GCMParameterSpec

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.

See Also

• Cipher

Public Constructor Summary

	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.

Public Method Summary

byte[]	getIV() Returns the Initialization Vector (IV).
int	getTLen() Returns the authentication tag length.

Inherited Method Summary

From class java.lang.Object

Object	clone() Creates and returns a copy of this Object.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of Class that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object.

Public Constructors

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.

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.

Public Methods

public byte[] getIV ()

Returns the Initialization Vector (IV).

Returns

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

public int getTLen ()

Returns the authentication tag length.

Returns

• the authentication tag length (in bits)