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java.lang.Object | +--javax.crypto.KeyAgreementSpi
This class defines the Service Provider Interface (SPI) for the KeyAgreement class. All the abstract methods in this class must be implemented by each cryptographic service provider who wishes to supply the implementation of a particular key agreement algorithm.
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 engineDoPhase).
For each of the correspondents in the key exchange, engineDoPhase needs to be called. For example, if the key exchange is with one other party, engineDoPhase needs to be called once, with the lastPhase flag set to true. If the key exchange is with two other parties, engineDoPhase 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.
KeyGenerator
,
SecretKey
Constructor Summary | |
KeyAgreementSpi()
Default constructor for KeyAgreementSpi, must be public. |
Method Summary | |
protected abstract java.security.Key |
engineDoPhase(java.security.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. |
protected abstract byte[] |
engineGenerateSecret()
Generates the shared secret and returns it in a new buffer. |
protected abstract int |
engineGenerateSecret(byte[] sharedSecret,
int offset)
Generates the shared secret, and places it into the buffer sharedSecret, beginning at offset. |
protected abstract SecretKey |
engineGenerateSecret(java.lang.String algorithm)
Creates the shared secret and returns it as a secret key object of the requested algorithm type. |
protected abstract void |
engineInit(java.security.Key key,
java.security.spec.AlgorithmParameterSpec params,
java.security.SecureRandom random)
Initialises this key agreement with the given key, set of algorithm parameters, and source of randomness. |
protected abstract void |
engineInit(java.security.Key key,
java.security.SecureRandom random)
Initialises 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 |
public KeyAgreementSpi()
Method Detail |
protected abstract void engineInit(java.security.Key key, java.security.SecureRandom random) throws java.security.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 randomness.protected abstract void engineInit(java.security.Key key, java.security.spec.AlgorithmParameterSpec params, java.security.SecureRandom random) throws java.security.InvalidKeyException, java.security.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 randomnessprotected abstract java.security.Key engineDoPhase(java.security.Key key, boolean lastPhase) throws java.security.InvalidKeyException, java.lang.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.protected abstract byte[] engineGenerateSecret() throws java.lang.IllegalStateException
This method resets this KeyAgreementSpi object, so that it can be reused for further key agreements. Unless this key agreement is reinitialised with one of the engineInit methods, the same private information and algorithm parameters will be used for subsequent key agreements.
protected abstract int engineGenerateSecret(byte[] sharedSecret, int offset) throws java.lang.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 KeyAgreementSpi object, so that it can be reused for further key agreements. Unless this key agreement is reinitialised 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 storedprotected abstract SecretKey engineGenerateSecret(java.lang.String algorithm) throws java.lang.IllegalStateException, java.security.NoSuchAlgorithmException, java.security.InvalidKeyException
This method resets this KeyAgreementSpi object, so that it can be reused for further key agreements. Unless this key agreement is reinitialised 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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