javax.crypto
Class KeyAgreementSpi
- java.lang.Object
javax.crypto.KeyAgreementSpi
- public abstract class KeyAgreementSpi
- extends java.lang.Object
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.
Constructor Summary
Constructor and Description |
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KeyAgreementSpi()
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Method Summary
Modifier and Type | Method and Description |
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|
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.
|
|
engineGenerateSecret()
Generates the shared secret and returns it in a new buffer.
|
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engineGenerateSecret(byte[] sharedSecret,int offset)
Generates the shared secret, and places it into the buffer
sharedSecret , beginning at offset inclusive.
|
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engineGenerateSecret(java.lang.String algorithm)
Creates the shared secret and returns it as a secret key object
of the requested algorithm type.
|
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engineInit(java.security.Key key,java.security.spec.AlgorithmParameterSpec params,java.security.SecureRandom random)
Initializes this key agreement with the given key, set of
algorithm parameters, and source of randomness.
|
|
engineInit(java.security.Key key,java.security.SecureRandom random)
Initializes this key agreement with the given key and source of
randomness.
|
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail
KeyAgreementSpi
- public KeyAgreementSpi()
Method Detail
engineInit
- protected abstract void engineInit( java.security.Key key,
- java.security.SecureRandom random)
- throws java.security.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. random
- the source of randomness java.security.InvalidKeyException
- if the given key is
inappropriate for this key agreement, e.g., is of the wrong type or
has an incompatible algorithm type. engineInit
- 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 java.security.InvalidKeyException
- if the given key is
inappropriate for this key agreement, e.g., is of the wrong type or
has an incompatible algorithm type. java.security.InvalidAlgorithmParameterException
- if the given parameters
are inappropriate for this key agreement. engineDoPhase
- 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. java.security.InvalidKeyException
- if the given key is inappropriate for
this phase. java.lang.IllegalStateException
- if this key agreement has not been
initialized. engineGenerateSecret
- 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.
java.lang.IllegalStateException
- if this key agreement has not been
completed yet engineGenerateSecret
- protected abstract int engineGenerateSecret( byte[] sharedSecret,
- int offset)
- throws java.lang.IllegalStateException
- ShortBufferException
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.
sharedSecret
- the buffer for the shared secret offset
- the offset in sharedSecret
where the
shared secret will be stored sharedSecret
java.lang.IllegalStateException
- if this key agreement has not been
completed yet ShortBufferException
- if the given output buffer is too small
to hold the secret engineGenerateSecret
- 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 java.lang.IllegalStateException
- if this key agreement has not been
completed yet java.security.NoSuchAlgorithmException
- if the requested secret key
algorithm is not available java.security.InvalidKeyException
- if the shared secret key material cannot
be used to generate a secret key of the requested algorithm type (e.g.,
the key material is too short)
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.