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Android APIs
public final class

MifareClassic

extends Object
implements TagTechnology
java.lang.Object
   ↳ android.nfc.tech.MifareClassic

Class Overview

Provides access to MIFARE Classic properties and I/O operations on a Tag .

Acquire a MifareClassic object using get(Tag) .

MIFARE Classic is also known as MIFARE Standard.

MIFARE Classic tags are divided into sectors, and each sector is sub-divided into blocks. Block size is always 16 bytes ( BLOCK_SIZE . Sector size varies.

  • MIFARE Classic Mini are 320 bytes ( SIZE_MINI ), with 5 sectors each of 4 blocks.
  • MIFARE Classic 1k are 1024 bytes ( SIZE_1K ), with 16 sectors each of 4 blocks.
  • MIFARE Classic 2k are 2048 bytes ( SIZE_2K ), with 32 sectors each of 4 blocks.
  • MIFARE Classic 4k} are 4096 bytes ( SIZE_4K ). The first 32 sectors contain 4 blocks and the last 8 sectors contain 16 blocks.

MIFARE Classic tags require authentication on a per-sector basis before any other I/O operations on that sector can be performed. There are two keys per sector, and ACL bits determine what I/O operations are allowed on that sector after authenticating with a key. and .

Three well-known authentication keys are defined in this class: KEY_DEFAULT , KEY_MIFARE_APPLICATION_DIRECTORY , KEY_NFC_FORUM .

Summary

Constants
int BLOCK_SIZE Size of a MIFARE Classic block (in bytes)
int SIZE_1K Tag contains 16 sectors, each with 4 blocks.
int SIZE_2K Tag contains 32 sectors, each with 4 blocks.
int SIZE_4K Tag contains 40 sectors.
int SIZE_MINI Tag contains 5 sectors, each with 4 blocks.
int TYPE_CLASSIC A MIFARE Classic tag
int TYPE_PLUS A MIFARE Plus tag
int TYPE_PRO A MIFARE Pro tag
int TYPE_UNKNOWN A MIFARE Classic compatible card of unknown type
Fields
public static final byte[] KEY_DEFAULT The default factory key.
public static final byte[] KEY_MIFARE_APPLICATION_DIRECTORY The well-known key for tags formatted according to the MIFARE Application Directory (MAD) specification.
public static final byte[] KEY_NFC_FORUM The well-known key for tags formatted according to the NDEF on MIFARE Classic specification.
Public Methods
boolean authenticateSectorWithKeyA (int sectorIndex, byte[] key)
Authenticate a sector with key A.
boolean authenticateSectorWithKeyB (int sectorIndex, byte[] key)
Authenticate a sector with key B.
int blockToSector (int blockIndex)
Return the sector that contains a given block.
void close ()
Disable I/O operations to the tag from this TagTechnology object, and release resources.
void connect ()
Enable I/O operations to the tag from this TagTechnology object.
void decrement (int blockIndex, int value)
Decrement a value block, storing the result in the temporary block on the tag.
static MifareClassic get ( Tag tag)
Get an instance of MifareClassic for the given tag.
int getBlockCount ()
Return the total number of MIFARE Classic blocks.
int getBlockCountInSector (int sectorIndex)
Return the number of blocks in the given sector.
int getMaxTransceiveLength ()
Return the maximum number of bytes that can be sent with transceive(byte[]) .
int getSectorCount ()
Return the number of MIFARE Classic sectors.
int getSize ()
Return the size of the tag in bytes

One of SIZE_MINI , SIZE_1K , SIZE_2K , SIZE_4K .

Tag getTag ()
Get the Tag object backing this TagTechnology object.
int getTimeout ()
Get the current transceive(byte[]) timeout in milliseconds.
int getType ()
Return the type of this MIFARE Classic compatible tag.
void increment (int blockIndex, int value)
Increment a value block, storing the result in the temporary block on the tag.
boolean isConnected ()
Helper to indicate if I/O operations should be possible.
byte[] readBlock (int blockIndex)
Read 16-byte block.
void restore (int blockIndex)
Copy from a value block to the temporary block.
int sectorToBlock (int sectorIndex)
Return the first block of a given sector.
void setTimeout (int timeout)
Set the transceive(byte[]) timeout in milliseconds.
byte[] transceive (byte[] data)
Send raw NfcA data to a tag and receive the response.
void transfer (int blockIndex)
Copy from the temporary block to a value block.
void writeBlock (int blockIndex, byte[] data)
Write 16-byte block.
[Expand]
Inherited Methods
From class java.lang.Object
From interface android.nfc.tech.TagTechnology
From interface java.io.Closeable
From interface java.lang.AutoCloseable

Constants

public static final int BLOCK_SIZE

Added in API level 10

Size of a MIFARE Classic block (in bytes)

Constant Value: 16 (0x00000010)

public static final int SIZE_1K

Added in API level 10

Tag contains 16 sectors, each with 4 blocks.

