net.i2p.util.NativeBigInteger

All Implemented Interfaces:: Serializable, Comparable<BigInteger>

public class NativeBigInteger
extends BigInteger

BigInteger that takes advantage of the jbigi library for the modPow operation, which accounts for a massive segment of the processing cost of asymmetric crypto. The jbigi library itself is basically just a JNI wrapper around the GMP library - a collection of insanely efficient routines for dealing with big numbers.

There are three environmental properties for configuring this component:

jbigi.enable: whether to use the native library (defaults to "true")
jbigi.impl: select which resource to use as the native implementation
jbigi.ref: the file specified in this parameter may contain a resource name to override jbigi.impl (defaults to "jbigi.cfg")

If jbigi.enable is set to false, this class won't even attempt to use the native library, but if it is set to true (or is not specified), it will first check the platform specific library path for the "jbigi" library, as defined by Runtime.loadLibrary(java.lang.String) - e.g. C:\windows\jbigi.dll or /lib/libjbigi.so, as well as the CLASSPATH for a resource named 'jbigi'. If that fails, it reviews the jbigi.impl environment property - if that is set, it checks all of the components in the CLASSPATH for the file specified and attempts to load it as the native library. If jbigi.impl is not set, it uses the jcpuid library described below. If there is still no matching resource, or if that resource is not a valid OS/architecture specific library, the NativeBigInteger will revert to using the pure java implementation.

When attempting to load the native implementation as a resource from the CLASSPATH, the NativeBigInteger will make use of the jcpuid component which runs some assembly code to determine the current CPU implementation, such as "pentium4" or "k623". We then use that, combined with the OS, to build an optimized resource name - e.g. "net/i2p/util/libjbigi-freebsd-pentium4.so" or "net/i2p/util/jbigi-windows-k623.dll". If that resource exists, we use it. If it doesn't (or the jcpuid component fails), we try a generic native implementation using "none" for the CPU (ala "net/i2p/util/jbigi-windows-none.dll").

Running this class by itself does a basic unit test and benchmarks the NativeBigInteger.modPow vs. the BigInteger.modPow by running a 2Kbit op 100 times. At the end of each test, if the native implementation is loaded this will output something like:

  native run time:        6090ms (60ms each)
  java run time:          68067ms (673ms each)
  native = 8.947066860593239% of pure java time

If the native implementation is not loaded, it will start by saying:

  WARN: Native BigInteger library jbigi not loaded - using pure java

Then go on to run the test, finally outputting:

  java run time:  64653ms (640ms each)
  However, we couldn't load the native library, so this doesn't test much

See Also:: Serialized Form

Field Summary

Fields inherited from class java.math.BigInteger
ONE, TEN, TWO, ZERO

Constructor Summary

Constructors
Constructor	Description
`NativeBigInteger(byte[] val)`
`NativeBigInteger(int signum, byte[] magnitude)`
`NativeBigInteger(int bitlen, int certainty, Random rnd)`
`NativeBigInteger(int numbits, Random rnd)`
`NativeBigInteger(String val)`
`NativeBigInteger(String val, int radix)`
`NativeBigInteger(BigInteger integer)`	Creates a new NativeBigInteger with the same value as the supplied BigInteger.

Method Summary

Modifier and Type	Method	Description
`static String`	`cpuModel()`
`static String`	`cpuType()`
`boolean`	`equals(Object o)`
`static int`	`getJbigiVersion()`	Get the jbigi version
`static String`	`getLibGMPVersion()`	Get the libgmp version
`static String`	`getLoadedResourceName()`	The name of the library loaded, if known.
`int`	`hashCode()`
`static boolean`	`isNative()`
`static String`	`loadStatus()`
`static void`	`main(String[] args)`	Compare the BigInteger.modPow vs the NativeBigInteger.modPow of some really big (2Kbit) numbers 100 different times and benchmark the performance.
`BigInteger`	`modInverse(BigInteger m)`
`BigInteger`	`modPow(BigInteger exponent, BigInteger m)`
`BigInteger`	`modPowCT(BigInteger exponent, BigInteger m)`
`byte[]`	`toByteArray()`	caches

