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package javax.crypto;
import java.util.*;
import java.security.*;
import java.security.Provider.Service;
import java.security.spec.*;
import sun.security.jca.*;
import sun.security.jca.GetInstance.Instance;
/**
* This class provides the functionality of a secret (symmetric) key generator.
*
* <p>Key generators are constructed using one of the <code>getInstance</code>
* class methods of this class.
*
* <p>KeyGenerator objects are reusable, i.e., after a key has been
* generated, the same KeyGenerator object can be re-used to generate further
* keys.
*
* <p>There are two ways to generate a key: in an algorithm-independent
* manner, and in an algorithm-specific manner.
* The only difference between the two is the initialization of the object:
*
* <ul>
* <li><b>Algorithm-Independent Initialization</b>
* <p>All key generators share the concepts of a <i>keysize</i> and a
* <i>source of randomness</i>.
* There is an
* {@link #init(int, java.security.SecureRandom) init}
* method in this KeyGenerator class that takes these two universally
* shared types of arguments. There is also one that takes just a
* <code>keysize</code> argument, and uses the SecureRandom implementation
* of the highest-priority installed provider as the source of randomness
* (or a system-provided source of randomness if none of the installed
* providers supply a SecureRandom implementation), and one that takes just a
* source of randomness.
*
* <p>Since no other parameters are specified when you call the above
* algorithm-independent <code>init</code> methods, it is up to the
* provider what to do about the algorithm-specific parameters (if any) to be
* associated with each of the keys.
* <p>
*
* <li><b>Algorithm-Specific Initialization</b>
* <p>For situations where a set of algorithm-specific parameters already
* exists, there are two
* {@link #init(java.security.spec.AlgorithmParameterSpec) init}
* methods that have an <code>AlgorithmParameterSpec</code>
* argument. One also has a <code>SecureRandom</code> argument, while the
* other uses the SecureRandom implementation
* of the highest-priority installed provider as the source of randomness
* (or a system-provided source of randomness if none of the installed
* providers supply a SecureRandom implementation).
* </ul>
*
* <p>In case the client does not explicitly initialize the KeyGenerator
* (via a call to an <code>init</code> method), each provider must
* supply (and document) a default initialization.
*
* @author Jan Luehe
*
* @see SecretKey
* @since 1.4
*/
public class KeyGenerator {
// see java.security.KeyPairGenerator for failover notes
private final static int I_NONE = 1;
private final static int I_RANDOM = 2;
private final static int I_PARAMS = 3;
private final static int I_SIZE = 4;
// The provider
private Provider provider;
// The provider implementation (delegate)
private volatile KeyGeneratorSpi spi;
// The algorithm
private final String algorithm;
private final Object lock = new Object();
private Iterator serviceIterator;
private int initType;
private int initKeySize;
private AlgorithmParameterSpec initParams;
private SecureRandom initRandom;
/**
* Creates a KeyGenerator object.
*
* @param keyGenSpi the delegate
* @param provider the provider
* @param algorithm the algorithm
*/
protected KeyGenerator(KeyGeneratorSpi keyGenSpi, Provider provider,
String algorithm) {
this.spi = keyGenSpi;
this.provider = provider;
this.algorithm = algorithm;
}
private KeyGenerator(String algorithm) throws NoSuchAlgorithmException {
this.algorithm = algorithm;
List list = GetInstance.getServices("KeyGenerator", algorithm);
serviceIterator = list.iterator();
initType = I_NONE;
// fetch and instantiate initial spi
if (nextSpi(null, false) == null) {
throw new NoSuchAlgorithmException
(algorithm + " KeyGenerator not available");
}
}
/**
* Returns the algorithm name of this <code>KeyGenerator</code> object.
*
* <p>This is the same name that was specified in one of the
* <code>getInstance</code> calls that created this
* <code>KeyGenerator</code> object.
*
* @return the algorithm name of this <code>KeyGenerator</code> object.
*/
public final String getAlgorithm() {
return this.algorithm;
}
/**
* Returns a <code>KeyGenerator</code> object that generates secret keys
* for the specified algorithm.
*
* <p> This method traverses the list of registered security Providers,
* starting with the most preferred Provider.
* A new KeyGenerator object encapsulating the
* KeyGeneratorSpi implementation from the first
* Provider that supports the specified algorithm is returned.
*
* <p> Note that the list of registered providers may be retrieved via
* the {@link Security#getProviders() Security.getProviders()} method.
*
* @param algorithm the standard name of the requested key algorithm.
* See Appendix A in the
* <a href=
* "{@docRoot}/../technotes/guides/security/crypto/CryptoSpec.html#AppA">
* Java Cryptography Architecture Reference Guide</a>
* for information about standard algorithm names.
