Class GCMParameterSpec

java.lang.Object

javax.crypto.spec.GCMParameterSpec

All Implemented Interfaces:

AlgorithmParameterSpec

public class GCMParameterSpec
extends Object
implements AlgorithmParameterSpec

Specifies the set of parameters required by a Cipher using the Galois/Counter Mode (GCM) mode.

Simple block cipher modes (such as CBC) generally require only an initialization vector (such as IvParameterSpec), but GCM needs these parameters:

• IV: Initialization Vector (IV)
• tLen: length (in bits) of authentication tag T

In addition to the parameters described here, other GCM inputs/output (Additional Authenticated Data (AAD), Keys, block ciphers, plain/ciphertext and authentication tags) are handled in the Cipher class.

Please see RFC 5116 for more information on the Authenticated Encryption with Associated Data (AEAD) algorithm, and NIST Special Publication 800-38D, "NIST Recommendation for Block Cipher Modes of Operation: Galois/Counter Mode (GCM) and GMAC."

The GCM specification states that tLen may only have the values {128, 120, 112, 104, 96}, or {64, 32} for certain applications. Other values can be specified for this class, but not all CSP implementations will support them.

Since:

1.7

External Specifications

• RFC 5116: An Interface and Algorithms for Authenticated Encryption
• Recommendation for Block Cipher Modes of Operation: Galois/Counter Mode (GCM) and GMAC

See Also:

• Cipher

Constructor Summary

Constructors

Constructor	Description
GCMParameterSpec(int tLen, byte[] src)	Constructs a GCMParameterSpec using the specified authentication tag bit-length and IV buffer.
GCMParameterSpec(int tLen, byte[] src, int offset, int len)	Constructs a GCMParameterSpec object using the specified authentication tag bit-length and a subset of the specified buffer as the IV.

Method Summary

Modifier and Type	Method	Description
byte[]	getIV()	Returns the Initialization Vector (IV).
int	getTLen()	Returns the authentication tag length.

Methods declared in class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Modifier and Type	Method	Description
protected Object	clone()	Answers a new instance of the same class as the receiver, whose slots have been filled in with the values in the slots of the receiver.
boolean	equals(Object o)	Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison.
protected void	finalize()	Deprecated, for removal: This API element is subject to removal in a future version. May cause performance issues, deadlocks and hangs.
final Class<? extends Object>	getClass()	Answers the unique instance of java.lang.Class which represents the class of the receiver.
int	hashCode()	Answers an integer hash code for the receiver.
final void	notify()	Causes one thread which is waiting on the receiver to be made ready to run.
final void	notifyAll()	Causes all threads which are waiting on the receiver to be made ready to run.
String	toString()	Answers a string containing a concise, human-readable description of the receiver.
final void	wait()	Causes the thread which sent this message to be made not ready to run pending some change in the receiver (as indicated by notify or notifyAll).
final void	wait(long time)	Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.
final void	wait(long time, int frac)	Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.

Constructor Details

GCMParameterSpec

public GCMParameterSpec(int tLen,
 byte[] src)

Constructs a GCMParameterSpec using the specified authentication tag bit-length and IV buffer.

Parameters:

tLen - the authentication tag length (in bits)

src - the IV source buffer. The contents of the buffer are copied to protect against subsequent modification.

Throws:

IllegalArgumentException - if tLen is negative, or src is null.

GCMParameterSpec

public GCMParameterSpec(int tLen,
 byte[] src,
 int offset,
 int len)

Constructs a GCMParameterSpec object using the specified authentication tag bit-length and a subset of the specified buffer as the IV.

Parameters:

tLen - the authentication tag length (in bits)

src - the IV source buffer. The contents of the buffer are copied to protect against subsequent modification.

offset - the offset in src where the IV starts

len - the number of IV bytes

Throws:

IllegalArgumentException - if tLen is negative, src is null, len or offset is negative, or the sum of offset and len is greater than the length of the src byte array.

Method Details

getTLen

public int getTLen()

Returns the authentication tag length.

Returns:

the authentication tag length (in bits)

getIV

public byte[] getIV()

Returns the Initialization Vector (IV).

Returns:

the IV. Creates a new array each time this method is called.