395 lines
16 KiB
Java
395 lines
16 KiB
Java
package javax.crypto;
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import java.security.Key;
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import java.security.Provider;
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import java.security.SecureRandom;
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import java.security.InvalidKeyException;
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import java.security.NoSuchProviderException;
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import java.security.NoSuchAlgorithmException;
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import java.security.InvalidAlgorithmParameterException;
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import java.security.spec.AlgorithmParameterSpec;
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/**
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* This class provides the functionality of a key agreement (or key
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* exchange) protocol.
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* The keys involved in establishing a shared secret are created by one of the
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* key generators (<code>KeyPairGenerator</code> or
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* <code>KeyGenerator</code>), a <code>KeyFactory</code>, or as a result from
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* an intermediate phase of the key agreement protocol
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* (see <a href = "#doPhase(java.security.Key, boolean)">doPhase</a>).
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*
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* For each of the correspondents in the key exchange, <code>doPhase</code>
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* needs to be called. For example, if this key exchange is with one other
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* party, <code>doPhase</code> needs to be called once, with the
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* <code>lastPhase</code> flag set to <code>true</code>.
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* If this key exchange is
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* with two other parties, <code>doPhase</code> needs to be called twice,
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* the first time setting the <code>lastPhase</code> flag to
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* <code>false</code>, and the second time setting it to <code>true</code>.
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* There may be any number of parties involved in a key exchange.
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*
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* @see KeyGenerator
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* @see SecretKey
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*/
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public class KeyAgreement
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{
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KeyAgreementSpi keyAgreeSpi;
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Provider provider;
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String algorithm;
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/**
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* Creates a KeyAgreement object.
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*
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* @param keyAgreeSpi the delegate
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* @param provider the provider
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* @param algorithm the algorithm
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*/
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protected KeyAgreement(
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KeyAgreementSpi keyAgreeSpi,
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Provider provider,
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String algorithm)
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{
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this.keyAgreeSpi = keyAgreeSpi;
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this.provider = provider;
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this.algorithm = algorithm;
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}
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/**
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* Returns the algorithm name of this <code>KeyAgreement</code> object.
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* <p>
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* This is the same name that was specified in one of the
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* <code>getInstance</code> calls that created this
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* <code>KeyAgreement</code> object.
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*
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* @return the algorithm name of this <code>KeyAgreement</code> object.
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*/
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public final String getAlgorithm()
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{
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return algorithm;
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}
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/**
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* Generates a <code>KeyAgreement</code> object that implements the
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* specified key agreement algorithm.
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* If the default provider package provides an implementation of the
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* requested key agreement algorithm, an instance of
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* <code>KeyAgreement</code> containing that implementation is returned.
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* If the algorithm is not available in the default provider package,
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* other provider packages are searched.
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*
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* @param algorithm the standard name of the requested key agreement algorithm.
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* See Appendix A in the Java Cryptography Extension API Specification & Reference
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* for information about standard algorithm names.
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* @return the new <code>KeyAgreement</code> object
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* @exception NoSuchAlgorithmException if the specified algorithm is not
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* available in the default provider package or any of the other provider
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* packages that were searched.
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*/
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public static final KeyAgreement getInstance(
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String algorithm)
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throws NoSuchAlgorithmException
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{
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try
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{
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JCEUtil.Implementation imp = JCEUtil.getImplementation("KeyAgreement", algorithm, (String) null);
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if (imp == null)
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{
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throw new NoSuchAlgorithmException(algorithm + " not found");
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}
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KeyAgreement keyAgree = new KeyAgreement((KeyAgreementSpi)imp.getEngine(), imp.getProvider(), algorithm);
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return keyAgree;
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}
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catch (NoSuchProviderException e)
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{
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throw new NoSuchAlgorithmException(algorithm + " not found");
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}
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}
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/**
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* Generates a <code>KeyAgreement</code> object for the specified key
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* agreement algorithm from the specified provider.
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*
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* @param algorithm the standard name of the requested key agreement algorithm.
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* See Appendix A in the Java Cryptography Extension API Specification & Reference
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* for information about standard algorithm names.
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* @param provider the provider
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* @return the new <code>KeyAgreement</code> object
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* @exception NoSuchAlgorithmException if the specified algorithm is not
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* available from the specified provider.
