用Javacard语句生成动态口令

生成动态口令的Javacard代码如下：

package com.example;

import javacard.framework.*;
import javacard.security.HMACKey;
import javacard.security.KeyBuilder;
import javacard.security.MessageDigest;
import javacardx.crypto.Cipher;

public class OTPApplet extends Applet {

    private static final byte CLA_OTP = (byte) 0xB0;
    private static final byte INS_GENERATE = (byte) 0x10;

    private static final short OTP_LENGTH = 6;
    private static final short KEY_LENGTH = 16;
    private static final short DIGEST_LENGTH = 20;

    private MessageDigest md;
    private HMACKey key;
    private Cipher cipher;

    private byte[] otp;
    private byte[] hash;

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

    private OTPApplet() {
        md = MessageDigest.getInstance(MessageDigest.ALG_SHA, false);
        key = (HMACKey) KeyBuilder.buildKey(KeyBuilder.TYPE_HMAC_TRANSIENT_DESELECT, KEY_LENGTH, false);
        cipher = Cipher.getInstance(Cipher.ALG_AES_BLOCK_128_CBC_NOPAD, false);
        otp = JCSystem.makeTransientByteArray(OTP_LENGTH, JCSystem.CLEAR_ON_RESET);
        hash = JCSystem.makeTransientByteArray(DIGEST_LENGTH, JCSystem.CLEAR_ON_RESET);
    }

    public void process(APDU apdu) {
        if (selectingApplet()) {
            return;
        }

        byte[] buffer = apdu.getBuffer();
        if (buffer[ISO7816.OFFSET_CLA] != CLA_OTP) {
            ISOException.throwIt(ISO7816.SW_CLA_NOT_SUPPORTED);
        }

        switch (buffer[ISO7816.OFFSET_INS]) {
            case INS_GENERATE:
                generateOTP(apdu);
                break;
            default:
                ISOException.throwIt(ISO7816.SW_INS_NOT_SUPPORTED);
        }
    }

    private void generateOTP(APDU apdu) {
        byte[] buffer = apdu.getBuffer();

        byte[] secret = new byte[KEY_LENGTH];
        Util.arrayCopy(buffer, ISO7816.OFFSET_CDATA, secret, (short) 0, KEY_LENGTH);

        byte[] counter = new byte[8];
        Util.arrayCopy(buffer, (short) (ISO7816.OFFSET_CDATA + KEY_LENGTH), counter, (short) 0, (short) 8);

        md.reset();
        md.doFinal(secret, (short) 0, KEY_LENGTH, hash, (short) 0);

        for (int i = 0; i < 4; i++) {
            counter[i + 4] = (byte) (counter[i + 4] ^ 0xFF);
        }

        key.setKey(hash, (short) 0);
        cipher.init(key, Cipher.MODE_ENCRYPT);

        byte[] input = new byte[16];
        Util.arrayCopy(counter, (short) 0, input, (short) 0, (short) 8);
        cipher.update(input, (short) 0, (short) 16, input, (short) 0);

        for (int i = 0; i < OTP_LENGTH; i++) {
            otp[i] = (byte) (input[i] & 0x7F);
        }

        Util.setShort(buffer, (short) 0, OTP_LENGTH);
        Util.arrayCopy(otp, (short) 0, buffer, (short) 2, OTP_LENGTH);
        apdu.setOutgoingAndSend((short) 0, (short) (OTP_LENGTH + 2));
    }
}

这段代码实现了一个简单的OTP（One-time Password）生成应用程序。它使用SHA-1哈希算法和HMAC-SHA1消息认证码（MAC）算法生成动态口令。首先，应用程序接收到一个由16字节的共享密钥和8字节的计数器组成的输入数据。然后，它使用共享密钥计算HMAC，并将计数器的后4个字节与0xFF异或。接下来，它使用AES算法对16字节的输入数据进行加密，并从加密结果中提取6字节的OTP。最后，它将OTP作为响应发送给客户端。

要使用这个应用程序生成动态口令，你需要将共享密钥和计数器作为输入数据发送到应用程序。应用程序将返回一个6字节的OTP作为响应。你可以使用以下示例代码来与这个应用程序通信：

import javax.smartcardio.*;

public class OTPClient {

    private static final byte[] AID = {(byte) 0xA0, 0x00, 0x00, 0x00, 0x62, 0x03, 0x01, 0x08, 0x01};

    public static void main(String[] args) throws CardException {
        TerminalFactory factory = TerminalFactory.getDefault();
        CardTerminal terminal = factory.terminals().list().get(0);

        Card card = terminal.connect("*");
        CardChannel channel = card.getBasicChannel();

        byte[] key = {(byte) 0x01, (byte) 0x23, (byte) 0x45, (byte) 0x67, (byte) 0x89, (byte) 0xAB, (byte) 0xCD, (byte) 0xEF};
        byte[] counter = {(byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x01};

        CommandAPDU command = new CommandAPDU(AID, (byte) 0xB0, (byte) 0x10, (byte) 0x00, key, (short) 0, (short) key.length);
        ResponseAPDU response = channel.transmit(command);

        while (response.getSW() == 0x9000) {
            byte[] otp = response.getData();
            System.out.println(String.format("%06d", ((otp[0] & 0xFF) << 16) | ((otp[1] & 0xFF) << 8) | (otp[2] & 0xFF)));

            command = new CommandAPDU(AID, (byte) 0xB0, (byte) 0x10, (byte) 0x00, counter, (short) 0, (short) counter.length);
            response = channel.transmit(command);

            counter[7]++;
        }

        card.disconnect(false);
    }
}

这个示例代码使用javax.smartcardio库与Javacard应用程序通信。它发送一个由共享密钥和计数器组成的APDU命令，并接收应用程序返回的OTP。它使用一个简单的循环来生成多个OTP，每次递增计数器的最后一个字节。