org.bouncycastle.math.ec
Class ECPoint

java.lang.Object
  |
  +--org.bouncycastle.math.ec.ECPoint

Direct Known Subclasses:

ECPoint.AbstractF2m, ECPoint.AbstractFp

public abstract class ECPoint

extends java.lang.Object

base class for points on elliptic curves.

Inner Class Summary

static class	ECPoint.AbstractF2m
static class	ECPoint.AbstractFp
static class	ECPoint.F2m Elliptic curve points over F2m
static class	ECPoint.Fp Elliptic curve points over Fp

Field Summary

protected ECCurve	curve
protected static ECFieldElement[]	EMPTY_ZS
protected java.util.Hashtable	preCompTable
protected ECFieldElement	x
protected ECFieldElement	y
protected ECFieldElement[]	zs

Constructor Summary

protected	ECPoint(ECCurve curve, ECFieldElement x, ECFieldElement y)
protected	ECPoint(ECCurve curve, ECFieldElement x, ECFieldElement y, ECFieldElement[] zs)

Method Summary

abstract ECPoint	add(ECPoint b)
protected void	checkNormalized()
protected ECPoint	createScaledPoint(ECFieldElement sx, ECFieldElement sy)
protected abstract ECPoint	detach()
void	encodeTo(boolean compressed, byte[] buf, int off)
boolean	equals(ECPoint other)
boolean	equals(java.lang.Object other)
ECFieldElement	getAffineXCoord() Returns the affine x-coordinate after checking that this point is normalized.
ECFieldElement	getAffineYCoord() Returns the affine y-coordinate after checking that this point is normalized
protected abstract boolean	getCompressionYTilde()
ECCurve	getCurve()
protected int	getCurveCoordinateSystem()
ECPoint	getDetachedPoint()
byte[]	getEncoded(boolean compressed) Get an encoding of the point value, optionally in compressed format.
int	getEncodedLength(boolean compressed)
protected static ECFieldElement[]	getInitialZCoords(ECCurve curve)
ECFieldElement	getRawXCoord()
ECFieldElement	getRawYCoord()
protected ECFieldElement[]	getRawZCoords()
ECFieldElement	getXCoord() Returns the x-coordinate.
ECFieldElement	getYCoord() Returns the y-coordinate.
ECFieldElement	getZCoord(int index)
ECFieldElement[]	getZCoords()
int	hashCode()
boolean	isInfinity()
boolean	isNormalized()
boolean	isValid()
ECPoint	multiply(java.math.BigInteger k) Multiplies this ECPoint by the given number.
abstract ECPoint	negate()
ECPoint	normalize() Normalization ensures that any projective coordinate is 1, and therefore that the x, y coordinates reflect those of the equivalent point in an affine coordinate system.
protected abstract boolean	satisfiesCurveEquation()
protected boolean	satisfiesOrder()
ECPoint	scaleX(ECFieldElement scale)
ECPoint	scaleXNegateY(ECFieldElement scale)
ECPoint	scaleY(ECFieldElement scale)
ECPoint	scaleYNegateX(ECFieldElement scale)
abstract ECPoint	subtract(ECPoint b)
ECPoint	threeTimes()
ECPoint	timesPow2(int e)
java.lang.String	toString()
abstract ECPoint	twice()
ECPoint	twicePlus(ECPoint b)

Methods inherited from class java.lang.Object

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

Field Detail

EMPTY_ZS

protected static final ECFieldElement[] EMPTY_ZS

curve

protected ECCurve curve

x

protected ECFieldElement x

y

protected ECFieldElement y

zs

protected ECFieldElement[] zs

preCompTable

protected java.util.Hashtable preCompTable

Constructor Detail

ECPoint

protected ECPoint(ECCurve curve,
                  ECFieldElement x,
                  ECFieldElement y)

ECPoint

protected ECPoint(ECCurve curve,
                  ECFieldElement x,
                  ECFieldElement y,
                  ECFieldElement[] zs)

