使用AES的Java卡加密返回6F00

Question

我对Java卡编程很陌生。我看到了一个关于针对Java卡的AES加密方法的例子，并且能够创建和安装applet。当我试图与applet通信时，它会返回一个6F00错误消息。我做错了什么？

下面是我的代码示例：

private void SendData(APDU apdu) 
{

    aesKeyTrial= (AESKey) KeyBuilder.buildKey(KeyBuilder.TYPE_AES, KeyBuilder.LENGTH_AES_128, false);
    byte[] outBuffer;
    outBuffer = new byte[16];
    byte[] trialKey;
    trialKey = new byte[16];
    byte[] input = {(byte)0x44,(byte)0x22,(byte)0x33,(byte)0x44,(byte)0x55,(byte)0x66,(byte)0x77,(byte)0x88,(byte)0x99,0x10,(byte)0xA2, 0x35, (byte)0x5E,0x15,0x16,0x14};
    byte[] key = {0x2d, 0x2a, 0x2d, 0x42, 0x55, 0x49, 0x4c, 0x44, 0x41, 0x43, 0x4f, 0x44, 0x45, 0x2d, 0x2a, 0x2d};
    byte[] buffer = apdu.getBuffer();
    short len = (short) input.length;


    aesKeyTrial.setKey(trialKey,(short)0);
    if(len<=0||len%16!=0)
    {
        ISOException.throwIt(ISO7816.SW_WRONG_LENGTH);
    }
    aesCipher = Cipher.getInstance(Cipher.ALG_AES_BLOCK_128_CBC_NOPAD, false);
    aesCipher.init(aesKeyTrial, Cipher.MODE_ENCRYPT);
    aesCipher.doFinal(input, ISO7816.OFFSET_CDATA, len, outBuffer, (short)0); 
    Util.arrayCopyNonAtomic(input, (short)0, buffer, (short)0, (short)len);
    apdu.setOutgoing();
    apdu.setOutgoingLength(len);
    apdu.sendBytes((short) 0, (short)len);
}

我想加密的是“输入”。

Answer 1

正如您在回答中所说的，代码的问题在于您向doFinal (byte[] inBuff, short inOffset, short inLength,byte[] outBuff, short outOffset)方法传递了错误的参数。

但是，您正在使用的示例代码看起来非常糟糕。我认为这是写得不好的原因：

它在一个被多次调用的方法中使用了动态变量。动态变量是使用new关键字创建的变量。这些变量将在EEPROM中分配。在EEPROM中转换确实比RAM慢，而且它在磨损之前也有一个有限的擦除操作，因此强烈建议在不需要在不同的CAD (读卡器)会话之间共享数据的情况下使用RAM而不是EEPROM。另外，由于Java Card中没有强制/自动垃圾收集器，所以不要重复定义不同的动态变量，而是使用一个全局变量(类变量或实例变量而不是局部变量)。

2-由于int数据类型在JavaCards中是可选的，因此必须尽可能多地使用short和byte，还需要将所有值转换为这些类型，以防止有符号/无符号问题。

最后，我向您提供了您的程序的升级版本：

package soQusetion;

import javacard.framework.*;
import javacard.security.AESKey;
import javacard.security.KeyBuilder;
import javacardx.crypto.Cipher;

public class SOQ1 extends Applet {

    Cipher aesCipher;
    AESKey aesKey;

    //Two different types of memory for different usage. each one has 16 (= 0x10) byte capacity.
    private byte[] volatileMem;
    private byte[] nonVolatileMem;

    //INS value for APDU command
    public static final byte INS_SET_KEY = 0x10;
    public static final byte INS_ENCRYPT = 0x20;
    public static final byte INS_DECRYPT = 0x30;

    public static void install(byte[] bArray, short bOffset, byte bLength) {
        new SOQ1();
    }

    protected SOQ1() {
        volatileMem = JCSystem.makeTransientByteArray((short) 0x10, JCSystem.CLEAR_ON_DESELECT);
        nonVolatileMem = new byte[(short) 0x10];
        aesCipher = Cipher.getInstance(Cipher.ALG_AES_BLOCK_128_ECB_NOPAD, false);
        aesKey = (AESKey) KeyBuilder.buildKey(KeyBuilder.TYPE_AES, KeyBuilder.LENGTH_AES_128, false);
        register();
    }