Constant Value: 1024 (0x00000400)

public static final int SIZE_2K

Added in API level 10

Tag contains 32 sectors, each with 4 blocks.

Constant Value: 2048 (0x00000800)

public static final int SIZE_4K

Added in API level 10

Tag contains 40 sectors. The first 32 sectors contain 4 blocks and the last 8 sectors contain 16 blocks.

Constant Value: 4096 (0x00001000)

public static final int SIZE_MINI

Added in API level 10

Tag contains 5 sectors, each with 4 blocks.

Constant Value: 320 (0x00000140)

public static final int TYPE_CLASSIC

Added in API level 10

A MIFARE Classic tag

Constant Value: 0 (0x00000000)

public static final int TYPE_PLUS

Added in API level 10

A MIFARE Plus tag

Constant Value: 1 (0x00000001)

public static final int TYPE_PRO

Added in API level 10

A MIFARE Pro tag

Constant Value: 2 (0x00000002)

public static final int TYPE_UNKNOWN

Added in API level 10

A MIFARE Classic compatible card of unknown type

Constant Value: -1 (0xffffffff)

Fields

public static final byte[] KEY_DEFAULT

Added in API level 10

The default factory key.

public static final byte[] KEY_MIFARE_APPLICATION_DIRECTORY

Added in API level 10

The well-known key for tags formatted according to the MIFARE Application Directory (MAD) specification.

public static final byte[] KEY_NFC_FORUM

Added in API level 10

The well-known key for tags formatted according to the NDEF on MIFARE Classic specification.

Public Methods

public boolean authenticateSectorWithKeyA (int sectorIndex, byte[] key)

Authenticate a sector with key A.

Successful authentication of a sector with key A enables other I/O operations on that sector. The set of operations granted by key A key depends on the ACL bits set in that sector. For more information see the MIFARE Classic specification on .

A failed authentication attempt causes an implicit reconnection to the tag, so authentication to other sectors will be lost.

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 IOException if close() is called from another thread.

Requires the NFC permission.

Parameters
sectorIndex index of sector to authenticate, starting from 0
key 6-byte authentication key
Returns
  • true on success, false on authentication failure
Throws
TagLostException if the tag leaves the field
IOException if there is an I/O failure, or the operation is canceled
See Also

public boolean authenticateSectorWithKeyB (int sectorIndex, byte[] key)

Authenticate a sector with key B.

Successful authentication of a sector with key B enables other I/O operations on that sector. The set of operations granted by key B depends on the ACL bits set in that sector. For more information see the MIFARE Classic specification on .

A failed authentication attempt causes an implicit reconnection to the tag, so authentication to other sectors will be lost.

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 IOException if close() is called from another thread.

Requires the NFC permission.

Parameters
sectorIndex index of sector to authenticate, starting from 0
key 6-byte authentication key
Returns
  • true on success, false on authentication failure
Throws
TagLostException if the tag leaves the field
IOException if there is an I/O failure, or the operation is canceled
See Also

public int blockToSector (int blockIndex)

Return the sector that contains a given block.

Does not cause any RF activity and does not block.

Parameters
blockIndex index of block to lookup, starting from 0
Returns
  • sector index that contains the block

public void close ()

Disable I/O operations to the tag from this TagTechnology object, and release resources.

Also causes all blocked I/O operations on other thread to be canceled and return with IOException .

Requires the NFC permission.

Throws
IOException

public void connect ()

Enable I/O operations to the tag from this TagTechnology object.

May cause RF activity and may block. Must not be called from the main application thread. A blocked call will be canceled with IOException by calling close() from another thread.

Only one TagTechnology object can be connected to a Tag at a time.

Applications must call close() when I/O operations are complete.

Requires the NFC permission.

Throws
IOException

public void decrement (int blockIndex, int value)

Decrement a value block, storing the result in the temporary block on the tag.

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 IOException if close() is called from another thread.

Requires the NFC permission.

Parameters
blockIndex index of block to decrement, starting from 0
value non-negative to decrement by
Throws
TagLostException if the tag leaves the field
IOException if there is an I/O failure, or the operation is canceled

public static MifareClassic get ( Tag tag)

Get an instance of MifareClassic for the given tag.

