|
|||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | ||||||||
SUMMARY: INNER | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |
java.lang.Object | +--javax.crypto.KeyGenerator
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 initialisation of the object:
Algorithm-Independent Initialisation
All key generators share the concepts of a "strength" and a source of randomness. The measure of strength is universally shared by all algorithms, though it is interpreted differently for different algorithms. There is an init method in this KeyGenerator class that takes these two universally shared types of arguments. There is also one that takes just a strength argument, and uses a system-provided source of randomness, and one that takes just a source of randomness.
Since no other parameters are specified when you call the above algorithm-independent init methods, it is up to the provider what to do about the algorithm-specific parameters (if any) to be associated with each of the keys.
Algorithm-Specific Initialisation
For situations where a set of algorithm-specific parameters already exists, there are two init methods that have an AlgorithmParameterSpec argument. One also has a SecureRandom argument, while the source of randomness is system-provided for the other.
In case the client does not explicitly initialise the KeyGenerator (via a call to an init method), each provider must supply (and document) a default initialisation.
SecretKey
Field Summary | |
static java.lang.String |
ident
|
Constructor Summary | |
protected |
KeyGenerator(KeyGeneratorSpi spi,
java.security.Provider provider,
java.lang.String algorithm)
Creates a KeyGenerator object using the given provider, KeyGeneratorSpi and for the specified algorithm. |
Method Summary | |
SecretKey |
generateKey()
Generates a secret key. |
java.lang.String |
getAlgorithm()
Returns the algorithm name of this KeyGenerator object. |
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.spec.AlgorithmParameterSpec params)
Initialises the 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)
Initialises the key generator with the specified parameter set and a user-provided source of randomness. |
void |
init(int strength)
Initialises this key generator for a certain strength, using a system-provided source of randomness. |
void |
init(int strength,
java.security.SecureRandom random)
Initialises this key generator for a certain strength, using a user-provided source of randomness. |
void |
init(java.security.SecureRandom random)
Initialises the key generator. |
Methods inherited from class java.lang.Object |
clone,
equals,
finalize,
getClass,
hashCode,
notify,
notifyAll,
toString,
wait,
wait,
wait |
Field Detail |
public static final java.lang.String ident
Constructor Detail |
protected KeyGenerator(KeyGeneratorSpi spi, java.security.Provider provider, java.lang.String algorithm)
spi
- the KeyGeneratorSpi to useprovider
- the provider to usealgorithm
- the standard name of the key algorithm. See
Appendix A in the Java Cryptography Architecture API
Specification & Reference for information about standard
algorithm names.Method Detail |
public final java.lang.String getAlgorithm()
public static KeyGenerator getInstance(java.lang.String algorithm) throws java.security.NoSuchAlgorithmException
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.public static KeyGenerator getInstance(java.lang.String algorithm, java.lang.String provider) throws java.security.NoSuchAlgorithmException, java.security.NoSuchProviderException
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 providerProvider
public final java.security.Provider getProvider()
public final void init(java.security.SecureRandom random)
random
- the source of randomness for this generator.public final void init(java.security.spec.AlgorithmParameterSpec params) throws java.security.InvalidAlgorithmParameterException
params
- the key generation parameterspublic final void init(java.security.spec.AlgorithmParameterSpec params, java.security.SecureRandom random) throws java.security.InvalidAlgorithmParameterException
params
- the key generation parametersrandom
- the source of randomness for this key generatorpublic final void init(int strength)
strength
- the strength of the key. This is an algorithm-specific
metric specified in number of bits.public final void init(int strength, java.security.SecureRandom random)
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 generatorpublic SecretKey generateKey()
|
|||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | ||||||||
SUMMARY: INNER | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |