如何将ATQA和SEL发送到Mifare Classic 1k

Question

根据文档，在发生读/写之前，我需要先发送REQA，然后发送SELECT，以防冲突。但是我找不到任何完整的示例代码，执行此操作的代码序列。每个人都从authenticate中的onTagDiscovered开始，然后开始读取/写入。

所以我的问题是，1. Android是否在后台自行执行自己的REQA / SEL？2.如果我愿意，如何独自执行REQA和SEL？

我基于代码here提出了一个示例代码

try {
            byte[] reqa = new byte[1];
            reqa[0] = 0x26;
            Log.e(TAG, "Sending REQA: " + bytesToHex(reqa));
            mifareTag.transceive(reqa);                
            Log.e(TAG, bytesToHex(mifareTag.transceive(reqa)));

            byte[] sel = new byte[9];
            sel[0] = (byte) 0x93;
            sel[1] = (byte) 0x70;
            System.arraycopy(uid, uid.length - 4, sel, 2, 4);
            sel[6] = (byte) (sel[2] ^ sel[3] ^ sel[4] ^ sel[5]);

            java.util.zip.CRC32 x = new java.util.zip.CRC32();
            x.update(sel);
            long crc32 = x.getValue();

            sel[7] = (byte) crc32;
            sel[8] = (byte) (crc32 >> 8);

            Log.e(TAG, "CRC: " + Long.toHexString(crc32));
            Log.e(TAG, "Sending SEL: " + bytesToHex(sel));

            Log.e(TAG, bytesToHex(mifareTag.transceive(sel)));
            if (mifareTag.transceive(cmd) != null) {
                Log.e(TAG, "NfcA Tag transcieve:auth success");
                return true;
            }
        } catch (Exception ex) {
            Log.e(TAG, "NfcA Tag transcieve:auth failed with exception !", ex);
            return false;
        }

但是问题是，通过这段代码，我收到的是奇怪的数据。

10-22 11:04:13.465 30687-30734/com.mfreader E/RfidReader: Sending REQA: 26
10-22 11:04:13.492 30687-30734/com.mfreader E/RfidReader: B2007D9BD20804000215671E0D8B811D
10-22 11:04:13.492 30687-30734/com.mfreader E/RfidReader: CRC: a247ff86
10-22 11:04:13.493 30687-30734/com.mfreader E/RfidReader: Sending SEL: 93701A2E7D9BD286FF
10-22 11:04:13.519 30687-30734/com.mfreader E/RfidReader: B2007D9BD20804000215671E0D8B811D
10-22 11:04:13.602 30687-30734/com.mfreader E/RfidReader: NfcA Tag transcieve:auth failed with exception !
    java.io.IOException: Transceive failed
        at android.nfc.TransceiveResult.getResponseOrThrow(TransceiveResult.java:52)
        at android.nfc.tech.BasicTagTechnology.transceive(BasicTagTechnology.java:151)
        at android.nfc.tech.NfcA.transceive(NfcA.java:145)

返回的值是Sect#0Block#0，但前2个字节用UID的B200代替1A2E。并且后续的Auth失败，否则只会间歇性失败（这是我要解决的问题！）！

不确定我在做什么错，有帮助吗？

Answer 1

1. Android是否在幕后自行执行自己的REQA / SEL？

是

2. 如果愿意，我如何自己执行REQA和SEL？

  /**
 * Send raw NFC-A commands to the tag and receive the response.
 *
 * <p>Applications must not append the EoD (CRC) to the payload,
 * it will be automatically calculated.
 * <p>Applications must only send commands that are complete bytes,
 * for example a SENS_REQ is not possible (these are used to
 * manage tag polling and initialization).
 *
 * <p>Use {@link #getMaxTransceiveLength} to retrieve the maximum number of bytes
 * that can be sent with {@link #transceive}.
 *
 * <p>This is an I/O operation and will block until complete. It must
 * not be called from the main application thread. A blocked call will be canceled with
 * {@link IOException} if {@link #close} is called from another thread.
 *
 * <p class="note">Requires the {@link android.Manifest.permission#NFC} permission.
 *
 * @param data bytes to send
 * @return bytes received in response
 * @throws TagLostException if the tag leaves the field
 * @throws IOException if there is an I/O failure, or this operation is canceled
 */
public byte[] transceive(byte[] data) throws IOException {
    return transceive(data, true);
}

您可以通过方法mifareTag.connect()选择标签，在从android文档使用android方法进行身份验证后，您可以进行读写。https://developer.android.com/reference/android/nfc/tech/MifareClassic您在文档中找到错误“ B2”的含义是什么？