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Class java.security.KeyPairGenerator

java.lang.Object
    |
    +----java.security.KeyPairGeneratorSpi
            |
            +----java.security.KeyPairGenerator

public abstract class KeyPairGenerator
extends KeyPairGeneratorSpi
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 (strength) 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, and ignore all the methods in the superclass.

See Also:
AlgorithmParameterSpec

Constructor Summary
 KeyPairGenerator(String algorithm)
Creates a KeyPairGenerator object for the specified algorithm.
 

Method Summary
KeyPair  genKeyPair()
Generates a key pair.
String  getAlgorithm()
Returns the standard name of the algorithm for this key pair generator.
static KeyPairGenerator  getInstance(String algorithm)
Generates a KeyPairGenerator object that implements the specified digest algorithm.
static KeyPairGenerator  getInstance(String algorithm, String provider)
Generates a KeyPairGenerator object implementing the specified algorithm, as supplied from the specified provider, if such an algorithm is available from the provider.
Provider  getProvider()
Returns the provider of this key pair generator object.
void  initialize(int strength)
Initializes the key pair generator for a certain strength using a system-provided source of randomness and the default parameter set.
void  initialize(AlgorithmParameterSpec params)
Initializes the key pair generator using the specified parameter set and a system-provided source of randomness.
 
Methods inherited from class java.security.KeyPairGeneratorSpi
 generateKeyPair, initialize, initialize
 
Methods inherited from class java.lang.Object
 clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

KeyPairGenerator

protected KeyPairGenerator(String algorithm)
Creates a KeyPairGenerator object for the specified algorithm.
Parameters:
algorithm - the standard string name of the algorithm. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard algorithm names.
Method Detail

getAlgorithm

public String getAlgorithm()
Returns the standard name of the algorithm for this key pair generator. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard algorithm names.
Returns:
the standard string name of the algorithm.

getInstance

public static KeyPairGenerator getInstance(String algorithm) throws NoSuchAlgorithmException
Generates a KeyPairGenerator object that implements the specified digest algorithm. If the default provider package provides an implementation of the requested digest algorithm, an instance of KeyPairGenerator containing that implementation is returned. If the algorithm is not available in the default package, other packages are searched.
Parameters:
algorithm - the standard string name of the algorithm. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard algorithm names.
Returns:
the new KeyPairGenerator object.
Throws:
NoSuchAlgorithmException - if the algorithm is not available in the environment.

getInstance

public static KeyPairGenerator getInstance(String algorithm,
                                           String provider) throws NoSuchAlgorithmException, NoSuchProviderException
Generates a KeyPairGenerator object implementing the specified algorithm, as supplied from the specified provider, if such an algorithm is available from the provider.
Parameters:
algorithm - the standard string name of the algorithm. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard algorithm names.
provider - the string name of the provider.
Returns:
the new KeyPairGenerator object.
Throws:
NoSuchAlgorithmException - if the algorithm is not available from the provider.
NoSuchProviderException - if the provider is not available in the environment.
See Also:
Provider

getProvider

public final Provider getProvider()
Returns the provider of this key pair generator object.
Returns:
the provider of this key pair generator object

initialize

public void initialize(int strength)
Initializes the key pair generator for a certain strength using a system-provided source of randomness and the default parameter set.
Parameters:
strength - the strength of the key. This is an algorithm-specific metric, such as modulus length, specified in number of bits.

initialize

public void initialize(AlgorithmParameterSpec params) throws InvalidAlgorithmParameterException
Initializes the key pair generator using the specified parameter set and a system-provided source of randomness.

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

Parameters:
params - the parameter set used to generate the keys.
Throws:
InvalidAlgorithmParameterException - if the given parameters are inappropriate for this key pair generator.

genKeyPair

public final KeyPair genKeyPair()
Generates a key pair. Unless an initialization method is called using a KeyPairGenerator interface, algorithm-specific defaults will be used. This will generate a new key pair every time it is called.
Returns:
the generated key pair

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