GNU Classpath (0.95) | |

Prev Class | Next Class | Frames | No Frames |

Summary: Nested | Field | Method | Constr | Detail: Nested | Field | Method | Constr |

`java.lang.Object`

`javax.crypto.KeyAgreement`

`public class `**KeyAgreement**

`extends Object`

Key agreement is a method in which two or more parties may agree on a
secret key for symmetric cryptography or message authentication
without transmitting any secrets in the clear. Key agreement
algorithms typically use a public/private *key pair*, and the
public key (along with some additional information) is sent across
untrusted networks.

The most common form of key agreement used today is the
*Diffie-Hellman key exchange algorithm*, described in PKCS #3 -
Diffie Hellman Key Agreement Standard.

**Since:**- 1.4

**See Also:**`KeyGenerator`

,`SecretKey`

## Constructor Summary

`KeyAgreement(KeyAgreementSpi kaSpi, Provider provider, String algorithm)`

## Method Summary

`Key`

`byte[]`

`generateSecret()`

- Generate the shared secret in a new byte array.

`int`

`generateSecret(byte[] sharedSecret, int offset)`

- Generate the shared secret and store it into the supplied array.

`SecretKey`

`generateSecret(String algorithm)`

- Generate the shared secret and return it as an appropriate
`SecretKey`

.

`String`

`getAlgorithm()`

- Return the name of this key-agreement algorithm.

`static KeyAgreement`

`getInstance(String algorithm)`

- Get an implementation of an algorithm from the first provider that implements it.

`static KeyAgreement`

`getInstance(String algorithm, String provider)`

- Return an implementation of an algorithm from a named provider.

`static KeyAgreement`

`getInstance(String algorithm, Provider provider)`

- Return an implementation of an algorithm from a specific provider.

`Provider`

`getProvider()`

- Return the provider of the underlying implementation.

`void`

`void`

`init(Key key, SecureRandom random)`

- Initialize this key agreement with a key and a source of randomness.

`void`

`init(Key key, AlgorithmParameterSpec params)`

- Initialize this key agreement with a key and parameters.

`void`

`init(Key key, AlgorithmParameterSpec params, SecureRandom random)`

- Initialize this key agreement with a key, parameters, and source of randomness.

### Methods inherited from class java.lang.Object

`clone`

,`equals`

,`extends Object> getClass`

,`finalize`

,`hashCode`

,`notify`

,`notifyAll`

,`toString`

,`wait`

,`wait`

,`wait`

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

Do a phase in the key agreement. The number of times this method is called depends upon the algorithm and the number of parties involved, but must be called at least once with the`lastPhase`

flag set to`true`

.

Parameters:`key`

- The key for this phase.`lastPhase`

- Should be`true`

if this will be the last phase before generating the shared secret.

Returns:- The intermediate result, or
`null`

if there is no intermediate result.

Throws:`IllegalStateException`

- If this instance has not been initialized.`InvalidKeyException`

- If the key is inappropriate for this algorithm.

public final byte[] generateSecret() throws IllegalStateException

Generate the shared secret in a new byte array.

Returns:- The shared secret.

Throws:`IllegalStateException`

- If this instnace has not been initialized, or if not enough calls to`doPhase`

have been made.

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

Generate the shared secret and store it into the supplied array.

Parameters:`sharedSecret`

- The array in which to store the secret.`offset`

- The index in`sharedSecret`

to start storing data.

Returns:- The length of the shared secret, in bytes.

Throws:`IllegalStateException`

- If this instnace has not been initialized, or if not enough calls to`doPhase`

have been made.`ShortBufferException`

- If the supplied array is not large enough to store the result.

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

Generate the shared secret and return it as an appropriate`SecretKey`

.

Parameters:`algorithm`

- The secret key's algorithm.

Returns:- The shared secret as a secret key.

Throws:`IllegalStateException`

- If this instnace has not been initialized, or if not enough calls to`doPhase`

have been made.`InvalidKeyException`

- If the shared secret cannot be used to make a`SecretKey`

.`NoSuchAlgorithmException`

- If the specified algorithm does not exist.

public final String getAlgorithm()

Return the name of this key-agreement algorithm.

Returns:- The algorithm name.

public static final KeyAgreement getInstance(String algorithm) throws NoSuchAlgorithmException

Get an implementation of an algorithm from the first provider that implements it.

Parameters:`algorithm`

- The name of the algorithm to get.

Returns:- The proper KeyAgreement instacne, if found.

Throws:`NoSuchAlgorithmException`

- If the specified algorithm is not implemented by any installed provider.`IllegalArgumentException`

- if`algorithm`

is`null`

or is an empty string.

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

Return an implementation of an algorithm from a named provider.

Parameters:`algorithm`

- The name of the algorithm to create.`provider`

- The name of the provider from which to get the implementation.

Returns:- The proper KeyAgreement instance, if found.

Throws:`NoSuchAlgorithmException`

- If the named provider does not implement the algorithm.`NoSuchProviderException`

- If the named provider does not exist.`IllegalArgumentException`

- if either`algorithm`

or`provider`

is`null`

, or if`algorithm`

is an empty string.

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

Return an implementation of an algorithm from a specific provider.

Parameters:`algorithm`

- The name of the algorithm to get.`provider`

- The provider from which to get the implementation.

Returns:- The proper KeyAgreement instance, if found.

Throws:`NoSuchAlgorithmException`

- If this provider does not implement the algorithm.`IllegalArgumentException`

- if either`algorithm`

or`provider`

is`null`

, or if`algorithm`

is an empty string.

public final Provider getProvider()

Return the provider of the underlying implementation.

Returns:- The provider.

public final void init(Key key) throws InvalidKeyException

Initialize this key agreement with a key. This method will use the highest-priority`SecureRandom`

as its source of randomness.

Parameters:`key`

- The key, usually the user's private key.

Throws:`InvalidKeyException`

- If the supplied key is not appropriate.

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

Initialize this key agreement with a key and a source of randomness.

Parameters:`key`

- The key, usually the user's private key.`random`

- The source of randomness.

Throws:`InvalidKeyException`

- If the supplied key is not appropriate.

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

Initialize this key agreement with a key and parameters. This method will use the highest-priority`SecureRandom`

as its source of randomness.

Parameters:`key`

- The key, usually the user's private key.`params`

- The algorithm parameters.

Throws:`InvalidAlgorithmParameterException`

- If the supplied parameters are not appropriate.`InvalidKeyException`

- If the supplied key is not appropriate.

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

Initialize this key agreement with a key, parameters, and source of randomness.

Parameters:`key`

- The key, usually the user's private key.`params`

- The algorithm parameters.`random`

- The source of randomness.

Throws:`InvalidAlgorithmParameterException`

- If the supplied parameters are not appropriate.`InvalidKeyException`

- If the supplied key is not appropriate.

KeyAgreement.java -- Engine for key agreement methods.
Copyright (C) 2004 Free Software Foundation, Inc.
This file is part of GNU Classpath.
GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
GNU Classpath is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with GNU Classpath; see the file COPYING. If not, write to the
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA.
Linking this library statically or dynamically with other modules is
making a combined work based on this library. Thus, the terms and
conditions of the GNU General Public License cover the whole
combination.
As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under
terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
module. An independent module is a module which is not derived from
or based on this library. If you modify this library, you may extend
this exception to your version of the library, but you are not
obligated to do so. If you do not wish to do so, delete this
exception statement from your version.

GNU Classpath (0.95) |