package mit.Rijndael;
import java.security.*;

public final class CBC {
    boolean doEncrypt;
    private byte [] iv;
    Object sessionkey;

    public CBC(byte [] key, boolean doEncrypt, byte [] iv) throws InvalidKeyException {
	this.doEncrypt = doEncrypt;
	this.iv = iv;
	sessionkey = Rijndael_Algorithm.makeKey(key);
    }

    public byte [] CBCcrypt(byte [] in) throws InvalidParameterException {
	
      if (iv == null) {
	throw new InvalidParameterException("null iv");
      }

      iv = (byte []) iv.clone();
      if (doEncrypt)
	  in = PAD.doPad(in);
      
      int inlen = in.length;
      int blocks = in.length / 16;

      byte [] out = new byte[in.length];
      int i;
      int b;
      for (b = 0; b < blocks; b++) {
	if (doEncrypt) {
	  for (i = 0; i < 16; i++) iv[i] ^= in[b*16+i];
	  byte [] temp = Rijndael_Algorithm.blockEncrypt(iv, 0, sessionkey);
	  System.arraycopy(temp, 0, iv, 0, 16);
	  System.arraycopy(temp, 0, out, b*16, 16);
	} else {
	  byte [] temp = Rijndael_Algorithm.blockDecrypt(in, b*16, sessionkey);
	  for (i = 0; i < 16; i++ )
	    out[b*16+i] = (byte) (temp[i] ^ iv[i]);
	  System.arraycopy(in, b*16, iv, 0, 16);
	}
      }

      if (!doEncrypt)
	  out = PAD.unPad(out);

      return (out);
    }
}