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java.lang.Object | +----javax.crypto.KeyAgreementSpi
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.
Constructor Summary | |
KeyAgreementSpi()
|
Method Summary | |
java.security.Key | engineDoPhase(java.security.Key key,
boolean lastPhase)
|
byte[] | engineGenerateSecret()
|
int | engineGenerateSecret(byte[] sharedSecret,
int offset)
sharedSecret , beginning at offset .
|
SecretKey | engineGenerateSecret(java.lang.String algorithm)
|
void | engineInit(java.security.Key key,
java.security.SecureRandom random)
|
void | engineInit(java.security.Key key,
java.security.spec.AlgorithmParameterSpec params,
java.security.SecureRandom random)
|
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 parameters
random
- the source of randomness
protected 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
reinitialized 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
sharedSecret
, beginning at offset
.
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.
sharedSecret
- the buffer for the shared secret
offset
- the offset in sharedSecret
where the
shared secret will be stored
sharedSecret
protected 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
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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