    public void process(APDU apdu) {
        if (selectingApplet()) {
            return;
        }
        byte[] buffer = apdu.getBuffer();
        apdu.setIncomingAndReceive();

        if (buffer[ISO7816.OFFSET_LC] != (byte) 0x10) {
            ISOException.throwIt(ISO7816.SW_WRONG_LENGTH);
        }

        switch (buffer[ISO7816.OFFSET_INS]) {
            case INS_SET_KEY:
                aesKey.setKey(buffer, ISO7816.OFFSET_CDATA);
                break;
            case INS_ENCRYPT:
                aesCipher.init(aesKey, Cipher.MODE_ENCRYPT);
                aesCipher.doFinal(buffer, ISO7816.OFFSET_CDATA, (short) 0x10, volatileMem, (short) 0x00);
                Util.arrayCopyNonAtomic(volatileMem, (short) 0x00, buffer, (short) 0x00, (short) 0x10);
                apdu.setOutgoingAndSend((short) 0x00, (short) 0x10);
                break;
            case INS_DECRYPT:
                aesCipher.init(aesKey, Cipher.MODE_DECRYPT);
                aesCipher.doFinal(buffer, ISO7816.OFFSET_CDATA, (short) 0x10, volatileMem, (short) 0x00);
                Util.arrayCopyNonAtomic(volatileMem, (short) 0x00, buffer, (short) 0x00, (short) 0x10);
                apdu.setOutgoingAndSend((short) 0x00, (short) 0x10);
                break;
            default:
                ISOException.throwIt(ISO7816.SW_INS_NOT_SUPPORTED);
        }

    }
}

它的工作如下：

Select Applet begin...
Select Applet successful.
//Loading AES Key APDU Command
Send: 00 10 00 00 10 00 11 22 33 44 55 66 77 88 99 AA BB CC DD EE FF 00
Recv: 90 00
//Encrypt APDU Command
Send: 00 20 00 00 10 00 11 22 33 44 55 66 77 88 99 AA BB CC DD EE FF 00
Recv: 62 F6 79 BE 2B F0 D9 31 64 1E 03 9C A3 40 1B B2 90 00
//Decrypt APDU Command
Send: 00 30 00 00 10 62 F6 79 BE 2B F0 D9 31 64 1E 03 9C A3 40 1B B2 00
Recv: 00 11 22 33 44 55 66 77 88 99 AA BB CC DD EE FF 90 00

任何使上述程序更有效的建议，我都欢迎。

Answer 2

嗨，我发现我的错误是什么，或者我的代码有什么问题。我误解了函数doFinal，它混淆了在卡中安装的内容。

下面是新的、干净的代码：

Cipher aesCipher;
  AESKey aesKeyTrial;
  aesKeyTrial= (AESKey) KeyBuilder.buildKey(KeyBuilder.TYPE_AES_TRANSIENT_DESELECT, KeyBuilder.LENGTH_AES_128, false);
  byte[] buffer = apdu.getBuffer();
  byte[] aesKey;
  aesKey = new byte[16];
  byte[] input = {(byte)0x11,(byte)0x22,(byte)0x33,(byte)0x44,(byte)0x55,(byte)0x66,(byte)0x77,(byte)0x88,(byte)0x99,0x10,(byte)0xA2, 0x35, (byte)0x5E,0x15,0x16,0x14};
  byte[] key = {0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26};

  short len = (short) input.length;
  if (len <= 0 || len % 16 != 0)
    {
        ISOException.throwIt(ISO7816.SW_WRONG_LENGTH);
    }

  aesKeyTrial.setKey(key,(short)0);
  aesCipher = Cipher.getInstance(Cipher.ALG_AES_BLOCK_128_ECB_NOPAD, false);
  aesCipher.init(aesKeyTrial, Cipher.MODE_ENCRYPT); 
  aesCipher.doFinal(input, (short)0, len, buffer, (short)0);
  apdu.setOutgoingAndSend((short)0, len);