Method Detail

getInitialZCoords

protected static ECFieldElement[] getInitialZCoords(ECCurve curve)

satisfiesCurveEquation

protected abstract boolean satisfiesCurveEquation()

satisfiesOrder

protected boolean satisfiesOrder()

getDetachedPoint

public final ECPoint getDetachedPoint()

getCurve

public ECCurve getCurve()

detach

protected abstract ECPoint detach()

getCurveCoordinateSystem

protected int getCurveCoordinateSystem()

getAffineXCoord

public ECFieldElement getAffineXCoord()

Returns the affine x-coordinate after checking that this point is normalized.

Returns:

The affine x-coordinate of this point

Throws:

java.lang.IllegalStateException - if the point is not normalized

getAffineYCoord

public ECFieldElement getAffineYCoord()

Returns the affine y-coordinate after checking that this point is normalized

Returns:

The affine y-coordinate of this point

Throws:

java.lang.IllegalStateException - if the point is not normalized

getXCoord

public ECFieldElement getXCoord()

Returns the x-coordinate. Caution: depending on the curve's coordinate system, this may not be the same value as in an affine coordinate system; use normalize() to get a point where the coordinates have their affine values, or use getAffineXCoord() if you expect the point to already have been normalized.

Returns:

the x-coordinate of this point

getYCoord

public ECFieldElement getYCoord()

Returns the y-coordinate. Caution: depending on the curve's coordinate system, this may not be the same value as in an affine coordinate system; use normalize() to get a point where the coordinates have their affine values, or use getAffineYCoord() if you expect the point to already have been normalized.

Returns:

the y-coordinate of this point

getZCoord

public ECFieldElement getZCoord(int index)

getZCoords

public ECFieldElement[] getZCoords()

getRawXCoord

public final ECFieldElement getRawXCoord()

getRawYCoord

public final ECFieldElement getRawYCoord()

getRawZCoords

protected final ECFieldElement[] getRawZCoords()

checkNormalized

protected void checkNormalized()

isNormalized

public boolean isNormalized()

normalize

public ECPoint normalize()

Normalization ensures that any projective coordinate is 1, and therefore that the x, y coordinates reflect those of the equivalent point in an affine coordinate system.

Returns:

a new ECPoint instance representing the same point, but with normalized coordinates

createScaledPoint

protected ECPoint createScaledPoint(ECFieldElement sx,
                                    ECFieldElement sy)

isInfinity

public boolean isInfinity()

isValid

public boolean isValid()

scaleX

public ECPoint scaleX(ECFieldElement scale)

scaleXNegateY

public ECPoint scaleXNegateY(ECFieldElement scale)

scaleY

public ECPoint scaleY(ECFieldElement scale)

scaleYNegateX

public ECPoint scaleYNegateX(ECFieldElement scale)

equals

public boolean equals(ECPoint other)

equals

public boolean equals(java.lang.Object other)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

getEncoded

public byte[] getEncoded(boolean compressed)

Get an encoding of the point value, optionally in compressed format.

Parameters:

compressed - whether to generate a compressed point encoding.

Returns:

the point encoding

getEncodedLength

public int getEncodedLength(boolean compressed)

encodeTo

public void encodeTo(boolean compressed,
                     byte[] buf,
                     int off)

getCompressionYTilde

protected abstract boolean getCompressionYTilde()

add

public abstract ECPoint add(ECPoint b)

negate

public abstract ECPoint negate()

subtract

public abstract ECPoint subtract(ECPoint b)

timesPow2

public ECPoint timesPow2(int e)

twice

public abstract ECPoint twice()

twicePlus

public ECPoint twicePlus(ECPoint b)

threeTimes

public ECPoint threeTimes()

multiply

public ECPoint multiply(java.math.BigInteger k)

Multiplies this ECPoint by the given number.

Parameters:

k - The multiplicator.

Returns:

k * this.