iaik.security.ec.math.curve

Class ECDSAMultiplySimultaneouslyAndCompareHelper

java.lang.Object

iaik.security.ec.math.curve.ECDSAMultiplySimultaneouslyAndCompareHelper

public final class ECDSAMultiplySimultaneouslyAndCompareHelper
extends Object

Helper class for simultaneous multiplication and comparison of the X coordinate as used in ECDSA. Note that this class only serves as helper class to provide an improved version of the ECDSA verification algorithm. While this class is public due to technical reasons, it is not considered part of the public interface and hence may change without further notice.

Author:

Sebastian Ramacher

Constructor Summary

Constructors

Constructor and Description
ECDSAMultiplySimultaneouslyAndCompareHelper(EllipticCurve curve) Create new instance.

Method Summary

Modifier and Type	Method and Description
boolean	multiplyAndCompare(BigInteger k, BigInteger l, BigInteger r) Perform simultaneous multiplication to compute k * g + l * q and check if the x coordinate of result equals r modulo the curve order.
void	precomputeFirstPoint(ECPoint q) Compute precomputation data for the first base point.
void	precomputeSecondPoint(ECPoint q) Compute precomputation data for the second base point.

Methods inherited from class java.lang.Object

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

Constructor Detail

ECDSAMultiplySimultaneouslyAndCompareHelper

public ECDSAMultiplySimultaneouslyAndCompareHelper(EllipticCurve curve)

Create new instance.

Parameters:

curve - the curve

Method Detail

multiplyAndCompare

public boolean multiplyAndCompare(BigInteger k,
                                  BigInteger l,
                                  BigInteger r)

Perform simultaneous multiplication to compute k * g + l * q and check if the x coordinate of result equals r modulo the curve order.

Parameters:

k - scalar for the generator

l - scalar for the second generator

r - expected x coordinate

Returns:

whether the x coordinate of the result equals r

precomputeFirstPoint

public void precomputeFirstPoint(ECPoint q)

Compute precomputation data for the first base point. This functions needs to be called before calling multiplyAndCompare(BigInteger, BigInteger, BigInteger) for the first time.

Parameters:

q - second point

precomputeSecondPoint

public void precomputeSecondPoint(ECPoint q)

Compute precomputation data for the second base point. This functions needs to be called before calling multiplyAndCompare(BigInteger, BigInteger, BigInteger) for the first time.

Parameters:

q - second point