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

See Also:

Constructor Summary

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()`	Creates and returns a copy of this object.
`boolean`	`equals(Object obj)`	Indicates whether some other object is "equal to" this one.
`protected void`	`finalize()`	Deprecated, for removal: This API element is subject to removal in a future version. Finalization is deprecated and subject to removal in a future release.
`final Class<?>`	`getClass()`	Returns the runtime class of this `Object`.
`int`	`hashCode()`	Returns a hash code value for this object.
`final void`	`notify()`	Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()`	Wakes up all threads that are waiting on this object's monitor.
`String`	`toString()`	Returns a string representation of the object.
`final void`	`wait()`	Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
`final void`	`wait(long timeoutMillis)`	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait(long timeoutMillis, int nanos)`	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

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.

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