This class generates cryptographic-quality
pseudorandom bytes. Although SecureRandom defines
public constructors, the preferred technique for obtaining a
SecureRandom object is to call one of the static
getInstance( )
factory methods, specifying the desired pseudorandom
number-generation algorithm, and, optionally, the desired provider of
that algorithm. Sun's implementation of Java ships
with an algorithm named "SHA1PRNG"
in the "SUN" provider.
Once you have obtained a
SecureRandom object, call nextBytes(
) to fill an array with pseudorandom bytes. You can also
call any of the methods defined by the Random
superclass to obtain random numbers. The first time one of these
methods is called, the SecureRandom( ) method uses
its generateSeed( ) method to seed itself. If you
have a source of random or very high-quality pseudorandom bytes, you
may provide your own seed by calling setSeed( ).
Repeated calls to setSeed( ) augment the existing
seed instead of replacing it. You can also call
generateSeed( ) to generate seeds for use with
other pseudorandom generators. generateSeed( ) may
use a different algorithm than nextBytes( ) and
may produce higher-quality randomness, usually at the expense of
increased computation time.
public class SecureRandom extends java.util.Random {
// Public Constructors
public SecureRandom( );
public SecureRandom(byte[ ] seed);
// Protected Constructors
1.2 protected SecureRandom(SecureRandomSpi secureRandomSpi, Provider provider);
// Public Class Methods
1.2 public static SecureRandom getInstance(String algorithm)
throws NoSuchAlgorithmException;
1.2 public static SecureRandom getInstance(String algorithm, String provider)
throws NoSuchAlgorithmException, NoSuchProviderException;
1.4 public static SecureRandom getInstance(String algorithm, Provider provider)
throws NoSuchAlgorithmException;
public static byte[ ] getSeed(int numBytes);
// Public Instance Methods
1.2 public byte[ ] generateSeed(int numBytes);
5.0 public String getAlgorithm( ); default:"NativePRNG"
1.2 public final Provider getProvider( );
public void setSeed(byte[ ] seed); synchronized
// Public Methods Overriding Random
public void nextBytes(byte[ ] bytes); synchronized
public void setSeed(long seed);
// Protected Methods Overriding Random
protected final int next(int numBits);
}
Too many methods to list.
