[英]Write and read data to Mifare Classic 1k NFC tag
I am trying to read and write data on a Mifare Classic 1k NFC tag.我正在尝试在 Mifare Classic 1k NFC 标签上读取和写入数据。
I found the keys and the access conditions of the card thanks to this app :由于这个应用程序,我找到了卡的钥匙和访问条件:
Keys:钥匙:
Access Conditions:访问条件:
<uses-permission android:name="android.permission.NFC" />
is present in my manifest. <uses-permission android:name="android.permission.NFC" />
存在于我的清单中。
Here is my code:这是我的代码:
Tag tag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
if(tag != null) {
Log.i("hey", Arrays.toString(tag.getTechList()));
MifareClassic mfc = MifareClassic.get(tag) ;
try {
mfc.connect();
boolean authA = mfc.authenticateSectorWithKeyA(2, MifareClassic.KEY_NFC_FORUM) ;
boolean authB = mfc.authenticateSectorWithKeyB(2, MifareClassic.KEY_DEFAULT) ;
Log.i("hey", "authA : " + authA) ;
Log.i("hey", "authB : " + authB) ;
if (authB && authA) {
byte[] bWrite = new byte[16];
byte[] hello = "hello".getBytes(StandardCharsets.US_ASCII);
System.arraycopy(hello, 0, bWrite, 0, hello.length);
mfc.writeBlock(0, bWrite);
Log.i("hey", "write : " + Arrays.toString(bWrite));
byte[] bRead = mfc.readBlock(0);
String str = new String(bRead, StandardCharsets.US_ASCII);
Log.i("hey", "read bytes : " + Arrays.toString(bRead));
Log.i("hey", "read string : " + str);
Toast.makeText(this, "read : " + str, Toast.LENGTH_SHORT).show();
Log.i("hey", "expected : " + new String(bWrite, StandardCharsets.US_ASCII));
}
mfc.close();
} catch (IOException e) {
Toast.makeText(this, "Error", Toast.LENGTH_SHORT).show();
e.printStackTrace();
Log.i("hey", "Error") ;
}
}
When I try to write and read like that, what I read is not what I wrote.当我尝试这样写作和阅读时,我读到的不是我写的。
Here is the logcat:这是日志猫:
I/hey: [android.nfc.tech.NfcA, android.nfc.tech.MifareClassic, android.nfc.tech.NdefFormatable]
I/hey: authA : true
authB : true
I/hey: write : [104, 101, 108, 108, 111, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
I/hey: read byte : [-78, 0, 0, 0, 0, 0, -1, 7, -128, 105, -1, -1, -1, -1, -1, -1]
read string : �������������i������
I/hey: expected : hello����������������������
I tried with different charsets but it didn't change anything.我尝试了不同的字符集,但它没有改变任何东西。
I also tried to only read the Sector 0 by commenting the write part and changing authentication key A to MifareClassic.KEY_MIFARE_APPLICATION_DIRECTORY
and this time I get this Logcat:我还尝试通过评论写入部分并将身份验证密钥 A 更改为
MifareClassic.KEY_MIFARE_APPLICATION_DIRECTORY
来仅读取扇区 0,这次我得到了这个 Logcat:
I/hey: [android.nfc.tech.NfcA, android.nfc.tech.MifareClassic, android.nfc.tech.NdefFormatable]
I/hey: authA : true
authB : true
I/hey: read bytes : [-123, -121, 0, 16, 18, 8, 4, 0, 1, -64, 62, -70, 74, 124, 78, 29]
read string : �������>�J|N
Any idea about how can I fix it to write and display text properly?关于如何修复它以正确编写和显示文本的任何想法?
You first authenticate to sector 2:您首先对扇区 2 进行身份验证:
boolean authA = mfc.authenticateSectorWithKeyA(2, MifareClassic.KEY_NFC_FORUM);
boolean authB = mfc.authenticateSectorWithKeyB(2, MifareClassic.KEY_DEFAULT);
Then, you try to write and read block 0:然后,您尝试写入和读取块 0:
mfc.writeBlock(0, bWrite);
byte[] bRead = mfc.readBlock(0);
There are several problems with this:这有几个问题:
It does not make sense to authenticate using both key A and key B. Only the last authentication determines the authentication state of the tag.使用密钥 A 和密钥 B 进行身份验证是没有意义的。只有最后一次身份验证才能确定标签的身份验证状态。 Since all sectors seem to be writable using key B, you can safely use the second line (
mfc.authenticateSectorWithKeyB()
only).由于所有扇区似乎都可以使用密钥 B 写入,因此您可以安全地使用第二行(
mfc.authenticateSectorWithKeyB()
)。
You authenticate to sector 2, which consists of blocks 8, 9, 10, and 11. Writing and reading block 0 does not make sense in that authentication state.您对扇区 2 进行身份验证,该扇区由块 8、9、10 和 11 组成。在该身份验证状态下写入和读取块 0 没有意义。 Note that read/write operations typically use global block numbering.
请注意,读/写操作通常使用全局块编号。 Sectors are only used as logical units for authentication/access control purposes.
扇区仅用作用于身份验证/访问控制目的的逻辑单元。 You can easily calculate block numbers from sector numbering using
mfc.sectorToBlock()
and mfc.getBlockCountInSector()
.您可以使用
mfc.sectorToBlock()
和mfc.getBlockCountInSector()
从扇区编号轻松计算块编号。
Block 0 (in sector 0) is a special block, the manufacturer block.块 0(在扇区 0 中)是一个特殊块,即制造商块。 It typically contains the UID, SAK and manufacturer information burned into the tag during the production process.
它通常包含在生产过程中烧入标签的 UID、SAK 和制造商信息。 This block is read-only and cannot be changed.
此块是只读的,不能更改。 Consequently, writing to that block does not have any effect.
因此,写入该块没有任何效果。
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