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/* * @(#)KeyFactory.java 1.35 06/04/21 * * Copyright 2006 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ package java.security; import java.util.*; import java.security.Provider.Service; import java.security.spec.KeySpec; import java.security.spec.InvalidKeySpecException; import sun.security.util.Debug; import sun.security.jca.*; import sun.security.jca.GetInstance.Instance; /** * Key factories are used to convert <I>keys</I> (opaque * cryptographic keys of type <code>Key</code>) into <I>key specifications</I> * (transparent representations of the underlying key material), and vice * versa. * * <P> Key factories are bi-directional. That is, they allow you to build an * opaque key object from a given key specification (key material), or to * retrieve the underlying key material of a key object in a suitable format. * * <P> Multiple compatible key specifications may exist for the same key. * For example, a DSA public key may be specified using * <code>DSAPublicKeySpec</code> or * <code>X509EncodedKeySpec</code>. A key factory can be used to translate * between compatible key specifications. * * <P> The following is an example of how to use a key factory in order to * instantiate a DSA public key from its encoding. * Assume Alice has received a digital signature from Bob. * Bob also sent her his public key (in encoded format) to verify * his signature. Alice then performs the following actions: * * <pre> * X509EncodedKeySpec bobPubKeySpec = new X509EncodedKeySpec(bobEncodedPubKey); * KeyFactory keyFactory = KeyFactory.getInstance("DSA"); * PublicKey bobPubKey = keyFactory.generatePublic(bobPubKeySpec); * Signature sig = Signature.getInstance("DSA"); * sig.initVerify(bobPubKey); * sig.update(data); * sig.verify(signature); * </pre> * * @author Jan Luehe * * @version 1.35, 04/21/06 * * @see Key * @see PublicKey * @see PrivateKey * @see java.security.spec.KeySpec * @see java.security.spec.DSAPublicKeySpec * @see java.security.spec.X509EncodedKeySpec * * @since 1.2 */ public class KeyFactory { private static final Debug debug = Debug.getInstance("jca", "KeyFactory"); // The algorithm associated with this key factory private final String algorithm; // The provider private Provider provider; // The provider implementation (delegate) private volatile KeyFactorySpi spi; // lock for mutex during provider selection private final Object lock = new Object(); // remaining services to try in provider selection // null once provider is selected private Iterator<Service> serviceIterator; /** * Creates a KeyFactory object. * * @param keyFacSpi the delegate * @param provider the provider * @param algorithm the name of the algorithm * to associate with this <tt>KeyFactory</tt> */ protected KeyFactory(KeyFactorySpi keyFacSpi, Provider provider, String algorithm) { this.spi = keyFacSpi; this.provider = provider; this.algorithm = algorithm; } private KeyFactory(String algorithm) throws NoSuchAlgorithmException { this.algorithm = algorithm; List<Service> list = GetInstance.getServices("KeyFactory", algorithm); serviceIterator = list.iterator(); // fetch and instantiate initial spi if (nextSpi(null) == null) { throw new NoSuchAlgorithmException (algorithm + " KeyFactory not available"); } } /** * Returns a KeyFactory object that converts * public/private keys of the specified algorithm. * * <p> This method traverses the list of registered security Providers, * starting with the most preferred Provider. * A new KeyFactory object encapsulating the * KeyFactorySpi 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 name of the requested key algorithm. * See Appendix A in the <a href= * "../../../technotes/guides/security/crypto/CryptoSpec.html#AppA"> * Java Cryptography Architecture API Specification & Reference </a> * for information about standard algorithm names. * * @return the new KeyFactory object. * * @exception NoSuchAlgorithmException if no Provider supports a * KeyFactorySpi implementation for the * specified algorithm. * * @see Provider */ public static KeyFactory getInstance(String algorithm) throws NoSuchAlgorithmException { return new KeyFactory(algorithm); } /** * Returns a KeyFactory object that converts * public/private keys of the specified algorithm. * * <p> A new KeyFactory object encapsulating the * KeyFactorySpi 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 name of the requested key algorithm. * See Appendix A in the <a href= * "../../../technotes/guides/security/crypto/CryptoSpec.html#AppA"> * Java Cryptography Architecture API Specification & Reference </a> * for information about standard algorithm names. * * @param provider the name of the provider. * * @return the new KeyFactory object. * * @exception NoSuchAlgorithmException if a KeyFactorySpi * 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 provider name is null * or empty. * * @see Provider */ public static KeyFactory getInstance(String algorithm, String provider) throws NoSuchAlgorithmException, NoSuchProviderException { Instance instance = GetInstance.getInstance("KeyFactory", KeyFactorySpi.class, algorithm, provider); return new KeyFactory((KeyFactorySpi)instance.impl, instance.provider, algorithm); } /** * Returns a KeyFactory object that converts * public/private keys of the specified algorithm. * * <p> A new KeyFactory object encapsulating the * KeyFactorySpi 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 name of the requested key algorithm. * See Appendix A in the <a href= * "../../../technotes/guides/security/crypto/CryptoSpec.html#AppA"> * Java Cryptography Architecture API Specification & Reference </a> * for information about standard algorithm names. * * @param provider the provider. * * @return the new KeyFactory object. * * @exception NoSuchAlgorithmException