Secret key Factory Keyfactory in Java

I. Overview

This class is located under the Java.security package, declared: Publicclasskeyfactory extends Object

The key factory is used to convert a key (an opaque encryption Key key of type) into a key specification (a transparent representation of the underlying key material) and vice versa.

The key factory is bidirectional. That is, they allow for the construction of opaque key objects based on a given key specification (keying material), and also to obtain the underlying keying material for the key object in the appropriate format.

There can be more than one compatible key specification for the same key. For example, you can use DSAPublicKeySpec or X509EncodedKeySpec specify a DSA public key. A key factory can be used to convert between compatible key specifications.

The following is an example of how to instantiate a DSA public key based on its encoding using a key factory. Suppose Alice received a digital signature from Bob. Bob also sends her public key (in encoded format) to verify his signature. Then Alice performs the following actions:

X509encodedkeyspec Bobpubkeyspec = new X509encodedkeyspec (Bobencodedpubkey); Keyfactory keyfactory = keyfactory.getinstance ("DSA"); PublicKey Bobpubkey = Keyfactory.generatepublic (Bobpubkeyspec); Signature sig = Signature.getinstance ("DSA"); Sig.initverify (Bobpubkey); Sig.update (data); Sig.verify (signature);

Second, the construction method

keyfactory (Keyfactoryspi keyfacspi,provider Provider, String algorithm)  Creates a Keyfactory object.

  
 

   
 
 

 
    
  Parameters: 
    
  keyFacSpi 
    -Agent 
    
  provider 
    -Provided by 
    
  algorithm 
    -With this 
    keyfactory 
    The associated algorithm name
 
 
 
 
 
 
 
 

   
 
  
  
 

   
 
 

 
    

   
 
  
  
 

   
 
 

 
    Iii. details of the method

   
 
  
  
 

   
 
 

 
    1. Public 
    Static Keyfactory 
      
    
  getinstance
    (String 
    algorithm)  
    throws NoSuchAlgorithmException returns the Keyfactory object that transforms the Public/private keyword of the specified algorithm
 
 
 
 
   
 
  
  
 

   
 
 

 
    
  
This method iterates through the list of registered security providers starting with the preferred Provider. Returns a new Keyfactory object that encapsulates the implementation of the KEYFACTORYSPI, taken from the first Provider that supports a specified algorithm.
 
    
  
Note that the list of registered providers can be obtained by means of the Security.getProviders() method.

   
 
  
  
 

   
 
 

 
    
  Parameters: 
    
  algorithm 
    -the name of the request key algorithm. 
 
 

   
 
  
  
 

   
 
 

 
    

   
 
  
  
 

   
 
 

 
    
  returns: the new Keyfactory object.
   
 
  
  
 

   
 
 

  
  
 

   
 
 

 
    
  thrown: 
    
  NoSuchAlgorithmException -If no Provider supports the KEYFACTORYSPI implementation of the specified algorithm. 
 
   
 
  
  
 

   
 
 

  
  
 

   
 
 

  
    2, public static keyfactory 
    
  getinstance(String algorithm,string provider) throws NoSuchAlgorithmException, Nosuchproviderexception returns a Keyfactory object that transforms the Public/private keyword of the specified algorithm.
    
  
Returns a new Keyfactory object that encapsulates the implementation of the KEYFACTORYSPI, taken from the specified provider. Specifies that the provider must be registered in the Security provider list.
 
    
  
Note that the list of registered providers can be obtained by means of the Security.getProviders() method.

   
 
  
  
 

   
 
 

 
    
  Parameters:

   
 
  
  
 

   
 
 
 
    
  algorithm -The name of the request key algorithm.
For information on standard algorithm names, see Appendix A in Java Cryptography Architecture API Specification & Reference. 
 
   
 
  
  
 

   
 
 
 
    
  provider -The name of the provider. 
 
   
 
  
  
 

   
 
 

 
    
  Return:

   
 
  
  
 

   
 
 

  
    the new Keyfactory object. 
   
 
  
  
 

   
 
 

 
    
  Thrown: 

   
 
  
  
 

   
 
 
 
    
  NoSuchAlgorithmException -If the KEYFACTORYSPI implementation of the specified algorithm cannot be obtained from the specified provider. 
 
   
 
  
  
 

   
 
 
 
    
  NoSuchProviderException -If the specified provider is not registered in the Security provider list. 
 
   
 
  
  
 

   
 
 
 
    
  IllegalArgumentException -If the name of the provider is null or empty. 
 
   
 
  
  
 

   
 
 

 
    3. Public 
    Static Keyfactory 
      
    
  getinstance
    (String 
    algorithm, 
     Provider 
    Provider)  c9> throws NoSuchAlgorithmException
 
 
 
 
 
   
 
  
  
 

   
 
 

  
  
 

   
 
 

  
    returns the Keyfactory object that transforms the Public/private keyword of the specified algorithm.
    
