javax.crypto

Class KeyAgreement

java.lang.Object

javax.crypto.KeyAgreement

public class KeyAgreement
extends Object

This class provides the functionality for a key exchange protocol. This enables two or more parties to agree on a secret key for symmetric cryptography.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	KeyAgreement(KeyAgreementSpi keyAgreeSpi, Provider provider, String algorithm) Creates a new KeyAgreement instance.

Method Summary

Modifier and Type	Method and Description
Key	doPhase(Key key, boolean lastPhase) Does the next (or the last) phase of the key agreement, using the specified key.
byte[]	generateSecret() Generates the shared secret.
int	generateSecret(byte[] sharedSecret, int offset) Generates the shared secret and stores it into the buffer sharedSecred at offset.
SecretKey	generateSecret(String algorithm) Generates the shared secret.
String	getAlgorithm() Returns the name of the key agreement algorithm.
KeyAgreementSpi	getCurrentSpi() Returns the KeyAgreementSpi backing this KeyAgreement or null if no KeyAgreementSpi is backing this KeyAgreement.
static KeyAgreement	getInstance(String algorithm) Creates a new KeyAgreement for the specified algorithm.
static KeyAgreement	getInstance(String algorithm, Provider provider) Create a new KeyAgreement for the specified algorithm from the specified provider.
static KeyAgreement	getInstance(String algorithm, String provider) Creates a new KeyAgreement for the specified algorithm from the specified provider.
Provider	getProvider() Returns the provider for this KeyAgreement instance.
void	init(Key key) Initializes this KeyAgreement with the specified key.
void	init(Key key, AlgorithmParameterSpec params) Initializes this KeyAgreement with the specified key and the algorithm parameters.
void	init(Key key, AlgorithmParameterSpec params, SecureRandom random) Initializes this KeyAgreement with the specified key, algorithm parameters and randomness source.
void	init(Key key, SecureRandom random) Initializes this KeyAgreement with the specified key and the specified randomness source.

Methods inherited from class java.lang.Object

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

Constructor Detail

KeyAgreement

protected KeyAgreement(KeyAgreementSpi keyAgreeSpi,
                       Provider provider,
                       String algorithm)

Creates a new KeyAgreement instance.

Parameters:

keyAgreeSpi - the SPI delegate.

provider - the provider providing this KeyAgreement.

algorithm - the name of the key agreement algorithm.

Method Detail

getAlgorithm

public final String getAlgorithm()

Returns the name of the key agreement algorithm.

Returns:

the name of the key agreement algorithm.

getProvider

public final Provider getProvider()

Returns the provider for this KeyAgreement instance.

Returns:

the provider for this KeyAgreement instance.

getInstance

public static final KeyAgreement getInstance(String algorithm)
                                      throws NoSuchAlgorithmException

Creates a new KeyAgreement for the specified algorithm.

Parameters:

algorithm - the name of the key agreement algorithm to create.

Returns:

a key agreement for the specified algorithm.

Throws:

NoSuchAlgorithmException - if no installed provider can provide the requested algorithm.

NullPointerException - if the specified algorithm is null.

getInstance

public static final KeyAgreement getInstance(String algorithm,
                                             String provider)
                                      throws NoSuchAlgorithmException,
                                             NoSuchProviderException

Creates a new KeyAgreement for the specified algorithm from the specified provider.

Parameters:

algorithm - the name of the key agreement algorithm to create.

provider - the name of the provider that provides the requested algorithm.

Returns:

a key agreement for the specified algorithm from the specified provider.

Throws:

NoSuchAlgorithmException - if the specified provider cannot provide the requested algorithm.

NoSuchProviderException - if the specified provider does not exist.

IllegalArgumentException - if the specified provider name is null or empty.

getInstance

public static final KeyAgreement getInstance(String algorithm,
                                             Provider provider)
                                      throws NoSuchAlgorithmException

Create a new KeyAgreement for the specified algorithm from the specified provider. The provider supplied does not have to be registered.

