org.bouncycastle.crypto.util

Class EntropyUtil

java.lang.Object

org.bouncycastle.crypto.util.EntropyUtil

public class EntropyUtil
extends java.lang.Object

Utility methods for making use of EntropySources.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	EntropyUtil.WindowStats

Constructor Summary

Constructors

Constructor and Description
EntropyUtil()

Method Summary

Modifier and Type	Method and Description
static EntropyUtil.WindowStats	createStats() Create an initial stats object.
static byte[]	generateSeed(EntropySource entropySource, int numBytes) Generate numBytes worth of entropy from the passed in entropy source.
static java.lang.String	isNotStuck(byte prev, byte[] current) SP 800-90B, 4.4.1: Return true if the entropy source is stuck.
static java.lang.String	isProportionate(EntropyUtil.WindowStats stats, byte[] current) SP 800-90B, 4.4.2: Return true if the entropy is proportionate.

Methods inherited from class java.lang.Object

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

Constructor Detail

EntropyUtil

public EntropyUtil()

Method Detail

generateSeed

public static byte[] generateSeed(EntropySource entropySource,
                                  int numBytes)

Generate numBytes worth of entropy from the passed in entropy source.

Parameters:

entropySource - the entropy source to request the data from.

numBytes - the number of bytes of entropy requested.

Returns:

a byte array populated with the random data.

isNotStuck

public static java.lang.String isNotStuck(byte prev,
                                          byte[] current)

SP 800-90B, 4.4.1: Return true if the entropy source is stuck. By default this will be C calculated for alpha=20, with a H value of 8. The default C value can be set using "org.bouncycastle.ent.stkC".

Parameters:

prev - the last byte of the previous buffer.

current - the current set of entropy samples.

Returns:

null if there's no issue, an error message if there is.

isProportionate

public static java.lang.String isProportionate(EntropyUtil.WindowStats stats,
                                               byte[] current)

SP 800-90B, 4.4.2: Return true if the entropy is proportionate. By default this will be for alpha=20, with a H value of 8. The C value can be set using "org.bouncycastle.ent.adptC"

Parameters:

current - the current sampling of entropy to scan.

Returns:

null if there's no issue, an error message if there is.

createStats

public static EntropyUtil.WindowStats createStats()

Create an initial stats object.

Returns:

a WindowStats object.