ds.ov2.bignat
Class Fake_rsa_exponent

java.lang.Object
  ds.ov2.bignat.Fake_rsa_exponent

All Implemented Interfaces:

RSA_exponent_interface

public class Fake_rsa_exponent
extends Object
implements RSA_exponent_interface

RSA_exponent_interface implementation for the host. Uses BigInteger internally. Provides nothing more than just BigInteger.modPow with a strange interface.

This class makes it possible to use Vector.mont_rsa_exponent_mod and code that depends on it on the host, for instance in a test frame.

As far as possible other code is written in terms of RSA_exponent_interface to avoid cpp trickery. However, when it comes to constructor calls, there is no way around it. For those few places the cpp macro RSA_EXPONENT is used. It expands to either RSA_exponent or to Fake_rsa_exponent.

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

CPP Preprocessing

no cpp preprocessing needed for this class

Execution Environment:

host

Author:

Hendrik Tews

Version:

$Revision: 1.14 $

Last Commit:

$Date: 2009-05-20 14:16:57 $ by $Author: tews $

Field Summary

private BigInteger	exponent The configured exponent.
private BigInteger	modulus The configured modulus.

Constructor Summary

Fake_rsa_exponent()
Non-allocating constructor.

Fake_rsa_exponent(short key_byte_size)
Allocating constructor.

Method Summary

void	allocate(short key_byte_size) Empty method.
void	fixed_power(Bignat base, Bignat result, short offset) Modular power with preconfigured modulus and exponent.
void	init_key(short key_size) Empty method.
void	power(Bignat base, Bignat exp, Bignat result, short offset) Modular exponent.
void	set_exponent(Bignat exponent, Bignat temp, short offset) Saves the exponent exponent for later use in modulus.
void	set_modulus(Bignat mod, short offset) Saves the modulus mod for later use in modulus.

Methods inherited from class java.lang.Object

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

Field Detail

modulus

private BigInteger modulus

The configured modulus. Set in set_modulus.

exponent

private BigInteger exponent

The configured exponent. Set in set_exponent.

Constructor Detail

Fake_rsa_exponent

public Fake_rsa_exponent()

Non-allocating constructor. Empty, because there is nothing to do here.

Fake_rsa_exponent

public Fake_rsa_exponent(short key_byte_size)

Allocating constructor. Calls the non-allocating constructor and allocate as prescribed, although they are all empty.

Parameters:

key_byte_size - ignored argument

Method Detail

init_key

public void init_key(short key_size)

Empty method. Only here to comply with RSA_exponent_interface.

Specified by:

init_key in interface RSA_exponent_interface

Parameters:

key_size - ignored argument

allocate

public void allocate(short key_byte_size)

Empty method. Only here to comply with RSA_exponent_interface.

Specified by:

allocate in interface RSA_exponent_interface

Parameters:

key_byte_size - ignored argument

set_modulus

public void set_modulus(Bignat mod,
                        short offset)

Saves the modulus mod for later use in modulus.

Specified by:

set_modulus in interface RSA_exponent_interface

Parameters:

mod - modulus to use later in exponent

offset - this argument is ignored in this class

set_exponent

public void set_exponent(Bignat exponent,
                         Bignat temp,
                         short offset)

Saves the exponent exponent for later use in modulus.

Specified by:

set_exponent in interface RSA_exponent_interface

Parameters:

exponent - exponent to use later in power or fixed_power

temp - this argument is ignored in this class

offset - this argument is ignored in this class

fixed_power

public void fixed_power(Bignat base,
                        Bignat result,
                        short offset)

Modular power with preconfigured modulus and exponent. Sets result to base^exp mod modulus, where the modulus and exp must have been configured before with set_modulus and set_exponent, respectively.

Specified by:

fixed_power in interface RSA_exponent_interface

Parameters:

base -

result - reference for storing the result

offset - this argument is ignored in this class

power

public void power(Bignat base,
                  Bignat exp,
                  Bignat result,
                  short offset)

Modular exponent. Sets result to base^exp (modulo modulus), where the modulus must have been configured before with set_modulus.

Computations are done with BigInteger, data conversion with Convert_serializable.

Specified by:

power in interface RSA_exponent_interface

Parameters:

base - base

exp - exponent

result - gets the result base^exponent modulo modulus

offset - this argument is ignored in this class