Parameters:

algorithm - the name of the key agreement algorithm to create.

provider - the provider that provides the requested algorithm.

Returns:

a key agreement for the specified algorithm from the specified provider.

Throws:

NoSuchAlgorithmException - if the specified provider cannot provide the requested algorithm.

IllegalArgumentException - if the specified provider is null.

NullPointerException - if the specified algorithm name is null.

getCurrentSpi

public KeyAgreementSpi getCurrentSpi()

Returns the KeyAgreementSpi backing this KeyAgreement or null if no KeyAgreementSpi is backing this KeyAgreement.

init

public final void init(Key key)
                throws InvalidKeyException

Initializes this KeyAgreement with the specified key.

Parameters:

key - the key to initialize this key agreement.

Throws:

InvalidKeyException - if the specified key cannot be used to initialize this key agreement.

init

public final void init(Key key,
                       SecureRandom random)
                throws InvalidKeyException

Initializes this KeyAgreement with the specified key and the specified randomness source.

Parameters:

key - the key to initialize this key agreement.

random - the source for any randomness needed.

Throws:

InvalidKeyException - if the specified key cannot be used to initialize this key agreement.

init

public final void init(Key key,
                       AlgorithmParameterSpec params)
                throws InvalidKeyException,
                       InvalidAlgorithmParameterException

Initializes this KeyAgreement with the specified key and the algorithm parameters.

Parameters:

key - the key to initialize this key agreement.

params - the parameters for this key agreement algorithm.

Throws:

InvalidKeyException - if the specified key cannot be used to initialize this key agreement.

InvalidAlgorithmParameterException - if the specified parameters are invalid for this key agreement algorithm.

init

public final void init(Key key,
                       AlgorithmParameterSpec params,
                       SecureRandom random)
                throws InvalidKeyException,
                       InvalidAlgorithmParameterException

Initializes this KeyAgreement with the specified key, algorithm parameters and randomness source.

Parameters:

key - the key to initialize this key agreement.

params - the parameters for this key agreement algorithm.

random - the source for any randomness needed.

Throws:

InvalidKeyException - if the specified key cannot be used to initialize this key agreement.

InvalidAlgorithmParameterException - if the specified parameters are invalid for this key agreement algorithm.

doPhase

public final Key doPhase(Key key,
                         boolean lastPhase)
                  throws InvalidKeyException,
                         IllegalStateException

Does the next (or the last) phase of the key agreement, using the specified key.

Parameters:

key - the key received from the other party for this phase.

lastPhase - set to true if this is the last phase of this key agreement.

Returns:

the intermediate key from this phase or null if there is no intermediate key for this phase.

Throws:

InvalidKeyException - if the specified key cannot be used in this key agreement or this phase,

IllegalStateException - if this instance has not been initialized.

generateSecret

public final byte[] generateSecret()
                            throws IllegalStateException

Generates the shared secret.

Returns:

the generated shared secret.

Throws:

IllegalStateException - if this key agreement is not complete.

generateSecret

public final int generateSecret(byte[] sharedSecret,
                                int offset)
                         throws IllegalStateException,
                                ShortBufferException

Generates the shared secret and stores it into the buffer sharedSecred at offset.

Parameters:

sharedSecret - the buffer to store the shared secret.

offset - the offset in the buffer.

Returns:

the number of bytes stored in the buffer.

Throws:

IllegalStateException - if this key agreement is not complete.

ShortBufferException - if the specified buffer is too small for the shared secret.

generateSecret

public final SecretKey generateSecret(String algorithm)
                               throws IllegalStateException,
                                      NoSuchAlgorithmException,
                                      InvalidKeyException

Generates the shared secret.

Parameters:

algorithm - the algorithm to for the SecretKey

Returns:

the shared secret as a SecretKey of the specified algorithm.

Throws:

IllegalStateException - if this key agreement is not complete.

NoSuchAlgorithmException - if the specified algorithm for the secret key does not exists.

InvalidKeyException - if a SecretKey with the specified algorithm cannot be created using the generated shared secret.