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java.security
abstract public class: KeyPairGenerator [javadoc | source]
java.lang.Object
   java.security.KeyPairGeneratorSpi
      java.security.KeyPairGenerator

Direct Known Subclasses:
    Delegate, DummyKeyPairGenerator

The KeyPairGenerator class is used to generate pairs of public and private keys. Key pair generators are constructed using the getInstance factory methods (static methods that return instances of a given class).

A Key pair generator for a particular algorithm creates a public/private key pair that can be used with this algorithm. It also associates algorithm-specific parameters with each of the generated keys.

There are two ways to generate a key pair: in an algorithm-independent manner, and in an algorithm-specific manner. The only difference between the two is the initialization of the object:

In case the client does not explicitly initialize the KeyPairGenerator (via a call to an initialize method), each provider must supply (and document) a default initialization. For example, the Sun provider uses a default modulus size (keysize) of 1024 bits.

Note that this class is abstract and extends from KeyPairGeneratorSpi for historical reasons. Application developers should only take notice of the methods defined in this KeyPairGenerator class; all the methods in the superclass are intended for cryptographic service providers who wish to supply their own implementations of key pair generators.

Every implementation of the Java platform is required to support the following standard KeyPairGenerator algorithms and keysizes in parentheses:

These algorithms are described in the KeyPairGenerator section of the Java Cryptography Architecture Standard Algorithm Name Documentation. Consult the release documentation for your implementation to see if any other algorithms are supported.
Field Summary
 Provider provider     
Constructor:
 protected KeyPairGenerator(String algorithm) 
    Creates a KeyPairGenerator object for the specified algorithm.
Method from java.security.KeyPairGenerator Summary:
disableFailover,   genKeyPair,   generateKeyPair,   getAlgorithm,   getInstance,   getInstance,   getInstance,   getProvider,   initialize,   initialize,   initialize,   initialize
Methods from java.security.KeyPairGeneratorSpi:
generateKeyPair,   initialize,   initialize
Methods from java.lang.Object:
clone,   equals,   finalize,   getClass,   hashCode,   notify,   notifyAll,   toString,   wait,   wait,   wait
Method from java.security.KeyPairGenerator Detail:
  void disableFailover() 
 public final KeyPair genKeyPair() 
    Generates a key pair.

    If this KeyPairGenerator has not been initialized explicitly, provider-specific defaults will be used for the size and other (algorithm-specific) values of the generated keys.

    This will generate a new key pair every time it is called.

    This method is functionally equivalent to generateKeyPair .

 public KeyPair generateKeyPair() 
    Generates a key pair.

    If this KeyPairGenerator has not been initialized explicitly, provider-specific defaults will be used for the size and other (algorithm-specific) values of the generated keys.

    This will generate a new key pair every time it is called.

    This method is functionally equivalent to genKeyPair .

 public String getAlgorithm() 
 public static KeyPairGenerator getInstance(String algorithm) throws NoSuchAlgorithmException 
    Returns a KeyPairGenerator object that generates public/private key pairs for the specified algorithm.

    This method traverses the list of registered security Providers, starting with the most preferred Provider. A new KeyPairGenerator object encapsulating the KeyPairGeneratorSpi 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.

 public static KeyPairGenerator getInstance(String algorithm,
    String provider) throws NoSuchAlgorithmException, NoSuchProviderException 
    Returns a KeyPairGenerator object that generates public/private key pairs for the specified algorithm.

    A new KeyPairGenerator object encapsulating the KeyPairGeneratorSpi 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.

 public static KeyPairGenerator getInstance(String algorithm,
    Provider provider) throws NoSuchAlgorithmException 
    Returns a KeyPairGenerator object that generates public/private key pairs for the specified algorithm.

    A new KeyPairGenerator object encapsulating the KeyPairGeneratorSpi implementation from the specified Provider object is returned. Note that the specified Provider object does not have to be registered in the provider list.

 public final Provider getProvider() 
    Returns the provider of this key pair generator object.
 public  void initialize(int keysize) 
    Initializes the key pair generator for a certain keysize using a default parameter set and the SecureRandom implementation of the highest-priority installed provider as the source of randomness. (If none of the installed providers supply an implementation of SecureRandom, a system-provided source of randomness is used.)
 public  void initialize(AlgorithmParameterSpec params) throws InvalidAlgorithmParameterException 
    Initializes the key pair generator using the specified parameter set and the SecureRandom implementation of the highest-priority installed provider as the source of randomness. (If none of the installed providers supply an implementation of SecureRandom, a system-provided source of randomness is used.).

    This concrete method has been added to this previously-defined abstract class. This method calls the KeyPairGeneratorSpi initialize method, passing it params and a source of randomness (obtained from the highest-priority installed provider or system-provided if none of the installed providers supply one). That initialize method always throws an UnsupportedOperationException if it is not overridden by the provider.

 public  void initialize(int keysize,
    SecureRandom random) 
    Initializes the key pair generator for a certain keysize with the given source of randomness (and a default parameter set).
 public  void initialize(AlgorithmParameterSpec params,
    SecureRandom random) throws InvalidAlgorithmParameterException 
    Initializes the key pair generator with the given parameter set and source of randomness.

    This concrete method has been added to this previously-defined abstract class. This method calls the KeyPairGeneratorSpi initialize method, passing it params and random. That initialize method always throws an UnsupportedOperationException if it is not overridden by the provider.