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Class javax.crypto.KeyGenerator

java.lang.Object
    |
    +----javax.crypto.KeyGenerator

public class KeyGenerator
extends java.lang.Object
This class provides the functionality of a (symmetric) key generator.

Key generators are constructed using one of the getInstance class methods of this class.

KeyGenerator objects are reusable, i.e., after a key has been generated, the same KeyGenerator object can be re-used to generate further keys.

There are two ways to generate a key: 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 KeyGenerator (via a call to an init method), each provider must supply (and document) a default initialization.

See Also:
SecretKey, java.security.AlgorithmParameters, java.security.spec.AlgorithmParameterSpec

Constructor Summary
 KeyGenerator(KeyGeneratorSpi keyGenSpi, java.security.Provider provider, java.lang.String algorithm)
Creates a KeyGenerator object.
 

Method Summary
SecretKey  generateKey()
Generates a secret key.
java.lang.String  getAlgorithm()
Returns the standard name of the key algorithm.
static KeyGenerator  getInstance(java.lang.String algorithm)
Generates a KeyGenerator object for the specified algorithm.
static KeyGenerator  getInstance(java.lang.String algorithm, java.lang.String provider)
Generates a KeyGenerator object for the specified key algorithm from the specified provider.
java.security.Provider  getProvider()
Returns the provider of this KeyGenerator object.
void  init(java.security.SecureRandom random)
Initializes this key generator.
void  init(java.security.spec.AlgorithmParameterSpec params)
Initializes this key generator with the specified parameter set, using a system-provided source of randomness.
void  init(java.security.spec.AlgorithmParameterSpec params, java.security.SecureRandom random)
Initializes this key generator with the specified parameter set and a user-provided source of randomness.
void  init(int strength)
Initializes this key generator for a certain strength, using a system-provided source of randomness.
void  init(int strength, java.security.SecureRandom random)
Initializes this key generator for a certain strength, using a user-provided source of randomness.
 
Methods inherited from class java.lang.Object
 clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

KeyGenerator

protected KeyGenerator(KeyGeneratorSpi keyGenSpi,
                       java.security.Provider provider,
                       java.lang.String algorithm)
Creates a KeyGenerator object.
Parameters:
keyGenSpi - the delegate
provider - the provider
algorithm - the algorithm
Method Detail

getAlgorithm

public final java.lang.String getAlgorithm()
Returns the standard name of the key algorithm. See Appendix A in the Java Cryptography Extension API Specification & Reference for information about standard algorithm names.
Returns:
the standard algorithm name.

getInstance

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

getInstance

public static final KeyGenerator getInstance(java.lang.String algorithm,
                                             java.lang.String provider) throws java.security.NoSuchAlgorithmException, java.security.NoSuchProviderException
Generates a KeyGenerator object for the specified key algorithm from the specified provider.
Parameters:
algorithm - the standard name of the requested key algorithm. See Appendix A in the Java Cryptography Extension API Specification & Reference for information about standard algorithm names.
provider - the name of the provider
Returns:
the new KeyGenerator object
Throws:
java.security.NoSuchAlgorithmException - if a key generator for the requested algorithm is not available from the provider
java.security.NoSuchProviderException - if the requested provider is not available
See Also:
java.security.Provider

getProvider

public final java.security.Provider getProvider()
Returns the provider of this KeyGenerator object.
Returns:
the provider of this KeyGenerator object

init

public final void init(java.security.SecureRandom random)
Initializes this key generator.
Parameters:
random - the source of randomness for this generator

init

public final void init(java.security.spec.AlgorithmParameterSpec params) throws java.security.InvalidAlgorithmParameterException
Initializes this key generator with the specified parameter set, using a system-provided source of randomness.
Parameters:
params - the key generation parameters
Throws:
java.security.InvalidAlgorithmParameterException - if the given parameters are inappropriate for this key generator

init

public final void init(java.security.spec.AlgorithmParameterSpec params,
                       java.security.SecureRandom random) throws java.security.InvalidAlgorithmParameterException
Initializes this key generator with the specified parameter set and a user-provided source of randomness.
Parameters:
params - the key generation parameters
random - the source of randomness for this key generator
Throws:
java.security.InvalidAlgorithmParameterException - if params is inappropriate for this key generator

init

public final void init(int strength)
Initializes this key generator for a certain strength, using a system-provided source of randomness.
Parameters:
strength - the strength of the key. This is an algorithm-specific metric specified in number of bits.

init

public final void init(int strength,
                       java.security.SecureRandom random)
Initializes this key generator for a certain strength, using a user-provided source of randomness.
Parameters:
strength - the strength of the key. This is an algorithm-specific metric specified in number of bits.
random - the source of randomness for this key generator

generateKey

public final SecretKey generateKey()
Generates a secret key.
Returns:
the new key

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