org.bouncycastle.math.ec

Class ECCurve

java.lang.Object

org.bouncycastle.math.ec.ECCurve

Direct Known Subclasses:

ECCurve.AbstractF2m, ECCurve.AbstractFp

public abstract class ECCurve
extends java.lang.Object

base class for an elliptic curve

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ECCurve.AbstractF2m
static class	ECCurve.AbstractFp
class	ECCurve.Config
static class	ECCurve.F2m Elliptic curves over F2m.
static class	ECCurve.Fp Elliptic curve over Fp

Field Summary

Fields

Modifier and Type	Field and Description
protected ECFieldElement	a
protected ECFieldElement	b
protected java.math.BigInteger	cofactor
protected int	coord
static int	COORD_AFFINE
static int	COORD_HOMOGENEOUS
static int	COORD_JACOBIAN
static int	COORD_JACOBIAN_CHUDNOVSKY
static int	COORD_JACOBIAN_MODIFIED
static int	COORD_LAMBDA_AFFINE
static int	COORD_LAMBDA_PROJECTIVE
static int	COORD_SKEWED
protected ECEndomorphism	endomorphism
protected FiniteField	field
protected ECMultiplier	multiplier
protected java.math.BigInteger	order

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ECCurve(FiniteField field)

Method Summary

Modifier and Type	Method and Description
protected void	checkPoint(ECPoint point)
protected void	checkPoints(ECPoint[] points)
protected void	checkPoints(ECPoint[] points, int off, int len)
protected abstract ECCurve	cloneCurve()
ECCurve.Config	configure()
ECLookupTable	createCacheSafeLookupTable(ECPoint[] points, int off, int len) Create a cache-safe lookup table for the specified sequence of points.
protected ECMultiplier	createDefaultMultiplier()
ECPoint	createPoint(java.math.BigInteger x, java.math.BigInteger y)
protected abstract ECPoint	createRawPoint(ECFieldElement x, ECFieldElement y)
protected abstract ECPoint	createRawPoint(ECFieldElement x, ECFieldElement y, ECFieldElement[] zs)
ECPoint	decodePoint(byte[] encoded) Decode a point on this curve from its ASN.1 encoding.
protected abstract ECPoint	decompressPoint(int yTilde, java.math.BigInteger X1)
boolean	equals(ECCurve other)
boolean	equals(java.lang.Object obj)
abstract ECFieldElement	fromBigInteger(java.math.BigInteger x)
ECFieldElement	getA()
int	getAffinePointEncodingLength(boolean compressed)
static int[]	getAllCoordinateSystems()
ECFieldElement	getB()
java.math.BigInteger	getCofactor()
int	getCoordinateSystem()
ECEndomorphism	getEndomorphism()
FiniteField	getField()
int	getFieldElementEncodingLength()
abstract int	getFieldSize()
abstract ECPoint	getInfinity()
ECMultiplier	getMultiplier() Sets the default ECMultiplier, unless already set.
java.math.BigInteger	getOrder()
PreCompInfo	getPreCompInfo(ECPoint point, java.lang.String name)
int	hashCode()
ECPoint	importPoint(ECPoint p)
abstract boolean	isValidFieldElement(java.math.BigInteger x)
void	normalizeAll(ECPoint[] points) 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.
void	normalizeAll(ECPoint[] points, int off, int len, ECFieldElement iso) 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.
PreCompInfo	precompute(ECPoint point, java.lang.String name, PreCompCallback callback) Compute a PreCompInfo for a point on this curve, under a given name.
abstract ECFieldElement	randomFieldElement(java.security.SecureRandom r)
abstract ECFieldElement	randomFieldElementMult(java.security.SecureRandom r)
boolean	supportsCoordinateSystem(int coord)
ECPoint	validatePoint(java.math.BigInteger x, java.math.BigInteger y)

Methods inherited from class java.lang.Object

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

Field Detail

COORD_AFFINE

public static final int COORD_AFFINE

See Also:

Constant Field Values

COORD_HOMOGENEOUS

public static final int COORD_HOMOGENEOUS

See Also:

Constant Field Values

COORD_JACOBIAN

public static final int COORD_JACOBIAN

See Also:

Constant Field Values

COORD_JACOBIAN_CHUDNOVSKY

public static final int COORD_JACOBIAN_CHUDNOVSKY

See Also:

Constant Field Values

COORD_JACOBIAN_MODIFIED

public static final int COORD_JACOBIAN_MODIFIED

See Also:

Constant Field Values

COORD_LAMBDA_AFFINE

public static final int COORD_LAMBDA_AFFINE

See Also:

Constant Field Values

COORD_LAMBDA_PROJECTIVE

public static final int COORD_LAMBDA_PROJECTIVE

See Also:

Constant Field Values

COORD_SKEWED

public static final int COORD_SKEWED

See Also:

