Java Card Applet 在尝试加密消息时返回 6f00

Question

我正在尝试加密我卡中导入的密钥并将其再次存储在同一个字节数组中。 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，每次我取消加密部分的注释时我都会收到 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

行内：

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，而在该行中：

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

您正在用 24 字节变量填充它！

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