Class CommandAPDU

All Implemented Interfaces:
Serializable
public final class CommandAPDU
extends Object
implements Serializable

A command APDU following the structure defined in ISO/IEC 7816-4. It consists of a four byte header and a conditional body of variable length. This class does not attempt to verify that the APDU encodes a semantically valid command.

Note that when the expected length of the response APDU is specified in the constructors, the actual length (Ne) must be specified, not its encoded form (Le). Similarly, getNe() returns the actual value Ne. In other words, a value of 0 means "no data in the response APDU" rather than "maximum length."

This class supports both the short and extended forms of length encoding for Ne and Nc. However, note that not all terminals and Smart Cards are capable of accepting APDUs that use the extended form.

For the header bytes CLA, INS, P1, and P2 the Java type int is used to represent the 8 bit unsigned values. In the constructors, only the 8 lowest bits of the int value specified by the application are significant. The accessor methods always return the byte as an unsigned value between 0 and 255.

Instances of this class are immutable. Where data is passed in or out via byte arrays, defensive cloning is performed.

Since:
1.6
See Also:
ResponseAPDU, CardChannel.transmit, Serialized Form

Constructors

Constructor Description
CommandAPDU​(byte[] apdu)

Constructs a CommandAPDU from a byte array containing the complete APDU contents (header and body).
CommandAPDU​(byte[] apdu, int apduOffset, int apduLength)

Constructs a CommandAPDU from a byte array containing the complete APDU contents (header and body).
CommandAPDU​(int cla, int ins, int p1, int p2)

Constructs a CommandAPDU from the four header bytes.
CommandAPDU​(int cla, int ins, int p1, int p2, byte[] data)

Constructs a CommandAPDU from the four header bytes and command data.
CommandAPDU​(int cla, int ins, int p1, int p2, byte[] data, int ne)

Constructs a CommandAPDU from the four header bytes, command data, and expected response data length.
CommandAPDU​(int cla, int ins, int p1, int p2, byte[] data, int dataOffset, int dataLength)

Constructs a CommandAPDU from the four header bytes and command data.
CommandAPDU​(int cla, int ins, int p1, int p2, byte[] data, int dataOffset, int dataLength, int ne)

Constructs a CommandAPDU from the four header bytes, command data, and expected response data length.
CommandAPDU​(int cla, int ins, int p1, int p2, int ne)

Constructs a CommandAPDU from the four header bytes and the expected response data length.
CommandAPDU​(ByteBuffer apdu)

Creates a CommandAPDU from the ByteBuffer containing the complete APDU contents (header and body).

Methods

Modifier and Type Method Description
boolean equals​(Object obj)

Compares the specified object with this command APDU for equality.
byte[] getBytes()

Returns a copy of the bytes in this APDU.
int getCLA()

Returns the value of the class byte CLA.
byte[] getData()

Returns a copy of the data bytes in the command body.
int getINS()

Returns the value of the instruction byte INS.
int getNc()

Returns the number of data bytes in the command body (Nc) or 0 if this APDU has no body.
int getNe()

Returns the maximum number of expected data bytes in a response APDU (Ne).
int getP1()

Returns the value of the parameter byte P1.
int getP2()

Returns the value of the parameter byte P2.
int hashCode()

Returns the hash code value for this command APDU.
String toString()

Returns a string representation of this command APDU.

Methods declared in class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructors

CommandAPDU

public CommandAPDU(byte[] apdu)

Constructs a CommandAPDU from a byte array containing the complete APDU contents (header and body).

Note that the apdu bytes are copied to protect against subsequent modification.

Parameters:
apdu - the complete command APDU
Throws:
NullPointerException - if apdu is null
IllegalArgumentException - if apdu does not contain a valid command APDU

CommandAPDU

public CommandAPDU(byte[] apdu,
                   int apduOffset,
                   int apduLength)

Constructs a CommandAPDU from a byte array containing the complete APDU contents (header and body). The APDU starts at the index apduOffset in the byte array and is apduLength bytes long.

Note that the apdu bytes are copied to protect against subsequent modification.

Parameters:
apdu - the complete command APDU
apduOffset - the offset in the byte array at which the apdu data begins
apduLength - the length of the APDU
Throws:
NullPointerException - if apdu is null
IllegalArgumentException - if apduOffset or apduLength are negative or if apduOffset + apduLength are greater than apdu.length, or if the specified bytes are not a valid APDU

CommandAPDU

public CommandAPDU(ByteBuffer apdu)

Creates a CommandAPDU from the ByteBuffer containing the complete APDU contents (header and body). The buffer's position must be set to the start of the APDU, its limit to the end of the APDU. Upon return, the buffer's position is equal to its limit; its limit remains unchanged.

Note that the data in the ByteBuffer is copied to protect against subsequent modification.

Parameters:
apdu - the ByteBuffer containing the complete APDU
Throws:
NullPointerException - if apdu is null
IllegalArgumentException - if apdu does not contain a valid command APDU

CommandAPDU

public CommandAPDU(int cla,
                   int ins,
                   int p1,
                   int p2)

Constructs a CommandAPDU from the four header bytes. This is case 1 in ISO 7816, no command body.

Parameters:
cla - the class byte CLA
ins - the instruction byte INS
p1 - the parameter byte P1
p2 - the parameter byte P2

CommandAPDU

public CommandAPDU(int cla,
                   int ins,
                   int p1,
                   int p2,
                   int ne)

Constructs a CommandAPDU from the four header bytes and the expected response data length. This is case 2 in ISO 7816, empty command data field with Ne specified. If Ne is 0, the APDU is encoded as ISO 7816 case 1.