Constant Field Values

field

protected FiniteField field

a

protected ECFieldElement a

b

protected ECFieldElement b

order

protected java.math.BigInteger order

cofactor

protected java.math.BigInteger cofactor

coord

protected int coord

endomorphism

protected ECEndomorphism endomorphism

multiplier

protected ECMultiplier multiplier

Constructor Detail

ECCurve

protected ECCurve(FiniteField field)

Method Detail

getAllCoordinateSystems

public static int[] getAllCoordinateSystems()

getFieldSize

public abstract int getFieldSize()

fromBigInteger

public abstract ECFieldElement fromBigInteger(java.math.BigInteger x)

isValidFieldElement

public abstract boolean isValidFieldElement(java.math.BigInteger x)

randomFieldElement

public abstract ECFieldElement randomFieldElement(java.security.SecureRandom r)

randomFieldElementMult

public abstract ECFieldElement randomFieldElementMult(java.security.SecureRandom r)

configure

public ECCurve.Config configure()

getFieldElementEncodingLength

public int getFieldElementEncodingLength()

getAffinePointEncodingLength

public int getAffinePointEncodingLength(boolean compressed)

validatePoint

public ECPoint validatePoint(java.math.BigInteger x,
                             java.math.BigInteger y)

createPoint

public ECPoint createPoint(java.math.BigInteger x,
                           java.math.BigInteger y)

cloneCurve

protected abstract ECCurve cloneCurve()

createRawPoint

protected abstract ECPoint createRawPoint(ECFieldElement x,
                                          ECFieldElement y)

createRawPoint

protected abstract ECPoint createRawPoint(ECFieldElement x,
                                          ECFieldElement y,
                                          ECFieldElement[] zs)

createDefaultMultiplier

protected ECMultiplier createDefaultMultiplier()

supportsCoordinateSystem

public boolean supportsCoordinateSystem(int coord)

getPreCompInfo

public PreCompInfo getPreCompInfo(ECPoint point,
                                  java.lang.String name)

precompute

public PreCompInfo precompute(ECPoint point,
                              java.lang.String name,
                              PreCompCallback callback)

Compute a PreCompInfo for a point on this curve, under a given name. Used by ECMultipliers to save the precomputation for this ECPoint for use by subsequent multiplication.

Parameters:

point - The ECPoint to store precomputations for.

name - A String used to index precomputations of different types.

callback - Called to calculate the PreCompInfo.

importPoint

public ECPoint importPoint(ECPoint p)

normalizeAll

public void normalizeAll(ECPoint[] points)

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. Where more than one point is to be normalized, this method will generally be more efficient than normalizing each point separately.

Parameters:

points - An array of points that will be updated in place with their normalized versions, where necessary

normalizeAll

public void normalizeAll(ECPoint[] points,
                         int off,
                         int len,
                         ECFieldElement iso)

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. Where more than one point is to be normalized, this method will generally be more efficient than normalizing each point separately. An (optional) z-scaling factor can be applied; effectively each z coordinate is scaled by this value prior to normalization (but only one actual multiplication is needed).

Parameters:

points - An array of points that will be updated in place with their normalized versions, where necessary

off - The start of the range of points to normalize

len - The length of the range of points to normalize

iso - The (optional) z-scaling factor - can be null

getInfinity

public abstract ECPoint getInfinity()

getField

public FiniteField getField()

getA

public ECFieldElement getA()

getB

public ECFieldElement getB()

getOrder

public java.math.BigInteger getOrder()

getCofactor

public java.math.BigInteger getCofactor()

getCoordinateSystem

public int getCoordinateSystem()

decompressPoint

protected abstract ECPoint decompressPoint(int yTilde,
                                           java.math.BigInteger X1)

getEndomorphism

public ECEndomorphism getEndomorphism()

getMultiplier

public ECMultiplier getMultiplier()

Sets the default ECMultiplier, unless already set. We avoid synchronizing for performance reasons, so there is no uniqueness guarantee.

decodePoint

public ECPoint decodePoint(byte[] encoded)

Decode a point on this curve from its ASN.1 encoding. The different encodings are taken account of, including point compression for Fp (X9.62 s 4.2.1 pg 17).

Returns:

The decoded point.

createCacheSafeLookupTable

public ECLookupTable createCacheSafeLookupTable(ECPoint[] points,
                                                int off,
                                                int len)

Create a cache-safe lookup table for the specified sequence of points. All the points MUST belong to this ECCurve instance, and MUST already be normalized.

checkPoint

protected void checkPoint(ECPoint point)

checkPoints

protected void checkPoints(ECPoint[] points)

checkPoints

protected void checkPoints(ECPoint[] points,
                           int off,
                           int len)

equals

public boolean equals(ECCurve other)

equals

public boolean equals(java.lang.Object obj)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object