http://www.bouncycastle.org/java.html: The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.5 to JDK 1.8.
  • The Legion of the Bouncy Castle Inc. 
package org.bouncycastle.crypto.prng;


Base interface describing an entropy source for a DRBG.

/**
 * Base interface describing an entropy source for a DRBG.
 */
public interface EntropySource
{
    
Return whether or not this entropy source is regarded as prediction resistant.

Returns:true if it is, false otherwise.
/**
     * Return whether or not this entropy source is regarded as prediction resistant.
     *
     * @return true if it is, false otherwise.
     */
    boolean isPredictionResistant();

    
Return a byte array of entropy.

Returns: entropy bytes.
/**
     * Return a byte array of entropy.
     *
     * @return  entropy bytes.
     */
    byte[] getEntropy();

    
Return the number of bits of entropy this source can produce.

Returns:size in bits of the return value of getEntropy.
/**
     * Return the number of bits of entropy this source can produce.
     *
     * @return size in bits of the return value of getEntropy.
     */
    int entropySize();
}