ds.ov2.bignat
Class Inverse_mod_256

java.lang.Object
  ds.ov2.bignat.Inverse_mod_256

 class Inverse_mod_256
extends Object

Modular inverse modulo 256 for Java Card (currently unused). Can be used to compute Modulus.last_digit_inverse on the Card. Currently unused, because the last_digit_inverse is much more conviniently computed in Host_modulus.

Static class.

For a number of general topics see also the package description.

CPP Preprocessing

This class uses the following cpp defines: PACKAGE, ASSERT, ASSERT_TAG(condition, tag)

Execution Environment:

currently not used

Author:

Hendrik Tews

Version:

$Revision: 1.11 $

Last Commit:

$Date: 2009-03-26 15:51:28 $ by $Author: tews $

Constructor Summary

protected

Inverse_mod_256() Static class, object construction disabled.

Method Summary

static short

get_inverse(short n) Modular inverse modulo 256.

Methods inherited from class java.lang.Object

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

Constructor Detail

Inverse_mod_256

protected Inverse_mod_256()

Static class, object construction disabled.

Method Detail

get_inverse

public static short get_inverse(short n)

Modular inverse modulo 256. Computes x such that x * n == 1 (modulo 256). Uses the iterative method of the extended eucledian algorithm.

The inverse does only exists for odd arguments.

Parameters:

n - n

Returns:

the inverse of n modulo 256