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java.lang.Object | +--javax.crypto.KeyAgreement
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 (see doPhase). 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.
AlgorithmParameterGenerator
,
AlgorithmParameters
,
java.security.KeyPairGenerator
,
Key
,
KeyFactory
,
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. |
SecretKey |
generateSecret(String algorithm)
Creates the shared secret and returns it as a secret key object of the requested algorithm type. |
String |
getAlgorithm()
Returns the standard name of the key agreement algorithm. |
static KeyAgreement |
getInstance(String algorithm)
Generates a KeyAgreement object that implements the specified key agreement algorithm. |
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 |
protected KeyAgreement(KeyAgreementSpi keyAgreeSpi, Provider provider, String algorithm)
keyAgreeSpi
- the delegateprovider
- the provideralgorithm
- the algorithmMethod Detail |
public final String getAlgorithm()
public static final KeyAgreement getInstance(String algorithm) throws NoSuchAlgorithmException
algorithm
- the standard name of the requested key
agreement algorithm. See Appendix A in the Java
Cryptography Extension API Specification & Reference for
information about standard algorithm names.public static final KeyAgreement getInstance(String algorithm, String provider) throws NoSuchAlgorithmException, NoSuchProviderException
algorithm
- the standard name of the requested key
agreement algorithm. See Appendix A in the Java
Cryptography Extension API Specification & Reference for
information about standard algorithm names.provider
- the providerpublic final Provider getProvider()
public final void init(Key key) throws InvalidKeyException
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.public final void init(Key key, SecureRandom random) throws InvalidKeyException
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.
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 randomnesspublic final void init(Key key, AlgorithmParameterSpec params) throws InvalidKeyException, InvalidAlgorithmParameterException
If this key agreement requires any random bytes, a system-provided source of randomness is used.
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 parameterspublic final void init(Key key, AlgorithmParameterSpec params, SecureRandom random) throws InvalidKeyException, InvalidAlgorithmParameterException
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 parametersrandom
- the source of randomnesspublic final Key doPhase(Key key, boolean lastPhase) throws InvalidKeyException, IllegalStateException
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.public final byte[] generateSecret() throws IllegalStateException
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 engineInit methods, the same private information and algorithm parameters will be used for subsequent key agreements.
public final int generateSecret(byte[] sharedSecret, int offset) throws IllegalStateException, ShortBufferException
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 engineInit methods, the same private information and algorithm parameters will be used for subsequent key agreements.
sharedSecret
- the buffer for the shared secretoffset
- the offset in sharedSecret where the shared
secret will be storedpublic final SecretKey generateSecret(String algorithm) throws IllegalStateException, NoSuchAlgorithmException, InvalidKeyException
This method resets this KeyAgreementSpi object, so that it can be reused for further key agreements. Unless this key agreement is reinitialized with one of the engineInit methods, the same private information and algorithm parameters will be used for subsequent key agreements.
algorithm
- the requested secret key algorithm
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