NullCipher

AI-generated Key Takeaways

• The NullCipher class in Java cryptography provides an "identity cipher" that does not transform plaintext, resulting in ciphertext identical to the plaintext.

• It acts as a pass-through, with initialization methods having no effect and a block size of 1 byte.

• All encryption and decryption operations performed by NullCipher effectively return the original input data without any modifications.

• It inherits various constants and methods from the javax.crypto.Cipher class for compatibility but overrides them to maintain its identity transformation behavior.

• Developers might utilize NullCipher in scenarios where encryption is not desired but a Cipher object is required by an API or framework, or for testing and debugging purposes.

public class NullCipher extends Cipher

The NullCipher class is a class that provides an "identity cipher" -- one that does not transform the plain text. As a consequence, the ciphertext is identical to the plaintext. All initialization methods do nothing, while the blocksize is set to 1 byte.

Inherited Constant Summary

From class javax.crypto.Cipher

int	DECRYPT_MODE	Constant used to initialize cipher to decryption mode.
int	ENCRYPT_MODE	Constant used to initialize cipher to encryption mode.
int	PRIVATE_KEY	Constant used to indicate the to-be-unwrapped key is a "private key".
int	PUBLIC_KEY	Constant used to indicate the to-be-unwrapped key is a "public key".
int	SECRET_KEY	Constant used to indicate the to-be-unwrapped key is a "secret key".
int	UNWRAP_MODE	Constant used to initialize cipher to key-unwrapping mode.
int	WRAP_MODE	Constant used to initialize cipher to key-wrapping mode.

Public Constructor Summary

NullCipher() Creates a NullCipher object.

Inherited Method Summary

From class javax.crypto.Cipher

final int	doFinal(byte[] input, int inputOffset, int inputLen, byte[] output) Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation.
final int	doFinal(byte[] output, int outputOffset) Finishes a multiple-part encryption or decryption operation, depending on how this cipher was initialized.
final byte[]	doFinal() Finishes a multiple-part encryption or decryption operation, depending on how this cipher was initialized.
final byte[]	doFinal(byte[] input) Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation.
final int	doFinal(byte[] input, int inputOffset, int inputLen, byte[] output, int outputOffset) Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation.
final int	doFinal(ByteBuffer input, ByteBuffer output) Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation.
final byte[]	doFinal(byte[] input, int inputOffset, int inputLen) Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation.
final String	getAlgorithm() Returns the algorithm name of this Cipher object.
final int	getBlockSize() Returns the block size (in bytes).
final ExemptionMechanism	getExemptionMechanism() Returns the exemption mechanism object used with this cipher.
final byte[]	getIV() Returns the initialization vector (IV) in a new buffer.
final static Cipher	getInstance(String transformation) Returns a Cipher object that implements the specified transformation.
final static Cipher	getInstance(String transformation, String provider) Returns a Cipher object that implements the specified transformation.
final static Cipher	getInstance(String transformation, Provider provider) Returns a Cipher object that implements the specified transformation.
final static int	getMaxAllowedKeyLength(String transformation) Returns the maximum key length for the specified transformation according to the installed JCE jurisdiction policy files.
final static AlgorithmParameterSpec	getMaxAllowedParameterSpec(String transformation) Returns an AlgorithmParameterSpec object which contains the maximum cipher parameter value according to the jurisdiction policy file.
final int	getOutputSize(int inputLen) Returns the length in bytes that an output buffer would need to be in order to hold the result of the next update or doFinal operation, given the input length inputLen (in bytes).
final AlgorithmParameters	getParameters() Returns the parameters used with this cipher.
final Provider	getProvider() Returns the provider of this Cipher object.
final void	init(int opmode, Key key, AlgorithmParameters params) Initializes this cipher with a key and a set of algorithm parameters.
final void	init(int opmode, Certificate certificate, SecureRandom random) Initializes this cipher with the public key from the given certificate and a source of randomness.
final void	init(int opmode, Key key, SecureRandom random) Initializes this cipher with a key and a source of randomness.
final void	init(int opmode, Key key, AlgorithmParameterSpec params) Initializes this cipher with a key and a set of algorithm parameters.
final void	init(int opmode, Key key) Initializes this cipher with a key.
final void	init(int opmode, Key key, AlgorithmParameterSpec params, SecureRandom random) Initializes this cipher with a key, a set of algorithm parameters, and a source of randomness.
final void	init(int opmode, Certificate certificate) Initializes this cipher with the public key from the given certificate.
final void	init(int opmode, Key key, AlgorithmParameters params, SecureRandom random) Initializes this cipher with a key, a set of algorithm parameters, and a source of randomness.
final Key	unwrap(byte[] wrappedKey, String wrappedKeyAlgorithm, int wrappedKeyType) Unwrap a previously wrapped key.
final byte[]	update(byte[] input) Continues a multiple-part encryption or decryption operation (depending on how this cipher was initialized), processing another data part.
final int	update(byte[] input, int inputOffset, int inputLen, byte[] output) Continues a multiple-part encryption or decryption operation (depending on how this cipher was initialized), processing another data part.
final byte[]	update(byte[] input, int inputOffset, int inputLen) Continues a multiple-part encryption or decryption operation (depending on how this cipher was initialized), processing another data part.
final int	update(ByteBuffer input, ByteBuffer output) Continues a multiple-part encryption or decryption operation (depending on how this cipher was initialized), processing another data part.
final int	update(byte[] input, int inputOffset, int inputLen, byte[] output, int outputOffset) Continues a multiple-part encryption or decryption operation (depending on how this cipher was initialized), processing another data part.
final void	updateAAD(byte[] src, int offset, int len) Continues a multi-part update of the Additional Authentication Data (AAD), using a subset of the provided buffer.
final void	updateAAD(ByteBuffer src) Continues a multi-part update of the Additional Authentication Data (AAD).
final void	updateAAD(byte[] src) Continues a multi-part update of the Additional Authentication Data (AAD).
final byte[]	wrap(Key key) Wrap a key.

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 NullCipher ()

Creates a NullCipher object.