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## javax.crypto
Class SecretKeyFactory

    java.lang.Object
      javax.crypto.SecretKeyFactory

    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.

Since:
  1.4
See Also:
  `SecretKey`, `DESKeySpec`, `DESedeKeySpec`, `PBEKeySpec`

Constructor Summary
`protected` | `SecretKeyFactory(SecretKeyFactorySpi keyFacSpi, Provider provider, String algorithm)` Creates a SecretKeyFactory object.

Method Summary
`SecretKey` | `generateSecret(KeySpec keySpec)` Generates a `SecretKey` object from the provided key specification (key material).
`String` | `getAlgorithm()` Returns the algorithm name of this `SecretKeyFactory` object.
`static SecretKeyFactory` | `getInstance(String algorithm)` Generates a `SecretKeyFactory` object for the specified secret-key algorithm.
`static SecretKeyFactory` | `getInstance(String algorithm, Provider provider)` Generates a `SecretKeyFactory` object for the specified secret-key algorithm from the specified provider.
`static SecretKeyFactory` | `getInstance(String algorithm, String provider)` Generates a `SecretKeyFactory` object for the specified secret-key algorithm from the specified provider.
`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 `SecretKeyFactory` object.
`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.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### SecretKeyFactory

    protected SecretKeyFactory(SecretKeyFactorySpi keyFacSpi,
                               Provider provider,
                               String algorithm)

  Creates a SecretKeyFactory object.

  Parameters:
    `keyFacSpi` - the delegate
    `provider` - the provider
    `algorithm` - the secret-key algorithm

Method Detail

### getInstance

    public static final SecretKeyFactory getInstance(String algorithm)
                                              throws NoSuchAlgorithmException

  Generates a `SecretKeyFactory` object for the specified secret-key algorithm. If the default provider package provides an implementation of the requested factory, an instance of `SecretKeyFactory` containing that implementation is returned. If the requested factory is not available in the default provider package, other provider packages are searched.

  Parameters:
    `algorithm` - the standard name of the requested secret-key algorithm. See Appendix A in the Java Cryptography Extension Reference Guide for information about standard algorithm names.
  Returns:
    a `SecretKeyFactory` object for the specified secret-key algorithm.
  Throws:
    `NullPointerException` - if the specified algorithm is null.
    `NoSuchAlgorithmException` - if a secret-key factory for the specified algorithm is not available in the default provider package or any of the other provider packages that were searched.

### getInstance

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

  Generates a `SecretKeyFactory` object for the specified secret-key algorithm from the specified provider.

  Parameters:
    `algorithm` - the standard name of the requested secret-key algorithm. See Appendix A in the Java Cryptography Extension Reference Guide for information about standard algorithm names.
    `provider` - the name of the provider.
  Returns:
    a `SecretKeyFactory` object for the specified secret-key algorithm.
  Throws:
    `NoSuchAlgorithmException` - if a secret-key factory for the specified algorithm is not available from the specified provider.
    `NullPointerException` - if the specified algorithm is null.
    `NoSuchProviderException` - if the specified provider has not been configured.
    `IllegalArgumentException` - if the `provider` is null.

### getInstance

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

  Generates a `SecretKeyFactory` object for the specified secret-key algorithm from the specified provider. Note: the `provider` doesn't have to be registered.

  Parameters:
    `algorithm` - the standard name of the requested secret-key algorithm. See Appendix A in the Java Cryptography Extension Reference Guide for information about standard algorithm names.
    `provider` - the provider.
  Returns:
    a `SecretKeyFactory` object for the specified secret-key algorithm.
  Throws:
    `NullPointerException` - if the specified algorithm is null.
    `NoSuchAlgorithmException` - if a secret-key factory for the specified algorithm is not available from the specified provider.
    `IllegalArgumentException` - if the `provider` is null.

### getProvider

    public final Provider getProvider()

  Returns the provider of this `SecretKeyFactory` object.

  Returns:
    the provider of this `SecretKeyFactory` object

### getAlgorithm

    public 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.

  Returns:
    the algorithm name of this `SecretKeyFactory` object.

### generateSecret

    public final SecretKey generateSecret(KeySpec keySpec)
                                   throws InvalidKeySpecException

  Generates a `SecretKey` object from the provided key specification (key material).

  Parameters:
    `keySpec` - the specification (key material) of the secret key
  Returns:
    the secret key
  Throws:
    `InvalidKeySpecException` - if the given key specification is inappropriate for this secret-key factory to produce a secret key.

### getKeySpec

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

  Returns a specification (key material) of the given key object in the requested format.

  Parameters:
    `key` - the key
    `keySpec` - the requested format in which the key material shall be returned
  Returns:
    the underlying key specification (key material) in the requested format
  Throws:
    `InvalidKeySpecException` - 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).

### translateKey

    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.

  Parameters:
    `key` - the key whose provider is unknown or untrusted
  Returns:
    the translated key
  Throws:
    `InvalidKeyException` - if the given key cannot be processed by this secret-key factory.

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For further API reference and developer documentation, see Java 2 SDK SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

Copyright 2004 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.