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  package org.apache.cayenne.crypto.cipher;
  
  import java.security.NoSuchAlgorithmException;
  import java.util.Map;
  
  import javax.crypto.Cipher;
  import javax.crypto.NoSuchPaddingException;
  
  import org.apache.cayenne.crypto.CayenneCryptoException;
  import org.apache.cayenne.crypto.CryptoConstants;
  import org.apache.cayenne.di.Inject;
  
  /**
   * Creates and returns a new {@link Cipher} configured using properties from
   * {@link CryptoConstants#PROPERTIES_MAP}.
   * 
   * @since 4.0
   */
  public class DefaultCipherFactory implements CipherFactory {
  
      protected String transformation;
      protected int blockSize;
  
      public DefaultCipherFactory(@Inject(CryptoConstants.PROPERTIES_MAP) Map<String, String> properties) {
          String algorithm = properties.get(CryptoConstants.CIPHER_ALGORITHM);
  
          if (algorithm == null) {
              throw new CayenneCryptoException("Cipher algorithm is not set. Property name: "
                      + CryptoConstants.CIPHER_ALGORITHM);
          }
  
          String mode = properties.get(CryptoConstants.CIPHER_MODE);
          if (mode == null) {
              throw new CayenneCryptoException("Cipher mode is not set. Property name: " + CryptoConstants.CIPHER_MODE);
          }
  
          String padding = properties.get(CryptoConstants.CIPHER_PADDING);
          if (padding == null) {
              throw new CayenneCryptoException("Cipher padding is not set. Property name: "
                      + CryptoConstants.CIPHER_PADDING);
          }
  
          this.transformation = algorithm + "/" + mode + "/" + padding;
      }
  
      @Override
      public Cipher cipher() {
          try {
              return Cipher.getInstance(transformation);
          } catch (NoSuchAlgorithmException e) {
              throw new CayenneCryptoException("Error instantiating a cipher - no such algorithm: " + transformation, e);
          } catch (NoSuchPaddingException e) {
              throw new CayenneCryptoException("Error instantiating a cipher - no such padding: " + transformation, e);
          }
      }
  
      @Override
      public int blockSize() {
  
          // lazy init to prevent Cipher initialization in constructor.
          // synchronization is not required - if we do it multiple times ,
          // shouldn't be a big deal...
          if (blockSize == 0) {
              this.blockSize = cipher().getBlockSize();
          }
  
          return blockSize;
      }
  }
  