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 bidirectional, 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 DESede (Triple DES) secret key factory supplied by the "SunJCE" provider 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:

  • PBEWithHmacSHA256AndAES_128
  • PBEWithHmacSHA256AndAES_256
  • PBKDF2WithHmacSHA256
These algorithms are described in the SecretKeyFactory section of the Java Security Standard Algorithm Names Specification. Consult the release documentation for your implementation to see if any other algorithms are supported.
Since:
1.4
External Specifications
See Also:

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    protected
    SecretKeyFactory(SecretKeyFactorySpi keyFacSpi, Provider provider, String algorithm)
    Creates a SecretKeyFactory object.

  • Method Summary

    Modifier and Type
    Method
    Description
    final SecretKey
    generateSecret(KeySpec keySpec)
    Generates a SecretKey object from the provided key specification (key material).
    final String
    getAlgorithm()
    Returns the algorithm name of this SecretKeyFactory object.
    static final SecretKeyFactory
    getInstance(String algorithm)
    Returns a SecretKeyFactory object that converts secret keys of the specified algorithm.
    static final SecretKeyFactory
    getInstance(String algorithm, String provider)
    Returns a SecretKeyFactory object that converts secret keys of the specified algorithm.
    static final SecretKeyFactory
    getInstance(String algorithm, Provider provider)
    Returns a SecretKeyFactory object that converts secret keys of the specified algorithm.
    final KeySpec
    getKeySpec(SecretKey key, Class<?> keySpec)
    Returns a specification (key material) of the given key object in the requested format.
    final Provider
    getProvider()
    Returns the provider of this SecretKeyFactory object.
    final 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 declared in class Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    Modifier and Type
    Method
    Description
    protected Object
    clone()
    Answers a new instance of the same class as the receiver, whose slots have been filled in with the values in the slots of the receiver.
    boolean
    equals(Object o)
    Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison.
    protected void
    finalize()
    Deprecated, for removal: This API element is subject to removal in a future version.
    May cause performance issues, deadlocks and hangs.
    final Class<? extends Object>
    getClass()
    Answers the unique instance of java.lang.Class which represents the class of the receiver.
    int
    hashCode()
    Answers an integer hash code for the receiver.
    final void
    notify()
    Causes one thread which is waiting on the receiver to be made ready to run.
    final void
    notifyAll()
    Causes all threads which are waiting on the receiver to be made ready to run.
    String
    toString()
    Answers a string containing a concise, human-readable description of the receiver.
    final void
    wait()
    Causes the thread which sent this message to be made not ready to run pending some change in the receiver (as indicated by notify or notifyAll).
    final void
    wait(long time)
    Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.
    final void
    wait(long time, int frac)
    Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.

  • Constructor Details

    • 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 Details

    • getInstance

      public 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.

      Implementation Note:
      The JDK Reference Implementation additionally uses the jdk.security.provider.preferred Security property to determine the preferred provider order for the specified algorithm. This may be different from the order of providers returned by Security.getProviders().
      Parameters:
      algorithm - the standard name of the requested secret key algorithm. See the SecretKeyFactory section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names.
      Returns:
      the new SecretKeyFactory object
      Throws:
      NoSuchAlgorithmException - if no Provider supports a SecretKeyFactorySpi implementation for the specified algorithm
      NullPointerException - if algorithm is null
      External Specifications
      See Also:

    • getInstance

      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.

      Parameters:
      algorithm - the standard name of the requested secret key algorithm. See the SecretKeyFactory section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names.
      provider - the name of the provider.
      Returns:
      the new SecretKeyFactory object
      Throws:
      IllegalArgumentException - if the provider is null or empty
      NoSuchAlgorithmException - if a SecretKeyFactorySpi implementation for the specified algorithm is not available from the specified provider
      NoSuchProviderException - if the specified provider is not registered in the security provider list
      NullPointerException - if algorithm is null
      External Specifications
      See Also:

    • getInstance

      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.

      Parameters:
      algorithm - the standard name of the requested secret key algorithm. See the SecretKeyFactory section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names.
      provider - the provider.
      Returns:
      the new SecretKeyFactory object
      Throws:
      IllegalArgumentException - if the provider is null
      NoSuchAlgorithmException - if a SecretKeyFactorySpi implementation for the specified algorithm is not available from the specified Provider object
      NullPointerException - if algorithm is null
      External Specifications
      See Also:

    • 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.