY_LENGTH = 128/8; 
  final static int MINIMUM_KEY_LENGTH = 40/8; 
  final static int MAXIMUM_KEY_LENGTH = 2048/8; 
  
  public JCOSecretKey()
  {
    super(makeKeyParameter(DEFAULT_KEY_LENGTH));
  }
  public JCOSecretKey(int keyLengthInBytes) throws RuntimeFault
  {
    super(makeKeyParameter(keyLengthInBytes));
  }
  final static KeyParameter makeKeyParameter(int keyLengthInBytes)
    throws RuntimeFault
  {
    if (keyLengthInBytes < MINIMUM_KEY_LENGTH || keyLengthInBytes > MAXIMUM_KEY_LENGTH)
      throw new RuntimeFault("keylength " + keyLengthInBytes+ " must be "+MINIMUM_KEY_LENGTH+" to "+MAXIMUM_KEY_LENGTH+" bytes");
    SecureRandom random = new SecureRandom();
    byte[] randomBytes = new byte[keyLengthInBytes];
    random.nextBytes(randomBytes);
    return new KeyParameter(randomBytes);
  }
  public JCOSecretKey(String string)
  {
    this(JCOBase64.decode(string));
  }
  public JCOSecretKey(byte[] bytes)
  {
    super(new KeyParameter(bytes));
  }
  public final byte[] decryptBytes(byte[] inputBytes)
  {
    RC4Engine engine = new RC4Engine();
    engine.init(true, key);
    byte[]  outputBytes = new byte[inputBytes.length];
    engine.processBytes(inputBytes, 0, inputBytes.length, outputBytes, 0);
    return outputBytes;
  }
  public final byte[] encryptBytes(byte[] inputBytes)
  {
    return decryptBytes(inputBytes);
  }
  public final String getAlgorithm()
  {
    return "RC4"; 
  }
  public final String getFormat()
  {
    return "RAW";
  }
}