站内搜索: 请输入搜索关键词
当前页面: 在线文档首页 > JDK 5 Documentation v1.5.0, Java 2 SDK 英文文档

KeyAgreement (Java 2 Platform SE 5.0) - JDK 5 Documentation v1.5.0, Java 2 SDK 英文文档

Overview  Package   Class  Use  Tree  Deprecated  Index  Help 
JavaTM 2 Platform
Standard Ed. 5.0
 PREV CLASS   NEXT CLASS FRAMES    NO FRAMES    
SUMMARY: NESTED | FIELD | CONSTR | METHOD DETAIL: FIELD | CONSTR | METHOD

javax.crypto
Class KeyAgreement

java.lang.Object
  extended by javax.crypto.KeyAgreement

public class KeyAgreement
extends Object

This class provides the functionality of a key agreement (or key exchange) protocol. The keys involved in establishing a shared secret are created by one of the key generators (KeyPairGenerator or KeyGenerator), a KeyFactory, or as a result from an intermediate phase of the key agreement protocol For each of the correspondents in the key exchange, doPhase needs to be called. For example, if this key exchange is with one other party, doPhase needs to be called once, with the lastPhase flag set to true. If this key exchange is with two other parties, doPhase needs to be called twice, the first time setting the lastPhase flag to false, and the second time setting it to true. There may be any number of parties involved in a key exchange.

Since:
1.4
See Also:
KeyGenerator, SecretKey

Constructor Summary
protected KeyAgreement(KeyAgreementSpi keyAgreeSpi, Provider provider, String algorithm)
          Creates a KeyAgreement object.
 
Method Summary
 Key doPhase(Key key, boolean lastPhase)
          Executes the next phase of this key agreement with the given key that was received from one of the other parties involved in this key agreement.
 byte[] generateSecret()
          Generates the shared secret and returns it in a new buffer.
 int generateSecret(byte[] sharedSecret, int offset)
          Generates the shared secret, and places it into the buffer sharedSecret, beginning at offset inclusive.
 SecretKey generateSecret(String algorithm)
          Creates the shared secret and returns it as a SecretKey object of the specified algorithm.
 String getAlgorithm()
          Returns the algorithm name of this KeyAgreement object.
static KeyAgreement getInstance(String algorithm)
          Generates a KeyAgreement object that implements the specified key agreement algorithm.
static KeyAgreement getInstance(String algorithm, Provider provider)
          Generates a KeyAgreement object for the specified key agreement algorithm from the specified provider.
static KeyAgreement getInstance(String algorithm, String provider)
          Generates a KeyAgreement object for the specified key agreement algorithm from the specified provider.
 Provider getProvider()
          Returns the provider of this KeyAgreement object.
 void init(Key key)
          Initializes this key agreement with the given key, which is required to contain all the algorithm parameters required for this key agreement.
 void init(Key key, AlgorithmParameterSpec params)
          Initializes this key agreement with the given key and set of algorithm parameters.
 void init(Key key, AlgorithmParameterSpec params, SecureRandom random)
          Initializes this key agreement with the given key, set of algorithm parameters, and source of randomness.
 void init(Key key, SecureRandom random)
          Initializes this key agreement with the given key and source of randomness.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

KeyAgreement

protected KeyAgreement(KeyAgreementSpi keyAgreeSpi,
                       Provider provider,
                       String algorithm)
Creates a KeyAgreement object.

Parameters:
keyAgreeSpi - the delegate
provider - the provider
algorithm - the algorithm
Method Detail

getAlgorithm

public final String getAlgorithm()
Returns the algorithm name of this KeyAgreement object.

This is the same name that was specified in one of the getInstance calls that created this KeyAgreement object.

Returns:
the algorithm name of this KeyAgreement object.

getInstance

public static final KeyAgreement getInstance(String algorithm)
                                      throws NoSuchAlgorithmException
Generates a KeyAgreement object that implements the specified key agreement algorithm. If the default provider package provides an implementation of the requested key agreement algorithm, an instance of KeyAgreement containing that implementation is returned. If the algorithm is not available in the default provider package, other provider packages are searched.

