KeyFactorySpi

AI-generated Key Takeaways

• KeyFactorySpi is a Service Provider Interface (SPI) for the KeyFactory class, enabling cryptographic providers to implement key factory functionalities for specific algorithms.

• Key factories are used to convert between opaque Key objects and transparent KeySpec objects, allowing bidirectional transformation between keys and their underlying specifications.

• They support translating keys between compatible key specifications, such as converting a DSA public key from DSAPublicKeySpec to X509EncodedKeySpec.

• Implementations of KeyFactorySpi must provide methods for generating public/private keys from key specifications, retrieving key specifications from key objects, and translating keys between providers.

public abstract class KeyFactorySpi extends Object

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 bi-directional. 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.

See Also

• KeyFactory
• Key
• PublicKey
• PrivateKey
• KeySpec
• DSAPublicKeySpec
• X509EncodedKeySpec

Public Constructor Summary

KeyFactorySpi()

Protected Method Summary

abstract PrivateKey	engineGeneratePrivate(KeySpec keySpec) Generates a private key object from the provided key specification (key material).
abstract PublicKey	engineGeneratePublic(KeySpec keySpec) Generates a public key object from the provided key specification (key material).
abstract <T extends KeySpec> T	engineGetKeySpec(Key key, Class<T> keySpec) Returns a specification (key material) of the given key object.
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.

Inherited Method Summary

From class java.lang.Object

Object	clone() Creates and returns a copy of this Object.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of Class that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object.

Public Constructors

public KeyFactorySpi ()

Protected Methods

protected abstract PrivateKey engineGeneratePrivate (KeySpec keySpec)

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.

protected abstract PublicKey engineGeneratePublic (KeySpec keySpec)

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.

protected abstract T engineGetKeySpec (Key key, Class<T> keySpec)

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, be DSAPublicKeySpec.class, to indicate that the key material should be returned in an instance of the DSAPublicKeySpec class.

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).

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.

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.