Java Card Applet在尝试加密消息时返回6f00

Question

我正在尝试加密导入卡中的密钥，并将其再次存储在同一字节数组中。下面的import_key函数接收一个apdu并提取消息key，然后尝试对其进行加密（简单DES加密）并将其存储在同一位置。似乎我已经做了所有必要的事情，但不幸的是，每次我取消注释加密部分时，我都会收到6f00！！！这是我的代码：

public class Encryptor extends Applet {
private byte[] KEY                                  = new byte[128];
private byte key_len                                = (byte)0;
private byte[] ENC_KEY                              = new byte[32];
private byte enc_key_len                            = (byte)0;
Cipher MyCipher;
private byte[] TheDES_Key = new byte[24];
DESKey MyDES1Key = (DESKey) KeyBuilder.buildKey(KeyBuilder.TYPE_DES,KeyBuilder.LENGTH_DES, false);
byte ConfiguredKeyLength = 0;
{...}
private void import_key(APDU apdu) {
    byte[] buffer = new byte[maximum_buffer_len];
    buffer = apdu.getBuffer();
    key_len = buffer[ISO7816.OFFSET_LC];
    apdu.setIncomingAndReceive();
    Util.arrayCopy(buffer, (short) (ISO7816.OFFSET_CDATA), KEY, (short) 0, (short) key_len);
    Util.arrayCopyNonAtomic(ENC_KEY, (short) 0, TheDES_Key, (short) 0, (short) enc_key_len);
    MyDES1Key.setKey(TheDES_Key, (short) 0);
    MyCipher.init(MyDES1Key, Cipher.MODE_ENCRYPT);
    byte[] CipheredData = JCSystem.makeTransientByteArray((short) 32,JCSystem.CLEAR_ON_DESELECT);
    MyCipher.doFinal(KEY, (short)0,(short)key_len,CipheredData,(short)0);
    Util.arrayCopyNonAtomic(CipheredData,(short)0,KEY,(short)0,(short)key_len);
    return;
    }
}

Answer 1

在行中：

DESKey MyDES1Key = (DESKey) KeyBuilder.buildKey(KeyBuilder.TYPE_DES,KeyBuilder.LENGTH_DES, false);

您将MyDES1Key的长度定义为LENGTH_DES，即8字节，而在行中：

MyDES1Key.setKey(TheDES_Key, (short) 0);

您正在使用24字节变量填充它！

换句话说，必须将KeyBuilder.LENGTH_DES替换为KeyBuilder.LENGTH_DES3_3KEY。