if a KeyFactorySpi * implementation for the specified algorithm is not available * from the specified Provider object. * * @exception IllegalArgumentException if the specified provider is null. * * @see Provider * * @since 1.4 */ public static KeyFactory getInstance(String algorithm, Provider provider) throws NoSuchAlgorithmException { Instance instance = GetInstance.getInstance("KeyFactory", KeyFactorySpi.class, algorithm, provider); return new KeyFactory((KeyFactorySpi)instance.impl, instance.provider, algorithm); } /** * Returns the provider of this key factory object. * * @return the provider of this key factory object */ public final Provider getProvider() { synchronized (lock) { // disable further failover after this call serviceIterator = null; return provider; } } /** * Gets the name of the algorithm * associated with this <tt>KeyFactory</tt>. * * @return the name of the algorithm associated with this * <tt>KeyFactory</tt> */ public final String getAlgorithm() { return this.algorithm; } /** * Update the active KeyFactorySpi 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 KeyFactorySpi nextSpi(KeyFactorySpi oldSpi) { 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 = serviceIterator.next(); try { Object obj = s.newInstance(null); if (obj instanceof KeyFactorySpi == false) { continue; } KeyFactorySpi spi = (KeyFactorySpi)obj; provider = s.getProvider(); this.spi = spi; return spi; } catch (NoSuchAlgorithmException e) { // ignore } } serviceIterator = null; return null; } } /** * Generates a public key object from the provided key specification * (key material). * * @param keySpec the specification (key material) of the public key. * * @return the public key. * * @exception InvalidKeySpecException if the given key specification * is inappropriate for this key factory to produce a public key. */ public final PublicKey generatePublic(KeySpec keySpec) throws InvalidKeySpecException { if (serviceIterator == null) { return spi.engineGeneratePublic(keySpec); } Exception failure = null; KeyFactorySpi mySpi = spi; do { try { return mySpi.engineGeneratePublic(keySpec); } catch (Exception e) { if (failure == null) { failure = e; } mySpi = nextSpi(mySpi); } } while (mySpi != null); if (failure instanceof RuntimeException) { throw (RuntimeException)failure; } if (failure instanceof InvalidKeySpecException) { throw (InvalidKeySpecException)failure; } throw new InvalidKeySpecException ("Could not generate public key", failure); } /** * Generates a private key object from the provided key specification * (key material). * * @param keySpec the specification (key material) of the private key. * * @return the private key. * * @exception InvalidKeySpecException if the given key specification * is inappropriate for this key factory to produce a private key. */ public final PrivateKey generatePrivate(KeySpec keySpec) throws InvalidKeySpecException { if (serviceIterator == null) { return spi.engineGeneratePrivate(keySpec); } Exception failure = null; KeyFactorySpi mySpi = spi; do { try { return mySpi.engineGeneratePrivate(keySpec); } catch (Exception e) { if (failure == null) { failure = e; } mySpi = nextSpi(mySpi); } } while (mySpi != null); if (failure instanceof RuntimeException) { throw (RuntimeException)failure; } if (failure instanceof InvalidKeySpecException) { throw (InvalidKeySpecException)failure; } throw new InvalidKeySpecException ("Could not generate private key", failure); } /** * Returns a specification (key material) of the given key object. * <code>keySpec</code> identifies the specification class in which * the key material should be returned. It could, for example, be * <code>DSAPublicKeySpec.class</code>, to indicate that the * key material should be returned in an instance of the * <code>DSAPublicKeySpec</code> class. * * @param key the key. * * @param keySpec the specification class in which * the key material should be returned. * * @return the underlying key specification (key material) in an instance * of the requested specification class. * * @exception InvalidKeySpecException if the requested key specification is * inappropriate for the given key, or the given key cannot be processed * (e.g., the given key has an unrecognized algorithm or format). */ public final <T extends KeySpec> T getKeySpec(Key key, Class<T> keySpec) throws InvalidKeySpecException { if (serviceIterator == null) { return spi.engineGetKeySpec(key, keySpec); } Exception failure = null; KeyFactorySpi mySpi = spi; do { try { return mySpi.engineGetKeySpec(key, keySpec); } catch (Exception e) { if (failure == null) { failure = e; } mySpi = nextSpi(mySpi); } } while (mySpi != null); if (failure instanceof RuntimeException) { throw (RuntimeException)failure; } if (failure instanceof InvalidKeySpecException) { throw (InvalidKeySpecException)failure; } throw new InvalidKeySpecException ("Could not get key spec", failure); } /** * Translates a key object, whose provider may be unknown or potentially * untrusted, into a corresponding key object of this key factory. * * @param key the key whose provider is unknown or untrusted. * * @return the translated key. * * @exception InvalidKeyException if the given key cannot be processed * by this key factory. */ public final Key translateKey(Key key) throws InvalidKeyException { if (serviceIterator == null) { return spi.engineTranslateKey(key); } Exception failure = null; KeyFactorySpi mySpi = spi; do { try { return mySpi.engineTranslateKey(key); } catch (Exception e) { if (failure == null) { failure = e; } mySpi = nextSpi(mySpi); } } while (mySpi != null); if (failure instanceof RuntimeException) { throw (RuntimeException)failure; } if (failure instanceof InvalidKeyException) { throw (InvalidKeyException)failure; } throw new InvalidKeyException ("Could not translate key", failure); } }