All Packages Class Hierarchy This Package Previous Next Index
Class javax.crypto.KeyAgreement
java.lang.Object
|
+----javax.crypto.KeyAgreement
- public class KeyAgreement
- extends Object
This class provides the functionality of a key agreement (or key
exchange) protocol. The keys involved in establishing a shared secret
are created by one of the key generators (KeyPairGenerator or
KeyGenerator), a KeyFactory, or as a result from an intermediate
phase of the key agreement protocol (see doPhase). For each of the
correspondents in the key exchange, doPhase needs to be called. For
example, if this key exchange is with one other party, doPhase needs
to be called once, with the lastPhase flag set to true. If this key
exchange is with two other parties, doPhase needs to be called twice,
the first time setting the lastPhase flag to false, and the second
time setting it to true. There may be any number of parties involved
in a key exchange.
- See Also:
- KeyGenerator, SecretKey
-
KeyAgreement(KeyAgreementSpi, Provider, String)
- Creates a KeyAgreement object.
-
doPhase(Key, boolean)
- Executes the next phase of this key agreement with the given key that
was received from one of the other parties involved in this key
agreement.
-
generateSecret()
- Generates the shared secret and returns it in a new buffer.
-
generateSecret(byte[], int)
- Generates the shared secret, and places it into the buffer
sharedSecret, beginning at offset.
-
generateSecret(String)
- Creates the shared secret and returns it as a SecretKey object of the
specified algorithm.
-
getAlgorithm()
- Returns the name of this KeyAgreement object.
-
getInstance(String)
- Generates a KeyAgreement object that implements the specified key
agreement algorithm.
-
getInstance(String, String)
- Generates a KeyAgreement object for the specified key agreement
algorithm from the specified provider.
-
getProvider()
- Returns the provider of this KeyAgreement object.
-
init(Key)
- Initialises this key agreement with the given key, which is required
to contain all the algorithm parameters required for this key
agreement.
-
init(Key, AlgorithmParameterSpec)
- Initialises this key agreement with the given key and set of algorithm
parameters.
-
init(Key, AlgorithmParameterSpec, SecureRandom)
- Initialises this key agreement with the given key, set of algorithm
parameters, and source of randomness.
-
init(Key, SecureRandom)
- Initialises this key agreement with the given key and source of
randomness.
KeyAgreement
protected KeyAgreement(KeyAgreementSpi keyAgreeSpi,
Provider provider,
String algorithm)
- Creates a KeyAgreement object.
- Parameters:
- keyAgreeSpi - the delegate
- provider - the provider
- algorithm - the algorithm
getAlgorithm
public final String getAlgorithm()
- Returns the name of this KeyAgreement object.
This is the same name that was specified in one of the getInstance
calls that created this KeyAgreement object.
- Returns:
- the algorithm name of this KeyAgreement object.
getInstance
public static final KeyAgreement getInstance(String algorithm) throws NoSuchAlgorithmException
- Generates a KeyAgreement object that implements the specified key
agreement algorithm. If the default provider package provides an
implementation of the requested key agreement algorithm, an
instance of KeyAgreement containing that implementation is
returned. If the algorithm is not available in the default
provider package, other provider packages are searched.
- Parameters:
- algorithm - - the standard name of the requested key
agreement algorithm. See Appendix A in the Java Cryptography
Extension API Specification & Reference for information about
standard algorithm names.
- Returns:
- the new KeyAgreement object
- Throws: NoSuchAlgorithmException
- - if the specified algorithm
is not available in the default provider package or any of the
other provider packages that were searched.
getInstance
public static final KeyAgreement getInstance(String algorithm,
String provider) throws NoSuchAlgorithmException, NoSuchProviderException
- Generates a KeyAgreement object for the specified key agreement
algorithm from the specified provider.
- Parameters:
- algorithm - - the standard name of the requested key
agreement algorithm. See Appendix A in the Java Cryptography
Extension API Specification & Reference for information about
standard algorithm names.
- provider - - the name of the provider
- Returns:
- the new KeyAgreement object
- Throws: NoSuchAlgorithmException
- - if the specified algorithm
is not available in the default provider package or any of the
other provider packages that were searched.
- Throws: NoSuchProviderException
- - if the specified provider has
not be configured
getProvider
public final Provider getProvider()
- Returns the provider of this KeyAgreement object.
- Returns:
- the provider of this KeyAgreement object
init
public final void init(Key key) throws InvalidKeyException
- Initialises this key agreement with the given key, which is required
to contain all the algorithm parameters required for this key
agreement.
If this key agreement requires any random bytes, it will get them
using the SecureRandom implementation of the highest-priority
installed provider as the source of randomness. (If none of the
installed providers supply an implementation of SecureRandom, a
system-provided source of randomness will be used.)
- Parameters:
- key - the party's private information. For example, in the case
of the Diffie-Hellman key agreement, this would be the party's own
Diffie-Hellman private key.
- Throws: InvalidKeyException
- if the given key is inappropriate for
this key agreement, e.g., is of the wrong type or has an incompatible
algorithm type.
init
public final void init(Key key,
SecureRandom random) throws InvalidKeyException
- Initialises this key agreement with the given key and source of
randomness. The given key is required to contain all the algorithm
parameters required for this key agreement.