Parameters:
algorithm - the standard name of the requested key agreement algorithm. See Appendix A in the Java Cryptography Extension Reference Guide for information about standard algorithm names.
Returns:
the new KeyAgreement object
Throws:
NullPointerException - if the specified algorithm is null.
NoSuchAlgorithmException - if the specified algorithm is not available in the default provider package or any of the other provider packages that were searched.

getInstance

public static final KeyAgreement getInstance(String algorithm,
                                             String provider)
                                      throws NoSuchAlgorithmException,
                                             NoSuchProviderException
Generates a KeyAgreement object for the specified key agreement algorithm from the specified provider.

Parameters:
algorithm - the standard name of the requested key agreement algorithm. See Appendix A in the Java Cryptography Extension Reference Guide for information about standard algorithm names.
provider - the name of the provider
Returns:
the new KeyAgreement object
Throws:
NullPointerException - if the specified algorithm is null.
NoSuchAlgorithmException - if the specified algorithm is not available from the specified provider.
NoSuchProviderException - if the specified provider has not been configured.
IllegalArgumentException - if the provider is null.

getInstance

public static final KeyAgreement getInstance(String algorithm,
                                             Provider provider)
                                      throws NoSuchAlgorithmException
Generates a KeyAgreement object for the specified key agreement algorithm from the specified provider. Note: the provider doesn't have to be registered.

Parameters:
algorithm - the standard name of the requested key agreement algorithm. See Appendix A in the Java Cryptography Extension Reference Guide for information about standard algorithm names.
provider - the provider
Returns:
the new KeyAgreement object
Throws:
NullPointerException - if the specified algorithm is null.
NoSuchAlgorithmException - if the specified algorithm is not available from the specified provider.
IllegalArgumentException - if the provider is null.

getProvider

public final Provider getProvider()
Returns the provider of this KeyAgreement object.

Returns:
the provider of this KeyAgreement object

init

public final void init(Key key)
                throws InvalidKeyException
Initializes this key agreement with the given key, which is required to contain all the algorithm parameters required for this key agreement.

If this key agreement requires any random bytes, it will get them using the SecureRandom 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.)

Parameters:
key - the party's private information. For example, in the case of the Diffie-Hellman key agreement, this would be the party's own Diffie-Hellman private key.
Throws:
InvalidKeyException - if the given key is inappropriate for this key agreement, e.g., is of the wrong type or has an incompatible algorithm type.

init

public final void init(Key key,
                       SecureRandom random)
                throws InvalidKeyException
Initializes this key agreement with the given key and source of randomness. The given key is required to contain all the algorithm parameters required for this key agreement.

If the key agreement algorithm requires random bytes, it gets them from the given source of randomness, random. However, if the underlying algorithm implementation does not require any random bytes, random is ignored.

Parameters:
key - the party's private information. For example, in the case of the Diffie-Hellman key agreement, this would be the party's own Diffie-Hellman private key.
random - the source of randomness
Throws:
InvalidKeyException - if the given key is inappropriate for this key agreement, e.g., is of the wrong type or has an incompatible algorithm type.

init

public final void init(Key key,
                       AlgorithmParameterSpec params)
                throws InvalidKeyException,
                       InvalidAlgorithmParameterException
Initializes this key agreement with the given key and set of algorithm parameters.

If this key agreement requires any random bytes, it will get them using the SecureRandom 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.)

Parameters:
key - the party's private information. For example, in the case of the Diffie-Hellman key agreement, this would be the party's own Diffie-Hellman private key.
params - the key agreement parameters
Throws:
InvalidKeyException - if the given key is inappropriate for this key agreement, e.g., is of the wrong type or has an incompatible algorithm type.
InvalidAlgorithmParameterException - if the given parameters are inappropriate for this key agreement.

init

public final void init(Key key,
                       AlgorithmParameterSpec params,
                       SecureRandom random)
                throws InvalidKeyException,
                       InvalidAlgorithmParameterException
Initializes this key agreement with the given key, set of algorithm parameters, and source of randomness.

