Some countries place legal restrictions on the use of cryptographic algorithms. In some cases, a program may be exempt from these restrictions if it implements an "exemption mechanism" such as key recovery, key escrow, or key weakening. This class defines a very general API to such mechanism. This class is rarely used, and is not supported in the default implementation provided by Sun. Using this class successfully is quite complex, and is beyond the scope of this reference. For details, see the discussion "How to Make Applications `Exempt' from Cryptographic Restrictions" in the JCE Reference Guide which is part of the standard bundle of documentation shipped by Sun with the JDK.

public class ExemptionMechanism {
// Protected Constructors
     protected ExemptionMechanism(ExemptionMechanismSpi exmechSpi, 
        java.security.Provider provider, String mechanism);  
// Public Class Methods
     public static final ExemptionMechanism getInstance(String algorithm)
        throws java.security.NoSuchAlgorithmException;  
     public static final ExemptionMechanism getInstance(String algorithm, 
        String provider) throws java.security.NoSuchAlgorithmException, 
        java.security.NoSuchProviderException;  
     public static final ExemptionMechanism getInstance(String algorithm, 
        java.security.Provider provider) 
        throws java.security.NoSuchAlgorithmException;  
// Public Instance Methods
     public final byte[ ] genExemptionBlob( ) throws IllegalStateException, 
        ExemptionMechanismException;  
     public final int genExemptionBlob(byte[ ] output) 
        throws IllegalStateException, ShortBufferException, 
        ExemptionMechanismException;  
     public final int genExemptionBlob(byte[ ] output, int outputOffset) 
        throws IllegalStateException, ShortBufferException, 
        ExemptionMechanismException;  
     public final String getName( );  
     public final int getOutputSize(int inputLen) throws IllegalStateException;  
     public final java.security.Provider getProvider( );  
     public final void init(java.security.Key key) 
         throws java.security.InvalidKeyException, 
         ExemptionMechanismException;  
     public final void init(java.security.Key key, 
         java.security.spec.AlgorithmParameterSpec params) 
         throws java.security.InvalidKeyException, 
         java.security.InvalidAlgorithmParameterException, 
         ExemptionMechanismException;  
     public final void init(java.security.Key key, 
         java.security.AlgorithmParameters params) 
         throws java.security.InvalidKeyException, 
         java.security.InvalidAlgorithmParameterException, 
         ExemptionMechanismException;  
     public final boolean isCryptoAllowed(java.security.Key key) 
         throws ExemptionMechanismException;  
// Protected Methods Overriding Object
     protected void finalize( );  
}

Returned By

Cipher.getExemptionMechanism( )