blocks|key|279077|text|发送到标记的PWD_AUTH命令没有多大意义。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|279078|PWD_AUTH命令的思想是发送您的密码(一个4字节值)，如果您使用正确的密码进行身份验证，则标记将使用其密码应答，并使用其密码确认(PACK)值(一个2字节值)。然后，您可以根据预期的密码确认来验证PACK值，以“验证”标记。|279079|所以正确的命令是：|279080|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.)
}|code-block|syntax|javascript|279081|您需要什么才能启用密码保护(在NTAG212上)：|279082|将PWD+(第39页)设置为您想要的密码(默认值是0xFFFFFFFF)。
byte[]+response+=nfc.transceive(新的byte[]+{(字节)+0xA2，//写(字节)+39，//页面地址传递，pass1，pass2，pass3+})；|ordered-list-item|offset|length|style|CODE|279083|将PACK+(第40页，字节0-1)设置为您想要的密码确认(默认值是0x0000)。
byte[]+response+=nfc.transceive(新的byte[]+{(字节)+0xA2，//+byte[](字节)+40，//页地址包，pack1，//字节0-1是包值(字节)+0，(字节)0+//其他字节为RFU，必须写入0+})；|279084|将AUTHLIM+(第38页，字节0，位2-0)设置为失败密码验证尝试的最大次数(将此值设置为0将允许无限次数的PWD_AUTH尝试)。|279085|将PROT+(第38页，字节0，位7)设置为您想要的值(0+=+PWD_AUTH+(只用于写访问)，1=+PWD_AUTH是读写访问所必需的)。
byte[]+response+=nfc.transceive(新的byte[]+{(字节)+0x30，//+read+(字节)+38+//页地址})；if+((响应=+null)+&+(response.length+>=+16))+{+//+read总是返回4页布尔prot+=+false；//+false+=+PWD_AUTH表示只写，true+=+PWD_AUTH表示读和写int+authlim+=+0；//+byte[]+{(字节)+0xA2，//写(字节)+38，//页地址(字节)((响应&+0x078)+x+(prot+?+0x080+:+0x000)+)+(response1+&0x007)，response1，response2，response3+//保存字节1-3的旧值，您也可以简单地将它们设置为0，因为它们当前是RFU，并且必须始终写为0(response1、response2、response3也将包含0，因为它们包含read值)+})；}|279086|将AUTH0+(第37页，字节3)设置为需要密码身份验证的第一页。
byte[]+response+=nfc.transceive(新的byte[]+{(字节)+0x30，//+read+(字节)+37+//页地址})；if+((响应!=+null)+&+(response.length+>=+16))+{+//+read总是返回4页布尔prot+=+false；//+false+=+PWD_AUTH表示只写，true+=+PWD_AUTH表示读和写int+auth0+=+0；//+NTAG212+response+=nfc.transceive(新的byte[]+{(字节)+0xA2，//写(字节)+37，//页地址响应，//保持字节0+response1的旧值，//保持字节1+response2的旧值，//保持字节2(字节)的旧值(auth0+&+0x0ff)+})；}|279087|279088|279089|如果使用MifareUltralight标记技术，而不是直接使用transceive方法，还可以使用readPages和writePage方法：|279090|读取命令
byte[]+response+=nfc.transceive(新的byte[]+{(字节)+0x30，//+READ+(字节)+(pageAddress+&+0x0ff)+//页面地址})；
等于
byte[]反应=+nfc.readPages(pageAddress)；|unordered-list-item|279091|写命令
byte[]数据={(字节).(字节).}；byte[]+response+=nfc.transceive(新的byte[]+{(字节)+0xA2，//写(字节)+(pageAddress+&+0x0ff)，//页地址数据，data1，data2，data3+})；
等于
nfc.writePage(pageAddress，data)；|279092|279093|279094|entityMap^0|0|0|0|0|0|P|A|0|Y|6|0|0|0|0|0|0|4|G|W|A|1E|9|1O|9|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|1E|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1F|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|1G|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|1H|8|@]|9|@]|A|$I|J]]|$1|K|3|L|5|6|7|1I|8|@]|9|@]|A|$]]|$1|M|3|N|5|O|7|1J|8|@$P|1K|Q|1L|R|S]]|9|@]|A|$]]|$1|T|3|U|5|O|7|1M|8|@$P|1N|Q|1O|R|S]]|9|@]|A|$]]|$1|V|3|W|5|O|7|1P|8|@]|9|@]|A|$]]|$1|X|3|Y|5|O|7|1Q|8|@]|9|@]|A|$]]|$1|Z|3|10|5|O|7|1R|8|@]|9|@]|A|$]]|$1|11|3|-4|5|6|7|1S|8|@]|9|@]|A|$]]|$1|12|3|-4|5|6|7|1T|8|@]|9|@]|A|$]]|$1|13|3|14|5|6|7|1U|8|@$P|1V|Q|1W|R|S]|$P|1X|Q|1Y|R|S]|$P|1Z|Q|20|R|S]|$P|21|Q|22|R|S]]|9|@]|A|$]]|$1|15|3|16|5|17|7|23|8|@]|9|@]|A|$]]|$1|18|3|19|5|17|7|24|8|@]|9|@]|A|$]]|$1|1A|3|-4|5|6|7|25|8|@]|9|@]|A|$]]|$1|1B|3|-4|5|6|7|26|8|@]|9|@]|A|$]]|$1|1C|3|-4|5|6|7|27|8|@]|9|@]|A|$]]]|1D|$]]

The PWD_AUTH command that you send to the tag does not make much sense.

