NTAG212具有认证的Mifare Ultralight

您发送给标签的PWD_AUTH命令没有多大意义。

PWD_AUTH命令的想法是，您发送密码（一个4字节的值），并且如果您使用正确的密码进行了身份验证，则标签将以其密码确认（PACK）值（一个2字节的值）进行响应。然后，您可以对照预期的密码确认来验证PACK值，以“认证”标签。

因此正确的命令将是：

    byte[] response = nfc.transceive(new byte[] {        (byte) 0x1B, // PWD_AUTH        pass[0], pass[1], pass[2], pass[3]    });    if ((response != null) && (response.length >= 2)) {       byte[] pack = Arrays.copyOf(response, 2);       // TODO: verify PACK to confirm that tag is authentic (not really,       // but that whole PWD_AUTH/PACK authentication mechanism was not       // really meant to bring much security, I hope; same with the       // NTAG signature btw.)    }

启用密码保护所需的内容（在NTAG212上）：

1. 将PWD（第39页）设置为所需的密码（默认值为

   0xFFFFFFFF

   ）。

        byte[] response = nfc.transceive(new byte[] {        (byte) 0xA2, // WRITE        (byte) 39,   // page address        pass[0], pass[1], pass[2], pass[3]    });

1. 将PACK（第40页，字节0-1）设置为所需的密码确认（默认值为

   0x0000

   ）。

        byte[] response = nfc.transceive(new byte[] {        (byte) 0xA2, // WRITE        (byte) 40,   // page address        pack[0], pack[1],   // bytes 0-1 are PACK value        (byte) 0, (byte) 0  // other bytes are RFU and must be written as 0    });

1. 将AUTHLIM（第38页，字节0，位2-0）设置为失败的密码验证尝试的最大次数（将此值设置为0将允许无限制的PWD_AUTH尝试次数）。

2. 将PROT（第38页，字节0，位7）设置为所需值（0 =仅对写访问才需要PWD_AUTH，1 =对读和写访问才需要PWD_AUTH）。

        byte[] response = nfc.transceive(new byte[] {        (byte) 0x30, // READ        (byte) 38    // page address    });    if ((response != null) && (response.length >= 16)) {  // read always returns 4 pages        boolean prot = false;  // false = PWD_AUTH for write only, true = PWD_AUTH for read and write        int authlim = 0; // value between 0 and 7        response = nfc.transceive(new byte[] { (byte) 0xA2, // WRITE (byte) 38,   // page address (byte) ((response[0] & 0x078) | (prot ? 0x080 : 0x000) | (authlim & 0x007)), response[1], response[2], response[3]  // keep old value for bytes 1-3, you could also simply set them to 0 as they are currently RFU and must always be written as 0 (response[1], response[2], response[3] will contain 0 too as they contain the read RFU value)        });    }

1. 将AUTH0（第37页，字节3）设置为需要密码认证的第一页。

        byte[] response = nfc.transceive(new byte[] {        (byte) 0x30, // READ        (byte) 37    // page address    });    if ((response != null) && (response.length >= 16)) {  // read always returns 4 pages        boolean prot = false;  // false = PWD_AUTH for write only, true = PWD_AUTH for read and write        int auth0 = 0; // first page to be protected, set to a value between 0 and 37 for NTAG212        response = nfc.transceive(new byte[] { (byte) 0xA2, // WRITE (byte) 37,   // page address response[0], // keep old value for byte 0 response[1], // keep old value for byte 1 response[2], // keep old value for byte 2 (byte) (auth0 & 0x0ff)        });    }

如果使用

MifareUltralight

transceive

readPages

writePage

• READ命令

        byte[] response = nfc.transceive(new byte[] {        (byte) 0x30,       // READ        (byte) (pageAddress & 0x0ff)  // page address    });

等价于

        byte[] response = nfc.readPages(pageAddress);

• WRITE命令

        byte[] data = { (byte)..., (byte)..., (byte)..., (byte)... };    byte[] response = nfc.transceive(new byte[] {        (byte) 0xA2,       // WRITE        (byte) (pageAddress & 0x0ff), // page address        data[0], data[1], data[2], data[3]    });

等价于

    nfc.writePage(pageAddress, data);