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javax.crypto
abstract public class: KeyAgreementSpi [javadoc | source]
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 ( 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.

Method from javax.crypto.KeyAgreementSpi Summary:
engineDoPhase,   engineGenerateSecret,   engineGenerateSecret,   engineGenerateSecret,   engineInit,   engineInit
Methods from java.lang.Object:
clone,   equals,   finalize,   getClass,   hashCode,   notify,   notifyAll,   toString,   wait,   wait,   wait
Method from javax.crypto.KeyAgreementSpi Detail:
 abstract protected Key engineDoPhase(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.
 abstract protected byte[] engineGenerateSecret() throws IllegalStateException
    Generates the shared secret and returns it in a new buffer.

    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.

 abstract protected SecretKey engineGenerateSecret(String algorithm) throws IllegalStateException, NoSuchAlgorithmException, InvalidKeyException
    Creates the shared secret and returns it as a secret key object of the requested algorithm type.

    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.

 abstract protected int engineGenerateSecret(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 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.

 abstract protected  void engineInit(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.

 abstract protected  void engineInit(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.