SecureRandom


SecureRandom java.security

Java 1.1 serializable

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.

Figure 14-36. java.security.SecureRandom

 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  );   } 

Passed To

Too many methods to list.

Type Of

SignatureSpi.appRandom



Java In A Nutshell
Java In A Nutshell, 5th Edition
ISBN: 0596007736
EAN: 2147483647
Year: 2004
Pages: 1220

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