我是NFC Android的新手,我已经被困了几天试图获得 NTAG212 Mifare Ultralight认证的第7页,我已经有了PWD和PACK来做< strong> PWD_AUTH 基于 NTAG212 文档。
我这样做......
//assume password as array of bytes
//assume pack as array of bytes
try{
nfc.connect();
byte[] cmd1 = nfc.transceive(new byte[]{ (byte) 0x30, (byte) 0x00 }); //read the page 0 to make the NFC active
nfc.transceive(new byte[]{
(byte) 0x1B, //command for PWD_AUTH
pass[0],
pass[1],
pass[2],
pass[3]
});
byte[] cmd4 = nfc.transceive(new byte[]{ (byte) 0x30, (byte) 0x04 }); //read the page 4
}catch(TagLostException e){
e.printStackTrace();
}catch(IOException e){
e.printStachTrace();
}finally{
try{
nfc.close();
}catch(Exception e){
//display failed to close
}
}
将PWD_AUTH命令发送到NFC后,我总是收到android.nfc.TagLostException: Tag was lost.
错误。有人能告诉我我做错了什么吗?我的方法是否正确?请帮忙。
注意:我已多次阅读NTAG212的文档,搜索了google,stackoverflow和所有可能的资源。
TIA,
Kenster
答案 0 :(得分:7)
您发送给标记的PWD_AUTH命令没有多大意义。
PWD_AUTH命令的想法是,如果使用正确的密码进行身份验证,则发送密码(4字节值)并且标签以其密码确认(PACK)值(2字节值)进行响应。然后,您可以根据预期密码确认来验证PACK值,以“验证”标签。
所以正确的命令是:
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):
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]
});
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
});
将AUTHLIM(第38页,字节0,位2-0)设置为密码验证尝试失败的最大次数(将此值设置为0将允许无限次数的PWD_AUTH尝试)。
< / LI>将PROT(第38页,字节0,位7)设置为所需的值(0 =仅在写访问时需要PWD_AUTH,1 =读和写访问需要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)
});
}
将AUTH0(第37页,第3页)设置为需要密码验证的第一页。
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)
});
}
如果您使用MifareUltralight
代码技术,而不是直接使用transceive
方法,您还可以使用readPages
和writePage
方法:
READ命令
byte[] response = nfc.transceive(new byte[] {
(byte) 0x30, // READ
(byte) (pageAddress & 0x0ff) // page address
});
等于
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]
});
等于
nfc.writePage(pageAddress, data);
答案 1 :(得分:0)
在 PWD_AUTH
操作期间发送错误密码时会得到 PWD_AUTH
。
确保在 PWD
操作中发送的 4 字节密码与您使用常规 WRITE
操作设置标签的 keytool -list -v -alias androiddebugkey -keystore %USERPROFILE%\.android\debug.keystore
字段时使用的密码相匹配。