The idea of the PWD_AUTH command is that you send your password (a 4-byte value) and that the tag responds with its password acknowledge (PACK) value (a 2-byte value) if you authenticated with the correct password. You can then verify the PACK value against the expected password acknowledge to "authenticate" the tag.

So the correct command would be:

<pre><code>byte[] response = nfc.transceive(new byte[] {
 (byte) 0x1B, // PWD_AUTH
 pass[0], pass[1], pass[2], pass[3]
});
if ((response != null) &amp;&amp; (response.length &gt;= 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.)
}
</code></pre>

What you need in order to enable password protection (on NTAG212):

<ol>
<li>Set PWD (page 39) to your desired password (default value is <code>0xFFFFFFFF</code>).

<pre><code>byte[] response = nfc.transceive(new byte[] {
 (byte) 0xA2, // WRITE
 (byte) 39, // page address
 pass[0], pass[1], pass[2], pass[3]
});
</code></pre></li>
<li>Set PACK (page 40, bytes 0-1) to your desired password acknowledge (default value is <code>0x0000</code>).

<pre><code>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
});
</code></pre></li>
<li>Set AUTHLIM (page 38, byte 0, bits 2-0) to the maximum number of failed password verification attempts (setting this value to 0 will permit an unlimited number of PWD_AUTH attempts).</li>
<li>Set PROT (page 38, byte 0, bit 7) to your desired value (0 = PWD_AUTH in needed only for write access, 1 = PWD_AUTH is necessary for read and write access).

<pre><code>byte[] response = nfc.transceive(new byte[] {
 (byte) 0x30, // READ
 (byte) 38 // page address
});
if ((response != null) &amp;&amp; (response.length &gt;= 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] &amp; 0x078) | (prot ? 0x080 : 0x000) | (authlim &amp; 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)
 });
}
</code></pre></li>
<li>Set AUTH0 (page 37, byte 3) to the first page that should require password authentication.

<pre><code>byte[] response = nfc.transceive(new byte[] {
 (byte) 0x30, // READ
 (byte) 37 // page address
});
if ((response != null) &amp;&amp; (response.length &gt;= 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 &amp; 0x0ff)
 });
}
</code></pre></li>
</ol>

If you use <code>MifareUltralight</code> tag technology, instead of using the <code>transceive</code> method directly, you could also use the <code>readPages</code> and <code>writePage</code> methods:

<ul>
<li>The READ command

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

is equvalent to

<pre><code>byte[] response = nfc.readPages(pageAddress);
</code></pre></li>
<li>The WRITE command

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

is equvalent to

<pre><code>nfc.writePage(pageAddress, data);
</code></pre></li>
</ul>

blocks|key|3002606|text|当在TagLostException操作期间发送错误的密码时，一个将获得PWD_AUTH。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3002607|确保在PWD_AUTH操作中发送的4字节密码与使用常规WRITE操作设置标记的PWD字段的内容相匹配。|3002608|entityMap^0|2|G|10|8|0|3|8|R|5|13|3|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]|$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|H|3|-4|5|6|7|V|8|@]|D|@]|E|$]]]|I|$]]

One gets the <code>TagLostException</code> when sending a wrong password during the <code>PWD_AUTH</code> operation.
Make sure the 4-byte password sent in the <code>PWD_AUTH</code> operation matches what you used to set the tag's <code>PWD</code> field with a regular <code>WRITE</code> operation.

I am new to NFC Android and I have been stuck for days trying to get the Page 4 to page 7 of NTAG212 Mifare Ultralight with Authentication, I already have the PWD and PACK to do the PWD_AUTH based on the NTAG212 Docs.

I do this approach...

<pre><code>//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
 }
}
</code></pre>

I always receive a <code>android.nfc.TagLostException: Tag was lost.</code> Error after sending the PWD_AUTH command to the NFC. Can someone tell me what I am doing wrong? Is my approach correct? Please help.

NOTE: I have read the docs of NTAG212 many times, searched google, stackoverflow and all possible resources.
 
 
TIA, 
Kenster

NTAG212 Mifare Ultralight with Authentication

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我是NFC的新手，几天来，我一直在试图将NTAG212 Mifare的第7页与身份验证连接起来，我已经拥有了PWD，并准备了基于NTAG212 Docs的PWD_AUTH。我这么做..。//assume password as array of bytes//assume pack as array of bytest...

问具有身份验证的NTAG212 Mifare超视距
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问具有身份验证的NTAG212 Mifare超视距EN