public class SecretKeyFactory extends Object
This class represents a factory for secret keys.
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. Secret key factories operate only on secret (symmetric) keys.
Key factories are bi-directional, i.e., they allow 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.
Application developers should refer to their provider's documentation to find out which key specifications are supported by the generateSecret
and getKeySpec
methods. For example, the DES secret-key factory supplied by the "SunJCE" provider supports DESKeySpec
as a transparent representation of DES keys, and that provider's secret-key factory for Triple DES keys supports DESedeKeySpec
as a transparent representation of Triple DES keys.
Every implementation of the Java platform is required to support the following standard SecretKeyFactory
algorithms:
DES
DESede
SecretKey
, DESKeySpec
, DESedeKeySpec
, PBEKeySpec
protected SecretKeyFactory(SecretKeyFactorySpi keyFacSpi, Provider provider, String algorithm)
Creates a SecretKeyFactory object.
keyFacSpi
- the delegateprovider
- the provideralgorithm
- the secret-key algorithmpublic static final SecretKeyFactory getInstance(String algorithm) throws NoSuchAlgorithmException
Returns a SecretKeyFactory
object that converts secret keys of the specified algorithm.
This method traverses the list of registered security Providers, starting with the most preferred Provider. A new SecretKeyFactory object encapsulating the SecretKeyFactorySpi implementation from the first Provider that supports the specified algorithm is returned.
Note that the list of registered providers may be retrieved via the Security.getProviders()
method.
algorithm
- the standard name of the requested secret-key algorithm. See the SecretKeyFactory section in the Java Cryptography Architecture Standard Algorithm Name Documentation for information about standard algorithm names.SecretKeyFactory
object.NullPointerException
- if the specified algorithm is null.NoSuchAlgorithmException
- if no Provider supports a SecretKeyFactorySpi implementation for the specified algorithm.Provider
public static final SecretKeyFactory getInstance(String algorithm, String provider) throws NoSuchAlgorithmException, NoSuchProviderException
Returns a SecretKeyFactory
object that converts secret keys of the specified algorithm.
A new SecretKeyFactory object encapsulating the SecretKeyFactorySpi implementation from the specified provider is returned. The specified provider must be registered in the security provider list.
Note that the list of registered providers may be retrieved via the Security.getProviders()
method.
algorithm
- the standard name of the requested secret-key algorithm. See the SecretKeyFactory section in the Java Cryptography Architecture Standard Algorithm Name Documentation for information about standard algorithm names.provider
- the name of the provider.SecretKeyFactory
object.NoSuchAlgorithmException
- if a SecretKeyFactorySpi implementation for the specified algorithm is not available from the specified provider.NullPointerException
- if the specified algorithm is null.NoSuchProviderException
- if the specified provider is not registered in the security provider list.IllegalArgumentException
- if the provider
is null or empty.Provider
public static final SecretKeyFactory getInstance(String algorithm, Provider provider) throws NoSuchAlgorithmException
Returns a SecretKeyFactory
object that converts secret keys of the specified algorithm.
A new SecretKeyFactory object encapsulating the SecretKeyFactorySpi implementation from the specified Provider object is returned. Note that the specified Provider object does not have to be registered in the provider list.
algorithm
- the standard name of the requested secret-key algorithm. See the SecretKeyFactory section in the Java Cryptography Architecture Standard Algorithm Name Documentation for information about standard algorithm names.provider
- the provider.SecretKeyFactory
object.NullPointerException
- if the specified algorithm is null.NoSuchAlgorithmException
- if a SecretKeyFactorySpi implementation for the specified algorithm is not available from the specified Provider object.IllegalArgumentException
- if the provider
is null.Provider
public final Provider getProvider()
Returns the provider of this SecretKeyFactory
object.
SecretKeyFactory
objectpublic final String getAlgorithm()
Returns the algorithm name of this SecretKeyFactory
object.
This is the same name that was specified in one of the getInstance
calls that created this SecretKeyFactory
object.
SecretKeyFactory
object.public final SecretKey generateSecret(KeySpec keySpec) throws InvalidKeySpecException
Generates a SecretKey
object from the provided key specification (key material).
keySpec
- the specification (key material) of the secret keyInvalidKeySpecException
- if the given key specification is inappropriate for this secret-key factory to produce a secret key.public final KeySpec getKeySpec(SecretKey key, Class<?> keySpec) throws InvalidKeySpecException
Returns a specification (key material) of the given key object in the requested format.
key
- the keykeySpec
- the requested format in which the key material shall be returnedInvalidKeySpecException
- if the requested key specification is inappropriate for the given key (e.g., the algorithms associated with key
and keySpec
do not match, or key
references a key on a cryptographic hardware device whereas keySpec
is the specification of a software-based key), or the given key cannot be dealt with (e.g., the given key has an algorithm or format not supported by this secret-key factory).public final SecretKey translateKey(SecretKey key) throws InvalidKeyException
Translates a key object, whose provider may be unknown or potentially untrusted, into a corresponding key object of this secret-key factory.
key
- the key whose provider is unknown or untrustedInvalidKeyException
- if the given key cannot be processed by this secret-key factory.
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