java.security

Class KeyFactory

public class KeyFactory extends Object

Key factories are used to convert keys (opaque cryptographic keys of type {@link 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

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

Method Summary
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, String provider) Returns a new instance of `KeyFactory` representing the specified key factory from the specified provider.
static KeyFactory	getInstance(String algorithm, Provider provider) Returns a new instance of `KeyFactory` representing the specified key factory from the designated {@link Provider}.
<T extends KeySpec> T	getKeySpec(Key key, Class<T> keySpec) Returns a key specification for the given key.
Provider	getProvider() Returns the {@link Provider} of this instance.
Key	translateKey(Key key) Translates the key from an unknown or untrusted provider into a key from this key factory.

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

generatePrivate

public final PrivateKey generatePrivate(KeySpec keySpec)

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.

generatePublic

public final PublicKey generatePublic(KeySpec keySpec)

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.

getAlgorithm

public final String getAlgorithm()

Returns the name of the algorithm used.

Returns: the name of the algorithm used.

getInstance

public static KeyFactory getInstance(String algorithm)

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)

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)

Returns a new instance of KeyFactory representing the specified key factory from the designated {@link Provider}.

Parameters: algorithm the name of algorithm to use. provider the {@link Provider} to use.

Returns: a new instance repesenting the desired algorithm.

Throws: NoSuchAlgorithmException if the algorithm is not implemented by {@link Provider}. IllegalArgumentException if either algorithm or provider is null, or if algorithm is an empty string.

Since: 1.4

getKeySpec

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

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.

getProvider

public final Provider getProvider()

Returns the {@link Provider} of this instance.

Returns: the {@link Provider} of this instance.

translateKey

public final Key translateKey(Key key)

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.