Parameters:
key - the party's private information. For example, in the case of the Diffie-Hellman key agreement, this would be the party's own Diffie-Hellman private key.
params - the key agreement parameters
random - the source of randomness
Throws:
InvalidKeyException - if the given key is inappropriate for this key agreement, e.g., is of the wrong type or has an incompatible algorithm type.
InvalidAlgorithmParameterException - if the given parameters are inappropriate for this key agreement.

doPhase

public final Key doPhase(Key key,
                         boolean lastPhase)
                  throws InvalidKeyException,
                         IllegalStateException
Executes the next phase of this key agreement with the given key that was received from one of the other parties involved in this key agreement.

Parameters:
key - the key for this phase. For example, in the case of Diffie-Hellman between 2 parties, this would be the other party's Diffie-Hellman public key.
lastPhase - flag which indicates whether or not this is the last phase of this key agreement.
Returns:
the (intermediate) key resulting from this phase, or null if this phase does not yield a key
Throws:
InvalidKeyException - if the given key is inappropriate for this phase.
IllegalStateException - if this key agreement has not been initialized.

generateSecret

public final byte[] generateSecret()
                            throws IllegalStateException
Generates the shared secret and returns it in a new buffer.

This method resets this KeyAgreement object, so that it can be reused for further key agreements. Unless this key agreement is reinitialized with one of the init methods, the same private information and algorithm parameters will be used for subsequent key agreements.

Returns:
the new buffer with the shared secret
Throws:
IllegalStateException - if this key agreement has not been completed yet

generateSecret

public final int generateSecret(byte[] sharedSecret,
                                int offset)
                         throws IllegalStateException,
                                ShortBufferException
Generates the shared secret, and places it into the buffer sharedSecret, beginning at offset inclusive.

If the sharedSecret buffer is too small to hold the result, a ShortBufferException is thrown. In this case, this call should be repeated with a larger output buffer.

This method resets this KeyAgreement object, so that it can be reused for further key agreements. Unless this key agreement is reinitialized with one of the init methods, the same private information and algorithm parameters will be used for subsequent key agreements.

Parameters:
sharedSecret - the buffer for the shared secret
offset - the offset in sharedSecret where the shared secret will be stored
Returns:
the number of bytes placed into sharedSecret
Throws:
IllegalStateException - if this key agreement has not been completed yet
ShortBufferException - if the given output buffer is too small to hold the secret

generateSecret

public final SecretKey generateSecret(String algorithm)
                               throws IllegalStateException,
                                      NoSuchAlgorithmException,
                                      InvalidKeyException
Creates the shared secret and returns it as a SecretKey object of the specified algorithm.

This method resets this KeyAgreement object, so that it can be reused for further key agreements. Unless this key agreement is reinitialized with one of the init methods, the same private information and algorithm parameters will be used for subsequent key agreements.

Parameters:
algorithm - the requested secret-key algorithm
Returns:
the shared secret key
Throws:
IllegalStateException - if this key agreement has not been completed yet
NoSuchAlgorithmException - if the specified secret-key algorithm is not available
InvalidKeyException - if the shared secret-key material cannot be used to generate a secret key of the specified algorithm (e.g., the key material is too short)
Overview  Package   Class  Use  Tree  Deprecated  Index  Help 
JavaTM 2 Platform
Standard Ed. 5.0
 PREV CLASS   NEXT CLASS FRAMES    NO FRAMES    
SUMMARY: NESTED | FIELD | CONSTR | METHOD DETAIL: FIELD | CONSTR | METHOD
Submit a bug or feature
For further API reference and developer documentation, see Java 2 SDK SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

Copyright 2004 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.