javax.crypto

## Class SecretKeyFactorySpi

- java.lang.Object
- - javax.crypto.SecretKeyFactorySpi

-     public abstract class SecretKeyFactorySpi
      extends Object

  This class defines the Service Provider Interface (SPI) for the `SecretKeyFactory` class. All the abstract methods in this class must be implemented by each cryptographic service provider who wishes to supply the implementation of a secret-key factory for a particular algorithm.

  A provider should document all the key specifications supported by its secret key factory. 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`

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `SecretKeyFactorySpi()`

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `protected abstract SecretKey` | `engineGenerateSecret(KeySpec keySpec)` Generates a `SecretKey` object from the provided key specification (key material).
    `protected abstract KeySpec` | `engineGetKeySpec(SecretKey key, Class keySpec)` Returns a specification (key material) of the given key object in the requested format.
    `protected abstract SecretKey` | `engineTranslateKey(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

    - #### SecretKeyFactorySpi

          public SecretKeyFactorySpi()

  - ### Method Detail

    - #### engineGenerateSecret

          protected abstract SecretKey engineGenerateSecret(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.

    - #### engineGetKeySpec

          protected abstract KeySpec engineGetKeySpec(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).

    - #### engineTranslateKey

          protected abstract SecretKey engineTranslateKey(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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