If the key agreement algorithm requires random bytes, it gets them from
the given source of randomness, random. However, if the underlying
algorithm implementation does not require any random bytes, random is
ignored.
- Parameters:
- key - the party's private information. For example, in the case of
the Diffie-Hellman key agreement, this would be the party's own
Diffie-Hellman private key.
- random - the source of randomness
- Throws: InvalidKeyException
- if the given key is
inappropriate for this key agreement, e.g., is of the wrong type or
has an incompatible algorithm type.
init
public final void init(Key key,
AlgorithmParameterSpec params) throws InvalidKeyException, InvalidAlgorithmParameterException
- Initialises this key agreement with the given key and set of algorithm
parameters.
If this key agreement requires any random bytes, it will get them
using the SecureRandom implementation of the highest-priority
installed provider as the source of randomness. (If none of the
installed providers supply an implementation of SecureRandom, a
system-provided source of randomness will be used.)
- Parameters:
- key - the party's private information. For example, in the case of
the Diffie-Hellman key agreement, this would be the party's own
Diffie-Hellman private key.
- params - the key agreement parameters
- Throws: InvalidKeyException
- if the given key is
inappropriate for this key agreement, e.g., is of the wrong type or
has an incompatible algorithm type.
- Throws: InvalidAlgorithmParameterException
- if the given
parameters are inappropriate for this key agreement.
init
public final void init(Key key,
AlgorithmParameterSpec params,
SecureRandom random) throws InvalidKeyException, InvalidAlgorithmParameterException
- Initialises this key agreement with the given key, set of algorithm
parameters, and source of randomness.
- Parameters:
- key - the party's private information. For example, in the case of
the Diffie-Hellman key agreement, this would be the party's own
Diffie-Hellman private key.
- params - the key agreement parameters
- random - the source of randomness
- Throws: InvalidKeyException
- if the given key is inappropriate
for this key agreement, e.g., is of the wrong type or
has an incompatible algorithm type.
- Throws: InvalidAlgorithmParameterException
- if the given
parameters are inappropriate for this key agreement.
doPhase
public final Key doPhase(Key key,
boolean lastPhase) throws InvalidKeyException, IllegalStateException
- Executes the next phase of this key agreement with the given key that
was received from one of the other parties involved in this key
agreement.
- Parameters:
- key - the key for this phase. For example, in the case of
Diffie-Hellman between 2 parties, this would be the other party's
Diffie-Hellman public key.
- lastPhase - flag which indicates whether or not this is the last
phase of this key agreement.
- Returns:
- the (intermediate) key resulting from this phase, or null
if this phase does not yield a key
- Throws: InvalidKeyException
- if the given key is
inappropriate for this phase.
- Throws: IllegalStateException
- if this key agreement has not
been initialised.
generateSecret
public final byte[] generateSecret() throws IllegalStateException
- Generates the shared secret and returns it in a new buffer.
This method resets this KeyAgreement object, so that it can be reused
for further key agreements. Unless this key agreement is reinitialised
with one of the init methods, the same private information and
algorithm parameters will be used for subsequent key agreements.
- Returns:
- the new buffer with the shared secret
- Throws: IllegalStateException
- - if this key agreement has not
been completed yet
generateSecret
public final int generateSecret(byte sharedSecret[],
int offset) throws IllegalStateException, ShortBufferException
- Generates the shared secret, and places it into the buffer
sharedSecret, beginning at offset.
If the sharedSecret buffer is too small to hold the result, a
ShortBufferException is thrown. In this case, this call should be
repeated with a larger output buffer.
This method resets this KeyAgreement object, so that it can be reused
for further key agreements. Unless this key agreement is reinitialised
with one of the init methods, the same private information and
algorithm parameters will be used for subsequent key agreements.
- Parameters:
- sharedSecret - the buffer for the shared secret
- offset - the offset in sharedSecret where the shared secret
will be stored
- Returns:
- the number of bytes placed into sharedSecret
- Throws: IllegalStateException
- if this key agreement has not
been completed yet
- Throws: ShortBufferException
- if the given output buffer is too
small to hold the secret
generateSecret
public final SecretKey generateSecret(String algorithm) throws IllegalStateException, NoSuchAlgorithmException, InvalidKeyException
- Creates the shared secret and returns it as a SecretKey object of the
specified algorithm.
This method resets this KeyAgreement object, so that it can be reused
for further key agreements. Unless this key agreement is reinitialised
with one of the init methods, the same private information and
algorithm parameters will be used for subsequent key agreements.
- Parameters:
- algorithm - the requested secret-key algorithm
- Returns:
- the shared secret key
- Throws: IllegalStateException
- if this key agreement has not
been completed yet
- Throws: NoSuchAlgorithmException
- if the specified
secret-key algorithm is not available
- Throws: InvalidKeyException
- if the shared secret-key
material cannot be used to generate a secret key of the specified
algorithm (e.g., the key material is too short)
All Packages Class Hierarchy This Package Previous Next Index