  
Returns a new Keyfactory object that encapsulates the implementation of the KEYFACTORYSPI, which is taken from the specified Provider object. Note that the specified Provider object does not need to be registered in the provider list.
 
    
  
 
   
 
  
  
 

   
 
 

 
    
  
 
   
 
    Parameters: 
   
 
   
 
    algorithm -The name of the request key algorithm. For information on standard algorithm names, see Appendix A in Java Cryptography Architecture API Specification & Reference. 
   
 
   
 
    provider -provider. 
   
 
   
 
    Return: 
   
 
   

     The new Keyfactory object. 
   
 
   
 
    Thrown: 
   
 
   
 
    NoSuchAlgorithmException -If the KEYFACTORYSPI implementation of the specified algorithm cannot be obtained from the specified Provider object. 
   
 
   
 
    IllegalArgumentException -If the specified provider is null. 
   
 
  
 4. Public 
    final Provider 
      
    
  getprovider
    () returns the provider of this key factory object. 
 
 

   
 
  
  
 

   
 
 

 
    

   
 
  
  
 

   
 
 

 
    5. Public 
    Final String 
      
    
  getalgorithm
    () Gets the name of the algorithm associated with this keyfactory . 
 
 
 

   
 
  
  
 

   
 
 

 
    

   
 
  
  
 

   
 
 

 
    6. Public 
    Final PublicKey 
      
    
  generatepublic
    (KeySpec 
    KeySpec) 
     throws Invalidkeyspecexception
 
 
 
 
   
 
  
  
 

   
 
 

  
    Generates a public key object based on the provided key specification (keying material).
   
 
  
  
 

   
 
 

  
  
 

   
 
 

 
    
  Parameters:

   
 
  
  
 

   
 
 
 
    
  keySpec -The specification of the public key (keying material). 
 
   
 
  
  
 

   
 
 

 
    
  Return:

   
 
  
  
 

   
 
 

  
    public key. 
   
 
  
  
 

   
 
 

 
    
  Thrown: 

   
 
  
  
 

   
 
 
 
    
  InvalidKeySpecException -If the given key specification does not fit this key factory to generate the public key. 
 
   
 
  
  
 

   
 
 

  
    7. Public 
    final privatekey 
      
    
  generateprivate
    (KeySpec 
    KeySpec) 
     th
Rows invalidkeyspecexception generates a private key object based on the supplied key specification (keying material). 
 
 
 
   
 
  
  
 

   
 
 

  
  
 

   
 
 

 
    
  Parameters:

   
 
  
  
 

   
 
 
 
    
  keySpec -The specification of the private key (keying material). 
 
   
 
  
  
 

   
 
 

 
    
  Return:

   
 
  
  
 

  
   The 
   
 
 

  
    private key. 
   
 
  
  
 

   
 
 

 
    
  Thrown: 

   
 
  
  
 

   
 
 
 
    
  InvalidKeySpecException -If the given key specification does not fit this key factory to generate the private key. 
 
   
 
  
  
 

   
 
 

  
    8. Public 
    final <t extends KeySpec 
    > T  
    
  getkeyspec
    (key 
    key, 
      
 Class 
    <T> keySpec) 
     throws Invalidkeyspecexception returns the specification (keying material) for a given key object. 
    
  keySpecidentifies the canonical class that should accept the return keying material. For example, it may be 
    
  DSAPublicKeySpec.class that the keying material should be returned to 
    
  DSAPublicKeySpec an instance of the class.
 
 
 
 
   
 
  
  
 

   
 
 

  
  
 

   
 
 

 
    
  Parameters:

   
 
  
  
 

   
 
 
 
    
  key -Key. 
 
   
 
  
  
 

   
 
 
 
    
  keySpec -The canonical class that returns the keying material should be accepted. 
 
   
 
  
  
 

   
 
 

 
    
  Return:

   
 
  
  
 

   
 
 

  
    the underlying key specification (keying material) in the request specification class instance. 
   
 
  
  
 

   
 
 

 
    
  Thrown: 

   
 
  
  
 

   
 
 
 
    
  InvalidKeySpecException -If the requested key specification does not fit the given key, or the given key cannot be processed (for example, a given key has an unrecognized algorithm or format). 
 
   
 
  
  
 

   
 
 

  
    9. Public 
    final Key 
      
    
  translatekey
    (key 
    key) 
     throws Invalidkey Exception converts a provider may be an unknown or untrusted key object to the corresponding key object for this key factory.
 
 
 
   
 
  
  
 

   
 
 

 
    
  
 
   
 
    Parameters: 
   
 
   
 
    key-the provider is an unknown or untrusted key object. 
   
 
   
 
    Return: 
   
 
   

     The converted key. 
   
 
   
 
    Thrown: 
   
 
   
 
    InvalidKeyException-If this key factory cannot process the given key. 
   
 
  

   
 
  

Secret key Factory Keyfactory in Java