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Class java.security.KeyPairGenerator
java.lang.Object
|
+----java.security.KeyPairGenerator
- public abstract class KeyPairGenerator
- extends Object
The KeyPairGenerator class is used to generate pairs of
public and private keys. Key generators are constructed using the
getInstance
factory methods (static methods that
return instances of a given class).
Key generation is an area that sometimes
does not lend itself well to algorithm independence. For example,
it is possible to generate a DSA key pair specifying key family
parameters (p, q and g), while it is not possible to do so for
an RSA key pair. That is, those parameters are applicable to DSA
but not to RSA.
There are therefore 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.
All key pair 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.
The initialize method in this
KeyPairGenerator class
takes these two universally shared
types of arguments.
Since no other parameters are specified when you call this
algorithm-independent initialize
method, all other values, such as algorithm parameters, public
exponent, etc., are defaulted to standard values.
It is sometimes desirable to initialize a key pair generator object
using algorithm-specific semantics. For example, you may want to
initialize a DSA key generator for a given set of parameters
p
, q
and g
,
or an RSA key generator for a given public exponent.
This is done through algorithm-specific standard interfaces. Rather than
calling the algorithm-independent KeyPairGenerator initialize
method, the key pair generator is cast to an algorithm-specific interface
so that one of its specialized parameter initialization methods can be
called. An example is the DSAKeyPairGenerator interface (from
java.security.interfaces
).
See The KeyPairGenerator Class
in the "Java Cryptography Architecture API Specification & Reference"
for more information and examples.
- See Also:
- DSAKeyPairGenerator
-
KeyPairGenerator(String)
- Creates a KeyPairGenerator object for the specified algorithm.
-
generateKeyPair()
- Generates a key pair.
-
getAlgorithm()
- Returns the standard name of the algorithm for this key generator.
-
getInstance(String)
- Generates a KeyPairGenerator object that implements the algorithm
requested, as available in the environment.
-
getInstance(String, String)
-
Generates a KeyPairGenerator object implementing the specified
algorithm, as supplied from the specified provider,
if such an algorithm is available from the provider.
-
initialize(int)
- Initializes the key pair generator for a certain strength using
a system-provided source of randomness.
-
initialize(int, SecureRandom)
- Initializes the key pair generator for a certain strength.
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.
getAlgorithm
public String getAlgorithm()
- Returns the standard name of the algorithm for this key 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 algorithm
requested, as available in the environment.
- 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.
- Throws: NoSuchProviderException
- if the provider is not
available in the environment.
- See Also:
- Provider
initialize
public abstract void initialize(int strength,
SecureRandom random)
- Initializes the key pair generator for a certain strength.
- Parameters:
- strength - the strength of the key. This is an
algorithm-specific metric, such as modulus length.
- random - the source of randomness for this generator.
initialize
public void initialize(int strength)
- Initializes the key pair 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, such as modulus length.
generateKeyPair
public abstract KeyPair generateKeyPair()
- 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.
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