/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package javax.crypto;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.Provider;
import java.security.ProviderException;
import java.security.SecureRandom;
import java.security.Security;
import java.security.spec.AlgorithmParameterSpec;
import java.util.ArrayList;
import org.apache.harmony.security.fortress.Engine;
/**
* 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.
*/
public class KeyAgreement {
// The service name.
private static final String SERVICE = "KeyAgreement";
// Used to access common engine functionality
private static final Engine ENGINE = new Engine(SERVICE);
// Store SecureRandom
private static final SecureRandom RANDOM = new SecureRandom();
// Store used provider
private Provider provider;
// Provider that was requested during creation.
private final Provider specifiedProvider;
// Store used spi implementation
private KeyAgreementSpi spiImpl;
// Store used algorithm name
private final String algorithm;
/**
* Lock held while the SPI is initializing.
*/
private final Object initLock = new Object();
/**
* Creates a new {@code KeyAgreement} instance.
*
* @param keyAgreeSpi
* the <b>SPI</b> delegate.
* @param provider
* the provider providing this KeyAgreement.
* @param algorithm
* the name of the key agreement algorithm.
*/
protected KeyAgreement(KeyAgreementSpi keyAgreeSpi, Provider provider,
String algorithm) {
this.spiImpl = keyAgreeSpi;
this.specifiedProvider = provider;
this.algorithm = algorithm;
}
/**
* Returns the name of the key agreement algorithm.
*
* @return the name of the key agreement algorithm.
*/
public final String getAlgorithm() {
return algorithm;
}
/**
* Returns the provider for this {@code KeyAgreement} instance.
*
* @return the provider for this {@code KeyAgreement} instance.
*/
public final Provider getProvider() {
getSpi();
return provider;
}
/**
* Creates a new {@code KeyAgreement} for the specified algorithm.
*
* @param algorithm
* the name of the key agreement algorithm to create.
* @return a key agreement for the specified algorithm.
* @throws NoSuchAlgorithmException
* if no installed provider can provide the requested algorithm.
* @throws NullPointerException
* if the specified algorithm is {@code null}.
*/
public static final KeyAgreement getInstance(String algorithm) throws NoSuchAlgorithmException {
return getKeyAgreement(algorithm, null);
}
/**
* Creates a new {@code KeyAgreement} for the specified algorithm from the
* specified provider.
*
* @param algorithm
* the name of the key agreement algorithm to create.
* @param provider
* the name of the provider that provides the requested
* algorithm.
* @return a key agreement for the specified algorithm from the specified
* provider.
* @throws NoSuchAlgorithmException
* if the specified provider cannot provide the requested
* algorithm.
* @throws NoSuchProviderException
* if the specified provider does not exist.
* @throws IllegalArgumentException
* if the specified provider name is {@code null} or empty.
*/
public static final KeyAgreement getInstance(String algorithm, String provider)
throws NoSuchAlgorithmException, NoSuchProviderException {
if (provider == null || provider.isEmpty()) {
throw new IllegalArgumentException("Provider is null or empty");
}
Provider impProvider = Security.getProvider(provider);
if (impProvider == null) {
throw new NoSuchProviderException(provider);
}
return getKeyAgreement(algorithm, impProvider);
}
/**
* Create a new {@code KeyAgreement} for the specified algorithm from the
* specified provider. The {@code provider} supplied does not have to be
* registered.
*
* @param algorithm
* the name of the key agreement algorithm to create.
* @param provider
* the provider that provides the requested algorithm.
* @return a key agreement for the specified algorithm from the specified
* provider.
* @throws NoSuchAlgorithmException
* if the specified provider cannot provide the requested
* algorithm.
* @throws IllegalArgumentException
* if the specified provider is {@code null}.
* @throws NullPointerException
* if the specified algorithm name is {@code null}.
*/
public static final KeyAgreement getInstance(String algorithm, Provider provider)
throws NoSuchAlgorithmException {
if (provider == null) {
throw new IllegalArgumentException("provider == null");
}
return getKeyAgreement(algorithm, provider);
}
private static KeyAgreement getKeyAgreement(String algorithm, Provider provider)
throws NoSuchAlgorithmException {
if (algorithm == null) {
throw new NullPointerException("algorithm == null");
}
if (tryAlgorithm(null, provider, algorithm) == null) {
if (provider == null) {
throw new NoSuchAlgorithmException("No provider found for " + algorithm);
} else {
throw new NoSuchAlgorithmException("Provider " + provider.getName()
+ " does not provide " + algorithm);
}
}
return new KeyAgreement(null, provider, algorithm);
}
private static Engine.SpiAndProvider tryAlgorithm(Key key, Provider provider, String algorithm) {
if (provider != null) {
Provider.Service service = provider.getService(SERVICE, algorithm);
if (service == null) {
return null;
}
return tryAlgorithmWithProvider(key, service);
}
ArrayList<Provider.Service> services = ENGINE.getServices(algorithm);
if (services == null) {
return null;
}
for (Provider.Service service : services) {
Engine.SpiAndProvider sap = tryAlgorithmWithProvider(key, service);
if (sap != null) {
return sap;
}
}
return null;
}
private static Engine.SpiAndProvider tryAlgorithmWithProvider(Key key, Provider.Service service) {
try {
if (key != null && !service.supportsParameter(key)) {
return null;
}
Engine.SpiAndProvider sap = ENGINE.getInstance(service, null);
if (sap.spi == null || sap.provider == null) {
return null;
}
if (!(sap.spi instanceof KeyAgreementSpi)) {
return null;
}
return sap;
} catch (NoSuchAlgorithmException ignored) {
}
return null;
}
/**
* Makes sure a KeyAgreementSpi that matches this type is selected.