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*/
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public static final KeyAgreement getInstance(
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String algorithm,
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Provider provider)
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throws NoSuchAlgorithmException
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{
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if (provider == null)
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{
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throw new IllegalArgumentException("No provider specified to KeyAgreement.getInstance()");
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}
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JCEUtil.Implementation imp = JCEUtil.getImplementation("KeyAgreement", algorithm, provider);
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if (imp == null)
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{
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throw new NoSuchAlgorithmException(algorithm + " not found");
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}
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KeyAgreement keyAgree = new KeyAgreement((KeyAgreementSpi)imp.getEngine(), imp.getProvider(), algorithm);
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return keyAgree;
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}
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/**
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* Generates a <code>KeyAgreement</code> object for the specified key
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* agreement algorithm from the specified provider.
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*
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* @param algorithm the standard name of the requested key agreement algorithm.
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* See Appendix A in the Java Cryptography Extension API Specification & Reference
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* for information about standard algorithm names.
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* @param provider the name of the provider
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* @return the new <code>KeyAgreement</code> object
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* @exception NoSuchAlgorithmException if the specified algorithm is not
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* available from the specified provider.
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* @exception NoSuchProviderException if the specified provider has not
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* been configured.
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*/
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public static final KeyAgreement getInstance(
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String algorithm,
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String provider)
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throws NoSuchAlgorithmException, NoSuchProviderException
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{
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if (provider == null)
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{
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throw new IllegalArgumentException("No provider specified to KeyAgreement.getInstance()");
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}
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JCEUtil.Implementation imp = JCEUtil.getImplementation("KeyAgreement", algorithm, provider);
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if (imp == null)
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{
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throw new NoSuchAlgorithmException(algorithm + " not found");
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}
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KeyAgreement keyAgree = new KeyAgreement((KeyAgreementSpi)imp.getEngine(), imp.getProvider(), algorithm);
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return keyAgree;
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}
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/**
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* Returns the provider of this <code>KeyAgreement</code> object.
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*
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* @return the provider of this <code>KeyAgreement</code> object
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*/
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public final Provider getProvider()
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{
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return provider;
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}
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/**
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* Initializes this key agreement with the given key, which is required to
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* contain all the algorithm parameters required for this key agreement.
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* <p>
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* If this key agreement requires any random bytes, it will get
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* them using the <a href="http://java.sun.com/products/jdk/1.2/docs/api/java.security.SecureRandom.html">
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* <code>SecureRandom</code></a> implementation of the highest-priority
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* installed provider as the source of randomness.
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* (If none of the installed providers supply an implementation of
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* SecureRandom, a system-provided source of randomness will be used.)
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*
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* @param key the party's private information. For example, in the case
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* of the Diffie-Hellman key agreement, this would be the party's own
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* Diffie-Hellman private key.
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* @exception InvalidKeyException if the given key is
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* inappropriate for this key agreement, e.g., is of the wrong type or
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* has an incompatible algorithm type.
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*/
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public final void init(
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Key key)
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throws InvalidKeyException
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{
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keyAgreeSpi.engineInit(key, null);
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}
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/**
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* Initializes this key agreement with the given key and source of
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* randomness. The given key is required to contain all the algorithm
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* parameters required for this key agreement.
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* <p>
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* If the key agreement algorithm requires random bytes, it gets them
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* from the given source of randomness, <code>random</code>.
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* However, if the underlying
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* algorithm implementation does not require any random bytes,
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* <code>random</code> is ignored.
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*
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* @param key the party's private information. For example, in the case
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* of the Diffie-Hellman key agreement, this would be the party's own
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* Diffie-Hellman private key.
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* @param random the source of randomness
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* @exception InvalidKeyException if the given key is
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* inappropriate for this key agreement, e.g., is of the wrong type or
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* has an incompatible algorithm type.
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*/
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public final void init(
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Key key,
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SecureRandom random)
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throws InvalidKeyException
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{
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keyAgreeSpi.engineInit(key, random);
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}
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/**
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* Initializes this key agreement with the given key and set of
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* algorithm parameters.
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* <p>
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* If this key agreement requires any random bytes, it will get
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* them using the <a href="http://java.sun.com/products/jdk/1.2/docs/api/java.security.SecureRandom.html">
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* <code>SecureRandom</code></a> implementation of the highest-priority
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* installed provider as the source of randomness.
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* (If none of the installed providers supply an implementation of
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* SecureRandom, a system-provided source of randomness will be used.)
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*
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* @param key the party's private information. For example, in the case
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* of the Diffie-Hellman key agreement, this would be the party's own
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* Diffie-Hellman private key.
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* @param params the key agreement parameters
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* @exception InvalidKeyException if the given key is inappropriate for this
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* key agreement, e.g., is of the wrong type or has an incompatible algorithm type.
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* @exception InvalidAlgorithmParameterException if the given parameters
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* are inappropriate for this key agreement.
