gnu.crypto.prng

Class CSPRNG

public class CSPRNG extends BasePRNG

An entropy pool-based pseudo-random number generator based on the PRNG in Peter Gutmann's cryptlib (http://www.cs.auckland.ac.nz/~pgut001/cryptlib/).

The basic properties of this generator are:

  1. The internal state cannot be determined by knowledge of the input.
  2. It is resistant to bias introduced by specific inputs.
  3. The output does not reveal the state of the generator.
Field Summary
static StringBLOCKING
Property name for whether or not to wait for the slow poll to complete, passed as a Boolean.
static StringFILE_SOURCES
Property name for the list of files to read for random values.
static StringOTHER_SOURCES
Property name for a list of other sources of entropy.
static StringPROGRAM_SOURCES
Property name for the list of programs to execute, and use the output as new random bytes.
static StringURL_SOURCES
Property name for the list of URLs to poll for random values.
Constructor Summary
CSPRNG()
Method Summary
voidaddQuality(double quality)
voidaddRandomByte(byte b)
Add a single random byte to the randomness pool.
voidaddRandomBytes(byte[] buf, int off, int len)
Add an array of bytes into the randomness pool.
Objectclone()
voidfillBlock()
protected voidfinalize()
doublegetQuality()
static IRandomgetSystemInstance()

Create and initialize a CSPRNG instance with the "system" parameters; the files, URLs, programs, and EntropySource sources used by the instance are derived from properties set in the system Properties.

All properties are of the from name.N, where name is the name of the source, and N is an integer (staring at 1) that indicates the preference number for that source.

The following vales for name are used here:

gnu.crypto.csprng.file

These properties are file sources, passed as the FILE_SOURCES parameter of the instance.

voidsetup(Map attrib)

Field Detail

BLOCKING

public static final String BLOCKING
Property name for whether or not to wait for the slow poll to complete, passed as a Boolean. The default value is true.

FILE_SOURCES

public static final String FILE_SOURCES
Property name for the list of files to read for random values. The mapped value is a list with the following values:
  1. A Double, indicating the suggested quality of this source. This value must be between 0 and 100.
  2. An Integer, indicating the number of bytes to skip in the file before reading bytes. This can be any nonnegative value.
  3. An Integer, indicating the number of bytes to read.
  4. A String, indicating the path to the file.

See Also: SimpleList

OTHER_SOURCES

public static final String OTHER_SOURCES
Property name for a list of other sources of entropy. The mapped value must be a list of EntropySource objects.

PROGRAM_SOURCES

public static final String PROGRAM_SOURCES
Property name for the list of programs to execute, and use the output as new random bytes. The mapped property is formatted similarly an in FILE_SOURCES and URL_SOURCES, except the fourth member is a String of the program to execute.

URL_SOURCES

public static final String URL_SOURCES
Property name for the list of URLs to poll for random values. The mapped value is a list formatted similarly as in FILE_SOURCES, but the fourth member is a URL.

Constructor Detail

CSPRNG

public CSPRNG()

Method Detail

addQuality

void addQuality(double quality)

addRandomByte

public void addRandomByte(byte b)
Add a single random byte to the randomness pool. Note that this method will not increment the pool's quality counter (this can only be done via a source provided to the setup method).

Parameters: b The byte to add.

addRandomBytes

public void addRandomBytes(byte[] buf, int off, int len)
Add an array of bytes into the randomness pool. Note that this method will not increment the pool's quality counter (this can only be done via a source provided to the setup method).

Parameters: buf The byte array. off The offset from whence to start reading bytes. len The number of bytes to add.

Throws: ArrayIndexOutOfBoundsException If off or len are out of the range of buf.

clone

public Object clone()

fillBlock

public void fillBlock()

finalize

protected void finalize()

getQuality

double getQuality()

getSystemInstance

public static IRandom getSystemInstance()

Create and initialize a CSPRNG instance with the "system" parameters; the files, URLs, programs, and EntropySource sources used by the instance are derived from properties set in the system Properties.

All properties are of the from name.N, where name is the name of the source, and N is an integer (staring at 1) that indicates the preference number for that source.

The following vales for name are used here:

gnu.crypto.csprng.file

These properties are file sources, passed as the FILE_SOURCES parameter of the instance. The property value is a 4-tuple formatted as:

quality ; offset ; count ; path

The parameters are mapped to the parameters defined for FILE_SOURCES. Leading or trailing spaces on any item are trimmed off.

gnu.crypto.csprng.url

These properties are URL sources, passed as the URL_SOURCES parameter of the instance. The property is formatted the same way as file sources, but the path argument must be a valid URL.

gnu.crypto.csprng.program

These properties are program sources, passed as the PROGRAM_SOURCES parameter of the instance. This property is formatted the same way as file and URL sources, but the last argument is a program and its arguments.

gnu.crypto.cspring.other

These properties are other sources, passed as the OTHER_SOURCES parameter of the instance. The property value must be the full name of a class that implements the EntropySource interface and has a public no-argument constructor.

Finally, a boolean property "gnu.crypto.csprng.blocking" can be set to the desired value of BLOCKING.

An example of valid properties would be:

 gnu.crypto.csprng.blocking=true

 gnu.crypto.csprng.file.1=75.0;0;256;/dev/random
 gnu.crypto.csprng.file.2=10.0;0;100;/home/user/file

 gnu.crypto.csprng.url.1=5.0;0;256;http://www.random.org/cgi-bin/randbyte?nbytes=256
 gnu.crypto.csprng.url.2=0;256;256;http://slashdot.org/

 gnu.crypto.csprng.program.1=0.5;0;10;last -n 50
 gnu.crypto.csprng.program.2=0.5;0;10;tcpdump -c 5

 gnu.crypto.csprng.other.1=foo.bar.MyEntropySource
 gnu.crypto.csprng.other.2=com.company.OtherEntropySource
 

setup

public void setup(Map attrib)
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