Methods inherited from class java.math.BigInteger

abs, add, and, andNot, bitCount, bitLength, byteValueExact, clearBit, compareTo, divide, divideAndRemainder, doubleValue, flipBit, floatValue, gcd, getLowestSetBit, intValue, intValueExact, isProbablePrime, longValue, longValueExact, max, min, mod, multiply, negate, nextProbablePrime, not, or, pow, probablePrime, remainder, setBit, shiftLeft, shiftRight, shortValueExact, signum, sqrt, sqrtAndRemainder, subtract, testBit, toString, toString, valueOf, xor

Methods inherited from class java.lang.Number

byteValue, shortValue

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Details
- NativeBigInteger
  
  public NativeBigInteger(byte[] val)
- NativeBigInteger
  
  public NativeBigInteger(int signum, byte[] magnitude)
- NativeBigInteger
  
  public NativeBigInteger(int bitlen, int certainty, Random rnd)
- NativeBigInteger
  
  public NativeBigInteger(int numbits, Random rnd)
- NativeBigInteger
  
  public NativeBigInteger(String val)
- NativeBigInteger
  
  public NativeBigInteger(String val, int radix)
- NativeBigInteger
  
  public NativeBigInteger(BigInteger integer)
  
  Creates a new NativeBigInteger with the same value as the supplied BigInteger. Warning!, not very efficent
Method Details
- getJbigiVersion
  
  public static int getJbigiVersion()
  
  Get the jbigi version
  
  Returns:
  
  0 if no jbigi available, 2 if version info not supported
  
  Since:
  
  0.9.26
- getLibGMPVersion
  
  public static String getLibGMPVersion()
  
  Get the libgmp version
  
  Returns:
  
  "unknown" if no jbigi available or if version not supported
  
  Since:
  
  0.9.26
- modPow
  
  public BigInteger modPow(BigInteger exponent, BigInteger m)
  
  Overrides:
  
  modPow in class BigInteger
  
  Parameters:
  
  m - must be postive
  
  exponent - must be postive
  
  Throws:
  
  ArithmeticException - if m <= 0 or exponent <=0
- modPowCT
  
  public BigInteger modPowCT(BigInteger exponent, BigInteger m)
  
  Parameters:
  
  exponent - must be postive
  
  m - must be postive and odd
  
  Throws:
  
  ArithmeticException - if m <= 0 or m is even or exponent <=0
  
  Since:
  
  0.9.26 and libjbigi version 3 and GMP version 5
- modInverse
  
  public BigInteger modInverse(BigInteger m)
  
  Overrides:
  
  modInverse in class BigInteger
  
  Throws:
  
  ArithmeticException - if not coprime with m, or m <= 0
  
  Since:
  
  0.9.26 and libjbigi version 3
- toByteArray
  
  public byte[] toByteArray()
  
  caches
  
  Overrides:
  
  toByteArray in class BigInteger
- isNative
  
  public static boolean isNative()
  
  Returns:
  
  True iff native methods will be used by this class
- loadStatus
  
  public static String loadStatus()
  
  Returns:
  
  A string suitable for display to the user
- getLoadedResourceName
  
  public static String getLoadedResourceName()
  
  The name of the library loaded, if known. Null if unknown or not loaded. Currently non-null only if extracted from jbigi.jar.
  
  Since:
  
  0.9.17
- cpuType
  
  public static String cpuType()
- cpuModel
  
  public static String cpuModel()
- main
  
  public static void main(String[] args)
  
  Compare the BigInteger.modPow vs the NativeBigInteger.modPow of some really big (2Kbit) numbers 100 different times and benchmark the performance.
  
  Parameters:
  
  args - -n Disable native test
- equals
  
  public boolean equals(Object o)
  
  Overrides:
  
  equals in class BigInteger
- hashCode
  
  public int hashCode()
  
  Overrides:
  
  hashCode in class BigInteger

Class NativeBigInteger

Field Summary

Fields inherited from class java.math.BigInteger

Constructor Summary

Method Summary

Methods inherited from class java.math.BigInteger

Methods inherited from class java.lang.Number

Methods inherited from class java.lang.Object

Constructor Details

Method Details