java.security
Class SecureRandom

java.lang.Object
  java.util.Random
      java.security.SecureRandom

All Implemented Interfaces:

Serializable

public class SecureRandom
extends Random

See Also:

Serialized Form

Constructor Summary

	SecureRandom() Constructs a new instance of this class.
	SecureRandom(byte[] seed) Constructs a new instance of this class.
protected	SecureRandom(SecureRandomSpi secureRandomSpi, Provider provider)

Method Summary

byte[]	generateSeed(int numBytes) Generates a certain number of seed bytes
String	getAlgorithm()
static SecureRandom	getInstance(String algorithm)
static SecureRandom	getInstance(String algorithm, Provider provider)
static SecureRandom	getInstance(String algorithm, String provider) Returns a new SecureRandom which is capable of running the algorithm described by the argument.
Provider	getProvider() Returns the Provider of the secure random represented by the receiver.
static byte[]	getSeed(int numBytes) Returns the given number of seed bytes, computed using the seed generation algorithm used by this class.
protected int	next(int numBits) Returns a pseudo-random uniformly distributed int value of the number of bits specified by the argument bits as described by Donald E.
void	nextBytes(byte[] bytes) Modifies the byte array by a random sequence of bytes generated by this random number generator.
void	setSeed(byte[] seed)
void	setSeed(long seed) Reseeds this random object with the eight bytes described by the representation of the long provided.

Methods inherited from class java.util.Random

nextBoolean, nextDouble, nextFloat, nextGaussian, nextInt, nextInt, nextLong

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SecureRandom

public SecureRandom()

Constructs a new instance of this class. Users are encouraged to use getInstance() instead. An implementation for the highest-priority provider is returned. The instance returned will not have been seeded.

SecureRandom

public SecureRandom(byte[] seed)

Constructs a new instance of this class. Users are encouraged to use getInstance() instead. An implementation for the highest-priority provider is returned. The instance returned will be seeded with the parameter.

Parameters:

seed - bytes forming the seed for this generator.

SecureRandom

protected SecureRandom(SecureRandomSpi secureRandomSpi,
                       Provider provider)

Method Detail

getInstance

public static SecureRandom getInstance(String algorithm)
                                throws NoSuchAlgorithmException

Throws:

NoSuchAlgorithmException

getInstance

public static SecureRandom getInstance(String algorithm,
                                       String provider)
                                throws NoSuchAlgorithmException,
                                       NoSuchProviderException

Returns a new SecureRandom which is capable of running the algorithm described by the argument. The result will be an instance of a subclass of SecureRandomSpi which implements that algorithm.

Parameters:

algorithm - java.lang.String Name of the algorithm desired

provider - java.security.Provider Provider which has to implement the algorithm

Returns:

SecureRandom a concrete implementation for the algorithm desired.

Throws:

NoSuchAlgorithmException - If the algorithm cannot be found

NoSuchProviderException

getInstance

public static SecureRandom getInstance(String algorithm,
                                       Provider provider)
                                throws NoSuchAlgorithmException

Throws:

NoSuchAlgorithmException

getProvider

public final Provider getProvider()

Returns the Provider of the secure random represented by the receiver.

Returns:

Provider an instance of a subclass of java.security.Provider

getAlgorithm

public String getAlgorithm()

setSeed

public void setSeed(byte[] seed)

setSeed

public void setSeed(long seed)

Reseeds this random object with the eight bytes described by the representation of the long provided.

Overrides:

setSeed in class Random

Parameters:

seed - long Number whose representation to use to reseed the receiver.

See Also:

Random.next(int), Random.Random(), Random.Random(long)

nextBytes

public void nextBytes(byte[] bytes)

Description copied from class: Random

Modifies the byte array by a random sequence of bytes generated by this random number generator.

Overrides:

nextBytes in class Random

Parameters:

bytes - non-null array to contain the new random bytes

See Also:

Random.next(int)

next

protected final int next(int numBits)

Description copied from class: Random

Returns a pseudo-random uniformly distributed int value of the number of bits specified by the argument bits as described by Donald E. Knuth in The Art of Computer Programming, Volume 2: Seminumerical Algorithms, section 3.2.1.

Overrides:

next in class Random

Parameters:

numBits - number of bits of the returned value

Returns:

int a pseudo-random generated int number

See Also:

Random.nextBytes(byte[]), Random.nextDouble(), Random.nextFloat(), Random.nextInt(), Random.nextInt(int), Random.nextGaussian(), Random.nextLong()

getSeed

public static byte[] getSeed(int numBytes)

Returns the given number of seed bytes, computed using the seed generation algorithm used by this class.

Parameters:

numBytes - int the given number of seed bytes

Returns:

byte[] The seed bytes generated

generateSeed

public byte[] generateSeed(int numBytes)

Generates a certain number of seed bytes

Parameters:

numBytes - int Number of seed bytes to generate

Returns:

byte[] The seed bytes generated