This class defines an API for translating a secret key between its opaque SecretKey representation and its transparent javax.crypto.SecretKeySpec representation. It is much like java.security.KeyFactory, except that it works with secret (or symmetric) keys rather than with public and private (asymmetric) keys. SecretKeyFactory is algorithm-independent and provider-based, so you must obtain a SecretKeyFactory object by calling one of the static getInstance( ) factory methods and specifying the name of the desired secret-key algorithm and, optionally, the name of the provider whose implementation is desired. In Java 5.0, the "SunJCE" provider provides SecretKeyFactory implementations for algorithms with the following names:

Once you have obtained a SecretKeyFactory, use generateSecret( ) to create a SecretKey from a java.security.spec.KeySpec (or its subclass, javax.crypto.spec.SecretKeySpec). Or call getKeySpec( ) to obtain a KeySpec for a Key object. Because there can be more than one suitable type of KeySpec, getKeySpec( ) requires a Class object to specify the type of the KeySpec to be created. See also DESKeySpec, DESedeKeySpec, and PBEKeySpec in the javax.crypto.spec package.

public class SecretKeyFactory {
// Protected Constructors
     protected SecretKeyFactory(SecretKeyFactorySpi keyFacSpi, 
        java.security.Provider provider, String algorithm);  
// Public Class Methods
     public static final SecretKeyFactory getInstance(String algorithm) 
        throws java.security.NoSuchAlgorithmException;  
     public static final SecretKeyFactory getInstance(String algorithm, 
        java.security.Provider provider) 
        throws java.security.NoSuchAlgorithmException;  
     public static final SecretKeyFactory getInstance(String algorithm, 
        String provider) throws java.security.NoSuchAlgorithmException, 
        java.security.NoSuchProviderException;  
// Public Instance Methods
     public final SecretKey generateSecret(java.security.spec.KeySpec keySpec) 
        throws java.security.spec.InvalidKeySpecException;  
     public final String getAlgorithm( );  
     public final java.security.spec.KeySpec getKeySpec(SecretKey key, Class keySpec) 
        throws java.security.spec.InvalidKeySpecException;  
     public final java.security.Provider getProvider( );  
     public final SecretKey translateKey(SecretKey key) 
        throws java.security.InvalidKeyException;  
}