java.security

Class KeyFactory

java.lang.Object

java.security.KeyFactory

public class KeyFactory
extends Object

Key factories are used to convert keys (opaque cryptographic keys of type Key) into key specifications (transparent representations of the underlying key material).

Key factories are bi-directional. They allow a key class to be converted into a key specification (key material) and back again. For example DSA public keys can be specified as DSAPublicKeySpec or X509EncodedKeySpec. A key factory translates these key specifications.

Since:

1.2

See Also:

Key, KeySpec, DSAPublicKeySpec, X509EncodedKeySpec

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	KeyFactory(KeyFactorySpi keyFacSpi, Provider provider, String algorithm) Constructs a new instance of KeyFactory with the specified parameters.

Method Summary

Methods

Modifier and Type	Method and Description
PrivateKey	generatePrivate(KeySpec keySpec) Generates a private key from the provided key specification.
PublicKey	generatePublic(KeySpec keySpec) Generates a public key from the provided key specification.
String	getAlgorithm() Returns the name of the algorithm used.
static KeyFactory	getInstance(String algorithm) Returns a new instance of KeyFactory representing the specified key factory.
static KeyFactory	getInstance(String algorithm, Provider provider) Returns a new instance of KeyFactory representing the specified key factory from the designated Provider.
static KeyFactory	getInstance(String algorithm, String provider) Returns a new instance of KeyFactory representing the specified key factory from the specified provider.
<T extends KeySpec> T	getKeySpec(Key key, Class<T> keySpec) Returns a key specification for the given key.
Provider	getProvider() Returns the Provider of this instance.
Key	translateKey(Key key) Translates the key from an unknown or untrusted provider into a key from this key factory.

Methods inherited from class java.lang.Object

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

Constructor Detail

KeyFactory

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

Constructs a new instance of KeyFactory with the specified parameters.

Parameters:

keyFacSpi - the key factory to use.

provider - the provider to use.

algorithm - the name of the key algorithm to use.

Method Detail

getInstance

public static KeyFactory getInstance(String algorithm)
                              throws NoSuchAlgorithmException

Returns a new instance of KeyFactory representing the specified key factory.

Parameters:

algorithm - the name of algorithm to use.

Returns:

a new instance repesenting the desired algorithm.

Throws:

NoSuchAlgorithmException - if the algorithm is not implemented by any provider.

IllegalArgumentException - if algorithm is null or is an empty string.

getInstance

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

Returns a new instance of KeyFactory representing the specified key factory from the specified provider.

Parameters:

algorithm - the name of algorithm to use.

provider - the name of the provider to use.

Returns:

a new instance repesenting the desired algorithm.

Throws:

NoSuchAlgorithmException - if the algorithm is not implemented by the named provider.

NoSuchProviderException - if the named provider was not found.

IllegalArgumentException - if either algorithm or provider is null or empty.

getInstance

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

Returns a new instance of KeyFactory representing the specified key factory from the designated Provider.

Parameters:

algorithm - the name of algorithm to use.

provider - the Provider to use.

Returns:

a new instance repesenting the desired algorithm.

Throws:

NoSuchAlgorithmException - if the algorithm is not implemented by Provider.

IllegalArgumentException - if either algorithm or provider is null, or if algorithm is an empty string.

Since:

1.4

See Also:

Provider

getProvider

public final Provider getProvider()

Returns the Provider of this instance.

Returns:

the Provider of this instance.

getAlgorithm

public final String getAlgorithm()

Returns the name of the algorithm used.

Returns:

the name of the algorithm used.

generatePublic

public final PublicKey generatePublic(KeySpec keySpec)
                               throws InvalidKeySpecException

Generates a public key from the provided key specification.

Parameters:

keySpec - the key specification.

Returns:

the public key.

Throws:

InvalidKeySpecException - if the key specification is invalid.

generatePrivate

public final PrivateKey generatePrivate(KeySpec keySpec)
                                 throws InvalidKeySpecException

Generates a private key from the provided key specification.

Parameters:

keySpec - the key specification.

Returns:

the private key.

Throws:

InvalidKeySpecException - if the key specification is invalid.

getKeySpec

public final <T extends KeySpec> T getKeySpec(Key key,
                               Class<T> keySpec)
                                   throws InvalidKeySpecException

Returns a key specification for the given key. keySpec identifies the specification class to return the key material in.

Parameters:

key - the key to use.

keySpec - the specification class to use.

Returns:

the key specification in an instance of the requested specification class.

Throws:

InvalidKeySpecException - the requested key specification is inappropriate for this key or the key is unrecognized.

translateKey

public final Key translateKey(Key key)
                       throws InvalidKeyException

Translates the key from an unknown or untrusted provider into a key from this key factory.

Parameters:

key - the key to translate from.

Returns:

the translated key.

Throws:

InvalidKeyException - if the key cannot be processed by this key factory.