*
* @return the new <code>KeyGenerator</code> object.
*
* @exception NullPointerException if the specified algorithm is null.
*
* @exception NoSuchAlgorithmException if no Provider supports a
* KeyGeneratorSpi implementation for the
* specified algorithm.
*
* @see java.security.Provider
*/
public static final KeyGenerator getInstance(String algorithm)
throws NoSuchAlgorithmException {
return new KeyGenerator(algorithm);
}
/**
* Returns a <code>KeyGenerator</code> object that generates secret keys
* for the specified algorithm.
*
* <p> A new KeyGenerator object encapsulating the
* KeyGeneratorSpi implementation from the specified provider
* is returned. The specified provider must be registered
* in the security provider list.
*
* <p> Note that the list of registered providers may be retrieved via
* the {@link Security#getProviders() Security.getProviders()} method.
*
* @param algorithm the standard name of the requested key algorithm.
* See Appendix A in the
* <a href=
* "{@docRoot}/../technotes/guides/security/crypto/CryptoSpec.html#AppA">
* Java Cryptography Architecture Reference Guide</a>
* for information about standard algorithm names.
*
* @param provider the name of the provider.
*
* @return the new <code>KeyGenerator</code> object.
*
* @exception NullPointerException if the specified algorithm is null.
*
* @exception NoSuchAlgorithmException if a KeyGeneratorSpi
* implementation for the specified algorithm is not
* available from the specified provider.
*
* @exception NoSuchProviderException if the specified provider is not
* registered in the security provider list.
*
* @exception IllegalArgumentException if the <code>provider</code>
* is null or empty.
*
* @see java.security.Provider
*/
public static final KeyGenerator getInstance(String algorithm,
String provider) throws NoSuchAlgorithmException,
NoSuchProviderException {
Instance instance = JceSecurity.getInstance("KeyGenerator",
KeyGeneratorSpi.class, algorithm, provider);
return new KeyGenerator((KeyGeneratorSpi)instance.impl,
instance.provider, algorithm);
}
/**
* Returns a <code>KeyGenerator</code> object that generates secret keys
* for the specified algorithm.
*
* <p> A new KeyGenerator object encapsulating the
* KeyGeneratorSpi implementation from the specified Provider
* object is returned. Note that the specified Provider object
* does not have to be registered in the provider list.
*
* @param algorithm the standard name of the requested key algorithm.
* See Appendix A in the
* <a href=
* "{@docRoot}/../technotes/guides/security/crypto/CryptoSpec.html#AppA">
* Java Cryptography Architecture Reference Guide</a>
* for information about standard algorithm names.
*
* @param provider the provider.
*
* @return the new <code>KeyGenerator</code> object.
*
* @exception NullPointerException if the specified algorithm is null.
*
* @exception NoSuchAlgorithmException if a KeyGeneratorSpi
* implementation for the specified algorithm is not available
* from the specified Provider object.
*
* @exception IllegalArgumentException if the <code>provider</code>
* is null.
*
* @see java.security.Provider
*/
public static final KeyGenerator getInstance(String algorithm,
Provider provider) throws NoSuchAlgorithmException {
Instance instance = JceSecurity.getInstance("KeyGenerator",
KeyGeneratorSpi.class, algorithm, provider);
return new KeyGenerator((KeyGeneratorSpi)instance.impl,
instance.provider, algorithm);
}
/**
* Returns the provider of this <code>KeyGenerator</code> object.
*
* @return the provider of this <code>KeyGenerator</code> object
*/
public final Provider getProvider() {
synchronized (lock) {
disableFailover();
return provider;
}
}
/**
* Update the active spi of this class and return the next
* implementation for failover. If no more implemenations are
* available, this method returns null. However, the active spi of
* this class is never set to null.
*/
private KeyGeneratorSpi nextSpi(KeyGeneratorSpi oldSpi,
boolean reinit) {
synchronized (lock) {
// somebody else did a failover concurrently
// try that spi now
if ((oldSpi != null) && (oldSpi != spi)) {
return spi;
}
if (serviceIterator == null) {
return null;
}
while (serviceIterator.hasNext()) {
Service s = (Service)serviceIterator.next();
if (JceSecurity.canUseProvider(s.getProvider()) == false) {
continue;
}
try {
Object inst = s.newInstance(null);
// ignore non-spis
if (inst instanceof KeyGeneratorSpi == false) {
continue;
}
KeyGeneratorSpi spi = (KeyGeneratorSpi)inst;
if (reinit) {
if (initType == I_SIZE) {
spi.engineInit(initKeySize, initRandom);
} else if (initType == I_PARAMS) {
spi.engineInit(initParams, initRandom);
} else if (initType == I_RANDOM) {
spi.engineInit(initRandom);
} else if (initType != I_NONE) {
throw new AssertionError
("KeyGenerator initType: " + initType);
}
}
provider = s.getProvider();
this.spi = spi;
return spi;
} catch (Exception e) {
// ignore
}
}
disableFailover();
return null;
}
}
void disableFailover() {
serviceIterator = null;
initType = 0;
initParams = null;
initRandom = null;
}
/**
* Initializes this key generator.
*
* @param random the source of randomness for this generator
*/
public final void init(SecureRandom random) {
if (serviceIterator == null) {
spi.engineInit(random);
return;
}
RuntimeException failure = null;
KeyGeneratorSpi mySpi = spi;
do {
try {
mySpi.engineInit(random);
initType = I_RANDOM;
initKeySize = 0;
initParams = null;
initRandom = random;
return;
} catch (RuntimeException e) {
if (failure == null) {
failure = e;
}
mySpi = nextSpi(mySpi, false);
}
} while (mySpi != null);
throw failure;
}
/**
* Initializes this key generator with the specified parameter set.
*
* <p> If this key generator requires any random bytes, it will get them
* using the
* {@link SecureRandom <code>SecureRandom</code>}
* 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.)
*
* @param params the key generation parameters
*
* @exception InvalidAlgorithmParameterException if the given parameters
* are inappropriate for this key generator
*/
public final void init(AlgorithmParameterSpec params)
throws InvalidAlgorithmParameterException
{
init(params, JceSecurity.RANDOM);
}
/**
* Initializes this key generator with the specified parameter
* set and a user-provided source of randomness.
*
* @param params the key generation parameters
* @param random the source of randomness for this key generator
*
* @exception InvalidAlgorithmParameterException if <code>params</code> is
* inappropriate for this key generator
*/
public final void init(AlgorithmParameterSpec params, SecureRandom random)
throws InvalidAlgorithmParameterException
{
if (serviceIterator == null) {
spi.engineInit(params, random);
return;
}
Exception failure = null;
KeyGeneratorSpi mySpi = spi;
do {
try {
mySpi.engineInit(params, random);
initType = I_PARAMS;
initKeySize = 0;
initParams = params;
initRandom = random;
return;
} catch (Exception e) {
if (failure == null) {
failure = e;
}
mySpi = nextSpi(mySpi, false);
}
} while (mySpi != null);
if (failure instanceof InvalidAlgorithmParameterException) {
throw (InvalidAlgorithmParameterException)failure;
}
if (failure instanceof RuntimeException) {
throw (RuntimeException)failure;
}
throw new InvalidAlgorithmParameterException("init() failed", failure);
}
/**
* Initializes this key generator for a certain keysize.
*
* <p> If this key generator requires any random bytes, it will get them
* using the
* {@link SecureRandom <code>SecureRandom</code>}
* 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.)
*
* @param keysize the keysize. This is an algorithm-specific metric,
* specified in number of bits.
*
* @exception InvalidParameterException if the keysize is wrong or not
* supported.
*/
public final void init(int keysize) {
init(keysize, JceSecurity.RANDOM);
}
/**
* Initializes this key generator for a certain keysize, using a
* user-provided source of randomness.
*
* @param keysize the keysize. This is an algorithm-specific metric,
* specified in number of bits.
* @param random the source of randomness for this key generator
*
* @exception InvalidParameterException if the keysize is wrong or not
* supported.
*/
public final void init(int keysize, SecureRandom random) {
if (serviceIterator == null) {
spi.engineInit(keysize, random);
return;
}
RuntimeException failure = null;
KeyGeneratorSpi mySpi = spi;
do {
try {
mySpi.engineInit(keysize, random);
initType = I_SIZE;
initKeySize = keysize;
initParams = null;
initRandom = random;
return;
} catch (RuntimeException e) {
if (failure == null) {
failure = e;
}
mySpi = nextSpi(mySpi, false);
}
} while (mySpi != null);
throw failure;
}
/**
* Generates a secret key.
*
* @return the new key
*/
public final SecretKey generateKey() {
if (serviceIterator == null) {
return spi.engineGenerateKey();
}
RuntimeException failure = null;
KeyGeneratorSpi mySpi = spi;
do {
try {
return mySpi.engineGenerateKey();
} catch (RuntimeException e) {
if (failure == null) {
failure = e;
}
mySpi = nextSpi(mySpi, true);
}
} while (mySpi != null);
throw failure;
}
}