public class SecretKeyFactory 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), 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:
 
SecretKey, 
DESKeySpec, 
DESedeKeySpec, 
PBEKeySpec| Modifier | Constructor and Description | 
|---|---|
| protected  | SecretKeyFactory(SecretKeyFactorySpi keyFacSpi,
                Provider provider,
                String algorithm)Creates a SecretKeyFactory object. | 
| Modifier and Type | Method and Description | 
|---|---|
| SecretKey | generateSecret(KeySpec keySpec)Generates a  SecretKeyobject from the provided key
 specification (key material). | 
| String | getAlgorithm()Returns the algorithm name of this  SecretKeyFactoryobject. | 
| static SecretKeyFactory | getInstance(String algorithm)Returns a  SecretKeyFactoryobject that converts
 secret keys of the specified algorithm. | 
| static SecretKeyFactory | getInstance(String algorithm,
           Provider provider)Returns a  SecretKeyFactoryobject that converts
 secret keys of the specified algorithm. | 
| static SecretKeyFactory | getInstance(String algorithm,
           String provider)Returns a  SecretKeyFactoryobject that converts
 secret keys of the specified algorithm. | 
| KeySpec | getKeySpec(SecretKey key,
          Class<?> keySpec)Returns a specification (key material) of the given key object
 in the requested format. | 
| Provider | getProvider()Returns the provider of this  SecretKeyFactoryobject. | 
| SecretKey | translateKey(SecretKey key)Translates a key object, whose provider may be unknown or potentially
 untrusted, into a corresponding key object of this secret-key factory. | 
protected SecretKeyFactory(SecretKeyFactorySpi keyFacSpi, Provider provider, String algorithm)
keyFacSpi - the delegateprovider - the provideralgorithm - the secret-key algorithmpublic static final SecretKeyFactory getInstance(String algorithm) throws NoSuchAlgorithmException
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.Providerpublic static final SecretKeyFactory getInstance(String algorithm, String provider) throws NoSuchAlgorithmException, NoSuchProviderException
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.Providerpublic static final SecretKeyFactory getInstance(String algorithm, Provider provider) throws NoSuchAlgorithmException
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.Providerpublic final Provider getProvider()
SecretKeyFactory object.SecretKeyFactory objectpublic final String getAlgorithm()
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
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
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
key - the key whose provider is unknown or untrustedInvalidKeyException - if the given key cannot be processed
 by this secret-key factory. Submit a bug or feature 
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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