Parameters:
cla - the class byte CLA
ins - the instruction byte INS
p1 - the parameter byte P1
p2 - the parameter byte P2
ne - the maximum number of expected data bytes in a response APDU
Throws:
IllegalArgumentException - if ne is negative or greater than 65536

CommandAPDU

public CommandAPDU(int cla,
                   int ins,
                   int p1,
                   int p2,
                   byte[] data)

Constructs a CommandAPDU from the four header bytes and command data. This is case 3 in ISO 7816, command data present and Ne absent. The value Nc is taken as data.length. If data is null or its length is 0, the APDU is encoded as ISO 7816 case 1.

Note that the data bytes are copied to protect against subsequent modification.

Parameters:
cla - the class byte CLA
ins - the instruction byte INS
p1 - the parameter byte P1
p2 - the parameter byte P2
data - the byte array containing the data bytes of the command body
Throws:
IllegalArgumentException - if data.length is greater than 65535

CommandAPDU

public CommandAPDU(int cla,
                   int ins,
                   int p1,
                   int p2,
                   byte[] data,
                   int dataOffset,
                   int dataLength)

Constructs a CommandAPDU from the four header bytes and command data. This is case 3 in ISO 7816, command data present and Ne absent. The value Nc is taken as dataLength. If dataLength is 0, the APDU is encoded as ISO 7816 case 1.

Note that the data bytes are copied to protect against subsequent modification.

Parameters:
cla - the class byte CLA
ins - the instruction byte INS
p1 - the parameter byte P1
p2 - the parameter byte P2
data - the byte array containing the data bytes of the command body
dataOffset - the offset in the byte array at which the data bytes of the command body begin
dataLength - the number of the data bytes in the command body
Throws:
NullPointerException - if data is null and dataLength is not 0
IllegalArgumentException - if dataOffset or dataLength are negative or if dataOffset + dataLength are greater than data.length or if dataLength is greater than 65535

CommandAPDU

public CommandAPDU(int cla,
                   int ins,
                   int p1,
                   int p2,
                   byte[] data,
                   int ne)

Constructs a CommandAPDU from the four header bytes, command data, and expected response data length. This is case 4 in ISO 7816, command data and Ne present. The value Nc is taken as data.length if data is non-null and as 0 otherwise. If Ne or Nc are zero, the APDU is encoded as case 1, 2, or 3 per ISO 7816.

Note that the data bytes are copied to protect against subsequent modification.

Parameters:
cla - the class byte CLA
ins - the instruction byte INS
p1 - the parameter byte P1
p2 - the parameter byte P2
data - the byte array containing the data bytes of the command body
ne - the maximum number of expected data bytes in a response APDU
Throws:
IllegalArgumentException - if data.length is greater than 65535 or if ne is negative or greater than 65536

CommandAPDU

public CommandAPDU(int cla,
                   int ins,
                   int p1,
                   int p2,
                   byte[] data,
                   int dataOffset,
                   int dataLength,
                   int ne)

Constructs a CommandAPDU from the four header bytes, command data, and expected response data length. This is case 4 in ISO 7816, command data and Le present. The value Nc is taken as dataLength. If Ne or Nc are zero, the APDU is encoded as case 1, 2, or 3 per ISO 7816.

Note that the data bytes are copied to protect against subsequent modification.

Parameters:
cla - the class byte CLA
ins - the instruction byte INS
p1 - the parameter byte P1
p2 - the parameter byte P2
data - the byte array containing the data bytes of the command body
dataOffset - the offset in the byte array at which the data bytes of the command body begin
dataLength - the number of the data bytes in the command body
ne - the maximum number of expected data bytes in a response APDU
Throws:
NullPointerException - if data is null and dataLength is not 0
IllegalArgumentException - if dataOffset or dataLength are negative or if dataOffset + dataLength are greater than data.length, or if ne is negative or greater than 65536, or if dataLength is greater than 65535

Methods

getCLA

public int getCLA()

Returns the value of the class byte CLA.

Returns:
the value of the class byte CLA.

getINS

public int getINS()

Returns the value of the instruction byte INS.

Returns:
the value of the instruction byte INS.

getP1

public int getP1()

Returns the value of the parameter byte P1.

Returns:
the value of the parameter byte P1.

getP2

public int getP2()

Returns the value of the parameter byte P2.

Returns:
the value of the parameter byte P2.

getNc

public int getNc()

Returns the number of data bytes in the command body (Nc) or 0 if this APDU has no body. This call is equivalent to getData().length.

Returns:
the number of data bytes in the command body or 0 if this APDU has no body.

getData

public byte[] getData()

Returns a copy of the data bytes in the command body. If this APDU as no body, this method returns a byte array with length zero.

Returns:
a copy of the data bytes in the command body or the empty byte array if this APDU has no body.

getNe

public int getNe()

Returns the maximum number of expected data bytes in a response APDU (Ne).

Returns:
the maximum number of expected data bytes in a response APDU.

getBytes

public byte[] getBytes()

Returns a copy of the bytes in this APDU.

Returns:
a copy of the bytes in this APDU.

toString

public String toString()

Returns a string representation of this command APDU.

Overrides:
toString in class Object
Returns:
a String representation of this command APDU.

equals

public boolean equals(Object obj)

Compares the specified object with this command APDU for equality. Returns true if the given object is also a CommandAPDU and its bytes are identical to the bytes in this CommandAPDU.

Overrides:
equals in class Object
Parameters:
obj - the object to be compared for equality with this command APDU
Returns:
true if the specified object is equal to this command APDU
See Also:
Object.hashCode(), HashMap

hashCode

public int hashCode()

Returns the hash code value for this command APDU.

Overrides:
hashCode in class Object
Returns:
the hash code value for this command APDU.
See Also:
Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)

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https://docs.oracle.com/en/java/javase/11/docs/api/java.smartcardio/javax/smartcardio/CommandAPDU.html