java.security
Class KeyFactory

java.lang.Object
  |
  +--java.security.KeyFactory

public class KeyFactory

extends Object

Safe: 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.

The following is an example of how to use a key factory in order to instantiate a DSA public key from its encoding. Assume Alice has received a digital signature from Bob. Bob also sent her his public key (in encoded format) to verify his signature. Alice then performs the following actions:

 X509EncodedKeySpec bobPubKeySpec = new X509EncodedKeySpec(bobEncodedPubKey);
 KeyFactory keyFactory = KeyFactory.getInstance("DSA");
 PublicKey bobPubKey = keyFactory.generatePublic(bobPubKeySpec);
 Signature sig = Signature.getInstance("DSA");
 sig.initVerify(bobPubKey);
 sig.update(data);
 sig.verify(signature);
 

Since:

1.2

Version:

1.28, 05/07/02

Author:

Jan Luehe

See Also:

Key, PublicKey, PrivateKey, java.security.spec.KeySpec, java.security.spec.DSAPublicKeySpec, java.security.spec.X509EncodedKeySpec

Field Summary

private String	algorithm
private KeyFactorySpi	keyFacSpi
private Provider	provider

Constructor Summary

protected

KeyFactory(KeyFactorySpi keyFacSpi, Provider provider, String algorithm) Creates a KeyFactory object.

Method Summary

Object[]	__optUncall() Added:
PrivateKey	generatePrivate(KeySpec keySpec) Enabled: Generates a private key object from the provided key specification (key material).
PublicKey	generatePublic(KeySpec keySpec) Enabled: Generates a public key object from the provided key specification (key material).
String	getAlgorithm() Enabled: Gets the name of the algorithm associated with this KeyFactory.
static KeyFactory	getInstance(String algorithm) Enabled: Generates a KeyFactory object that implements the specified algorithm.
static KeyFactory	getInstance(String algorithm, Provider provider) Enabled: Generates a KeyFactory object for the specified algorithm from the specified provider.
static KeyFactory	getInstance(String algorithm, String provider) Enabled: Generates a KeyFactory object for the specified algorithm from the specified provider.
KeySpec	getKeySpec(Key key, Class keySpec) Enabled: Returns a specification (key material) of the given key object.
Provider	getProvider() Enabled: Returns the provider of this key factory object.
Key	translateKey(Key key) Enabled: Translates a key object, whose provider may be unknown or potentially untrusted, into a corresponding key object of this key factory.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

algorithm

private String algorithm

provider

private Provider provider

keyFacSpi

private KeyFactorySpi keyFacSpi

Constructor Detail

KeyFactory

protected KeyFactory(KeyFactorySpi keyFacSpi,
                     Provider provider,
                     String algorithm)

Creates a KeyFactory object.

Parameters:

keyFacSpi - the delegate

provider - the provider

algorithm - the name of the algorithm to associate with this KeyFactory

Method Detail

getInstance

public static KeyFactory getInstance(String algorithm)
                              throws NoSuchAlgorithmException

Enabled: Generates a KeyFactory object that implements the specified algorithm. If the default provider package provides an implementation of the requested algorithm, an instance of KeyFactory containing that implementation is returned. If the algorithm is not available in the default package, other packages are searched.

Parameters:

algorithm - the name of the requested key algorithm. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard algorithm names.

Returns:

a KeyFactory object for the specified algorithm.

NoSuchAlgorithmException

getInstance

public static KeyFactory getInstance(String algorithm,
                                     String provider)
                              throws NoSuchAlgorithmException,
                                     NoSuchProviderException

Enabled: Generates a KeyFactory object for the specified algorithm from the specified provider.

Parameters:

algorithm - the name of the requested key algorithm. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard algorithm names.

provider - the name of the provider.

Returns:

a KeyFactory object for the specified algorithm.

NoSuchAlgorithmException

NoSuchProviderException

See Also:

Provider

getInstance

public static KeyFactory getInstance(String algorithm,
                                     Provider provider)
                              throws NoSuchAlgorithmException

Enabled: Generates a KeyFactory object for the specified algorithm from the specified provider. Note: the provider doesn't have to be registered.

Parameters:

algorithm - the name of the requested key algorithm. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard algorithm names.

provider - the provider.

Returns:

a KeyFactory object for the specified algorithm.

NoSuchAlgorithmException

Since:

1.4

See Also:

Provider

getProvider

public final Provider getProvider()

Enabled: Returns the provider of this key factory object.

Returns:

the provider of this key factory object

getAlgorithm

public final String getAlgorithm()

Enabled: Gets the name of the algorithm associated with this KeyFactory.

Returns:

the name of the algorithm associated with this KeyFactory

generatePublic

public final PublicKey generatePublic(KeySpec keySpec)
                               throws InvalidKeySpecException

Enabled: 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.

InvalidKeySpecException

generatePrivate

public final PrivateKey generatePrivate(KeySpec keySpec)
                                 throws InvalidKeySpecException

Enabled: 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.

InvalidKeySpecException

getKeySpec

public final KeySpec getKeySpec(Key key,
                                Class keySpec)
                         throws InvalidKeySpecException

Enabled: 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.

InvalidKeySpecException

translateKey

public final Key translateKey(Key key)
                       throws InvalidKeyException

Enabled: 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.

InvalidKeyException

__optUncall

public Object[] __optUncall()

Added:

Returns: