Class KeyFactorySpi
java.lang.Object
java.security.KeyFactorySpi
This class defines the Service Provider Interface (SPI)
for the
KeyFactory
class.
All the abstract methods in this class must be implemented by each
cryptographic service provider who wishes to supply the implementation
of a key factory for a particular algorithm.
Key factories are used to convert keys (opaque
cryptographic keys of type Key
) into key specifications
(transparent representations of the underlying key material), and vice
versa.
Key factories are bidirectional. That is, they allow you to build an opaque key object from a given key specification (key material), or to retrieve the underlying key material of a key object in a suitable format.
Multiple compatible key specifications may exist for the same key.
For example, a DSA public key may be specified using
DSAPublicKeySpec
or
X509EncodedKeySpec
. A key factory can be used to translate
between compatible key specifications.
A provider should document all the key specifications supported by its key factory.
- Since:
- 1.2
- See Also:
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Constructor Summary
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Method Summary
Modifier and TypeMethodDescriptionprotected abstract PrivateKey
engineGeneratePrivate
(KeySpec keySpec) Generates a private key object from the provided key specification (key material).protected abstract PublicKey
engineGeneratePublic
(KeySpec keySpec) Generates a public key object from the provided key specification (key material).protected abstract <T extends KeySpec>
TengineGetKeySpec
(Key key, Class<T> keySpec) Returns a specification (key material) of the given key object.protected abstract Key
engineTranslateKey
(Key key) Translates a key object, whose provider may be unknown or potentially untrusted, into a corresponding key object of this key factory.
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Constructor Details
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KeyFactorySpi
public KeyFactorySpi()Constructor for subclasses to call.
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Method Details
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engineGeneratePublic
Generates a public key object from the provided key specification (key material).- Parameters:
keySpec
- the specification (key material) of the public key.- Returns:
- the public key.
- Throws:
InvalidKeySpecException
- if the given key specification is inappropriate for this key factory to produce a public key.
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engineGeneratePrivate
Generates a private key object from the provided key specification (key material).- Parameters:
keySpec
- the specification (key material) of the private key.- Returns:
- the private key.
- Throws:
InvalidKeySpecException
- if the given key specification is inappropriate for this key factory to produce a private key.
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engineGetKeySpec
protected abstract <T extends KeySpec> T engineGetKeySpec(Key key, Class<T> keySpec) throws InvalidKeySpecException Returns a specification (key material) of the given key object.keySpec
identifies the specification class in which the key material should be returned. It could, for example, beDSAPublicKeySpec.class
, to indicate that the key material should be returned in an instance of theDSAPublicKeySpec
class.- Type Parameters:
T
- the type of the key specification to be returned- Parameters:
key
- the key.keySpec
- the specification class in which the key material should be returned.- Returns:
- the underlying key specification (key material) in an instance of the requested specification class.
- Throws:
InvalidKeySpecException
- if the requested key specification is inappropriate for the given key, or the given key cannot be dealt with (e.g., the given key has an unrecognized format).
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engineTranslateKey
Translates a key object, whose provider may be unknown or potentially untrusted, into a corresponding key object of this key factory.- Parameters:
key
- the key whose provider is unknown or untrusted.- Returns:
- the translated key.
- Throws:
InvalidKeyException
- if the given key cannot be processed by this key factory.
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