Does not cause any RF activity and does not block.

Returns null if MifareClassic was not enumerated in getTechList() . This indicates the tag is not MIFARE Classic compatible, or this Android device does not support MIFARE Classic.

Parameters
tag an MIFARE Classic compatible tag
Returns
  • MIFARE Classic object

public int getBlockCount ()

Return the total number of MIFARE Classic blocks.

Does not cause any RF activity and does not block.

Returns
  • total number of blocks

public int getBlockCountInSector (int sectorIndex)

Return the number of blocks in the given sector.

Does not cause any RF activity and does not block.

Parameters
sectorIndex index of sector, starting from 0
Returns
  • number of blocks in the sector

public int getMaxTransceiveLength ()

Return the maximum number of bytes that can be sent with transceive(byte[]) .

Returns

public int getSectorCount ()

Return the number of MIFARE Classic sectors.

Does not cause any RF activity and does not block.

Returns
  • number of sectors

public int getSize ()

Return the size of the tag in bytes

One of SIZE_MINI , SIZE_1K , SIZE_2K , SIZE_4K . These constants are equal to their respective size in bytes.

Does not cause any RF activity and does not block.

Returns
  • size in bytes

public Tag getTag ()

Get the Tag object backing this TagTechnology object.

Returns

public int getTimeout ()

Get the current transceive(byte[]) timeout in milliseconds.

Requires the NFC permission.

Returns
  • timeout value in milliseconds

public int getType ()

Return the type of this MIFARE Classic compatible tag.

One of TYPE_UNKNOWN , TYPE_CLASSIC , TYPE_PLUS or TYPE_PRO .

Does not cause any RF activity and does not block.

Returns
  • type

public void increment (int blockIndex, int value)

Increment a value block, storing the result in the temporary block on the tag.

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 IOException if close() is called from another thread.

Requires the NFC permission.

Parameters
blockIndex index of block to increment, starting from 0
value non-negative to increment by
Throws
TagLostException if the tag leaves the field
IOException if there is an I/O failure, or the operation is canceled

public boolean isConnected ()

Helper to indicate if I/O operations should be possible.

Returns true if connect() has completed, and close() has not been called, and the Tag is not known to be out of range.

Does not cause RF activity, and does not block.

Returns
  • true if I/O operations should be possible

public byte[] readBlock (int blockIndex)

Read 16-byte block.

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 IOException if close() is called from another thread.

Requires the NFC permission.

Parameters
blockIndex index of block to read, starting from 0
Returns
  • 16 byte block
Throws
TagLostException if the tag leaves the field
IOException if there is an I/O failure, or the operation is canceled

public void restore (int blockIndex)

Copy from a value block to the temporary block.

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 IOException if close() is called from another thread.

Requires the NFC permission.

Parameters
blockIndex index of block to copy from
Throws
TagLostException if the tag leaves the field
IOException if there is an I/O failure, or the operation is canceled

public int sectorToBlock (int sectorIndex)

Return the first block of a given sector.

Does not cause any RF activity and does not block.

Parameters
sectorIndex index of sector to lookup, starting from 0
Returns
  • block index of first block in sector

public void setTimeout (int timeout)

Set the transceive(byte[]) timeout in milliseconds.

The timeout only applies to transceive(byte[]) on this object, and is reset to a default value when close() is called.

Setting a longer timeout may be useful when performing transactions that require a long processing time on the tag such as key generation.

Requires the NFC permission.

Parameters
timeout timeout value in milliseconds

public byte[] transceive (byte[] data)

Send raw NfcA data to a tag and receive the response.

This is equivalent to connecting to this tag via NfcA and calling transceive(byte[]) . Note that all MIFARE Classic tags are based on NfcA technology.

Use getMaxTransceiveLength() to retrieve the maximum number of bytes that can be sent with transceive(byte[]) .

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 IOException if close() is called from another thread.

Requires the NFC permission.

Throws
IOException
See Also

public void transfer (int blockIndex)

Copy from the temporary block to a value block.

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 IOException if close() is called from another thread.

Requires the NFC permission.

Parameters
blockIndex index of block to copy to
Throws
TagLostException if the tag leaves the field
IOException if there is an I/O failure, or the operation is canceled

public void writeBlock (int blockIndex, byte[] data)

Write 16-byte block.

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 IOException if close() is called from another thread.

Requires the NFC permission.

Parameters
blockIndex index of block to write, starting from 0
data 16 bytes of data to write
Throws
TagLostException if the tag leaves the field
IOException if there is an I/O failure, or the operation is canceled