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*/
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public final void init(
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Key key,
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AlgorithmParameterSpec params)
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throws InvalidKeyException, InvalidAlgorithmParameterException
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{
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keyAgreeSpi.engineInit(key, params, null);
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}
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/**
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* Initializes this key agreement with the given key, set of
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* algorithm parameters, and source of randomness.
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*
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* @param key the party's private information. For example, in the case
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* of the Diffie-Hellman key agreement, this would be the party's own
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* Diffie-Hellman private key.
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* @param params the key agreement parameters
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* @param random the source of randomness
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* @exception InvalidKeyException if the given key is
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* inappropriate for this key agreement, e.g., is of the wrong type or
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* has an incompatible algorithm type.
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* @exception InvalidAlgorithmParameterException if the given parameters
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* are inappropriate for this key agreement.
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*/
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public final void init(
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Key key,
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AlgorithmParameterSpec params,
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SecureRandom random)
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throws InvalidKeyException, InvalidAlgorithmParameterException
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{
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keyAgreeSpi.engineInit(key, params, random);
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}
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/**
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* Executes the next phase of this key agreement with the given
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* key that was received from one of the other parties involved in this key
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* agreement.
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*
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* @param key the key for this phase. For example, in the case of
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* Diffie-Hellman between 2 parties, this would be the other party's
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* Diffie-Hellman public key.
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* @param lastPhase flag which indicates whether or not this is the last
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* phase of this key agreement.
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* @return the (intermediate) key resulting from this phase, or null
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* if this phase does not yield a key
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* @exception InvalidKeyException if the given key is inappropriate for this phase.
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* @exception IllegalStateException if this key agreement has not been
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* initialized.
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*/
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public final Key doPhase(
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Key key,
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boolean lastPhase)
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throws InvalidKeyException, IllegalStateException
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{
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return keyAgreeSpi.engineDoPhase(key, lastPhase);
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}
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/**
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* Generates the shared secret and returns it in a new buffer.
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* <p>
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* This method resets this <code>KeyAgreement</code> object, so that it
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* can be reused for further key agreements. Unless this key agreement is
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* reinitialized with one of the <code>init</code> methods, the same
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* private information and algorithm parameters will be used for
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* subsequent key agreements.
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*
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* @return the new buffer with the shared secret
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* @exception IllegalStateException if this key agreement has not been completed yet
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*/
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public final byte[] generateSecret()
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throws IllegalStateException
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{
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return keyAgreeSpi.engineGenerateSecret();
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}
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/**
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* Generates the shared secret, and places it into the buffer
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* <code>sharedSecret</code>, beginning at <code>offset</code> inclusive.
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* <p>
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* If the <code>sharedSecret</code> buffer is too small to hold the
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* result, a <code>ShortBufferException</code> is thrown.
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* In this case, this call should be repeated with a larger output buffer.
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* <p>
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* This method resets this <code>KeyAgreement</code> object, so that it
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* can be reused for further key agreements. Unless this key agreement is
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* reinitialized with one of the <code>init</code> methods, the same
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* private information and algorithm parameters will be used for
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* subsequent key agreements.
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*
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* @param sharedSecret the buffer for the shared secret
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* @param offset the offset in <code>sharedSecret</code> where the
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* shared secret will be stored
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* @return the number of bytes placed into <code>sharedSecret</code>
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* @exception IllegalStateException if this key agreement has not been
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* completed yet
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* @exception ShortBufferException if the given output buffer is too small
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* to hold the secret
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*/
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public final int generateSecret(
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byte[] sharedSecret,
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int offset)
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throws IllegalStateException, ShortBufferException
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{
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return keyAgreeSpi.engineGenerateSecret(sharedSecret, offset);
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}
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/**
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* Creates the shared secret and returns it as a <code>SecretKey</code>
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* object of the specified algorithm.
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* <p>
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* This method resets this <code>KeyAgreement</code> object, so that it
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* can be reused for further key agreements. Unless this key agreement is
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* reinitialized with one of the <code>init</code> methods, the same
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* private information and algorithm parameters will be used for
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* subsequent key agreements.
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*
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* @param algorithm the requested secret-key algorithm
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* @return the shared secret key
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* @exception IllegalStateException if this key agreement has not been
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* completed yet
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* @exception NoSuchAlgorithmException if the specified secret-key
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* algorithm is not available
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* @exception InvalidKeyException if the shared secret-key material cannot
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* be used to generate a secret key of the specified algorithm (e.g.,
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* the key material is too short)
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*/
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public final SecretKey generateSecret(
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String algorithm)
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throws IllegalStateException, NoSuchAlgorithmException, InvalidKeyException
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{
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return keyAgreeSpi.engineGenerateSecret(algorithm);
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}
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}
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