*/
private KeyAgreementSpi getSpi(Key key) {
synchronized (initLock) {
if (spiImpl != null && key == null) {
return spiImpl;
}
final Engine.SpiAndProvider sap = tryAlgorithm(key, specifiedProvider, algorithm);
if (sap == null) {
throw new ProviderException("No provider for " + getAlgorithm());
}
spiImpl = (KeyAgreementSpi) sap.spi;
provider = sap.provider;
return spiImpl;
}
}
/**
* Convenience call when the Key is not available.
*/
private KeyAgreementSpi getSpi() {
return getSpi(null);
}
/**
* Initializes this {@code KeyAgreement} with the specified key.
*
* @param key the key to initialize this key agreement.
* @throws InvalidKeyException if the specified key cannot be used to
* initialize this key agreement.
*/
public final void init(Key key) throws InvalidKeyException {
getSpi(key).engineInit(key, RANDOM);//new SecureRandom());
}
/**
* Initializes this {@code KeyAgreement} with the specified key and the
* specified randomness source.
*
* @param key
* the key to initialize this key agreement.
* @param random
* the source for any randomness needed.
* @throws InvalidKeyException
* if the specified key cannot be used to initialize this key
* agreement.
*/
public final void init(Key key, SecureRandom random)
throws InvalidKeyException {
getSpi(key).engineInit(key, random);
}
/**
* Initializes this {@code KeyAgreement} with the specified key and the
* algorithm parameters.
*
* @param key
* the key to initialize this key agreement.
* @param params
* the parameters for this key agreement algorithm.
* @throws InvalidKeyException
* if the specified key cannot be used to initialize this key
* agreement.
* @throws InvalidAlgorithmParameterException
* if the specified parameters are invalid for this key
* agreement algorithm.
*/
public final void init(Key key, AlgorithmParameterSpec params)
throws InvalidKeyException, InvalidAlgorithmParameterException {
getSpi(key).engineInit(key, params, RANDOM);//new SecureRandom());
}
/**
* Initializes this {@code KeyAgreement} with the specified key, algorithm
* parameters and randomness source.
*
* @param key
* the key to initialize this key agreement.
* @param params
* the parameters for this key agreement algorithm.
* @param random
* the source for any randomness needed.
* @throws InvalidKeyException
* if the specified key cannot be used to initialize this key
* agreement.
* @throws InvalidAlgorithmParameterException
* if the specified parameters are invalid for this key
* agreement algorithm.
*/
public final void init(Key key, AlgorithmParameterSpec params,
SecureRandom random) throws InvalidKeyException,
InvalidAlgorithmParameterException {
getSpi(key).engineInit(key, params, random);
}
/**
* Does the next (or the last) phase of the key agreement, using the
* specified key.
*
* @param key
* the key received from the other party for this phase.
* @param lastPhase
* set to {@code true} if this is the last phase of this key
* agreement.
* @return the intermediate key from this phase or {@code 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,
* @throws IllegalStateException
* if this instance has not been initialized.
*/
public final Key doPhase(Key key, boolean lastPhase)
throws InvalidKeyException, IllegalStateException {
return getSpi().engineDoPhase(key, lastPhase);
}
/**
* Generates the shared secret.
*
* @return the generated shared secret.
* @throws IllegalStateException
* if this key agreement is not complete.
*/
public final byte[] generateSecret() throws IllegalStateException {
return getSpi().engineGenerateSecret();
}
/**
* Generates the shared secret and stores it into the buffer {@code
* sharedSecred} at {@code offset}.
*
* @param sharedSecret
* the buffer to store the shared secret.
* @param offset
* the offset in the buffer.
* @return the number of bytes stored in the buffer.
* @throws IllegalStateException
* if this key agreement is not complete.
* @throws ShortBufferException
* if the specified buffer is too small for the shared secret.
*/
public final int generateSecret(byte[] sharedSecret, int offset)
throws IllegalStateException, ShortBufferException {
return getSpi().engineGenerateSecret(sharedSecret, offset);
}
/**
* Generates the shared secret.
*
* @param algorithm
* the algorithm to for the {@code SecretKey}
* @return the shared secret as a {@code SecretKey} of the specified
* algorithm.
* @throws IllegalStateException
* if this key agreement is not complete.
* @throws NoSuchAlgorithmException
* if the specified algorithm for the secret key does not
* exists.
* @throws InvalidKeyException
* if a {@code SecretKey} with the specified algorithm cannot be
* created using the generated shared secret.
*/
public final SecretKey generateSecret(String algorithm)
throws IllegalStateException, NoSuchAlgorithmException,
InvalidKeyException {
return getSpi().engineGenerateSecret(algorithm);
}
}