Package org.bouncycastle.crypto.hash2curve.impl

Class BLS12_381G1CurveProcessor

java.lang.Object

org.bouncycastle.crypto.hash2curve.impl.BLS12_381G1CurveProcessor

All Implemented Interfaces:

CurveProcessor

public class BLS12_381G1CurveProcessor
extends java.lang.Object
implements CurveProcessor

CurveProcessor for the BLS12381G1_XMD:SHA-256_SSWU_RO_ hash-to-curve suite. Cofactor clearing is done by scalar-multiplication by BLS12_381G1.H_EFF (Bowe's fast cofactor clear), as mandated by RFC 9380 sec. 8.8.1.

Constructor Summary

Constructors

Constructor	Description
BLS12_381G1CurveProcessor()

Method Summary

Modifier and Type	Method	Description
ECPoint	add(ECPoint p, ECPoint q)	Add two points in the curve group.
ECPoint	clearCofactor(ECPoint ecPoint)	Clears the cofactor from the given elliptic curve point.
AffineXY	mapToAffineXY(ECPoint p)	Converts an elliptic-curve point into the affine (x, y) coordinate representation defined by the hash-to-curve suite.

Methods inherited from class java.lang.Object

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

Constructor Detail

BLS12_381G1CurveProcessor

public BLS12_381G1CurveProcessor()

Method Detail

add

public ECPoint add(ECPoint p,
                   ECPoint q)

Description copied from interface: CurveProcessor

Add two points in the curve group. Semantics are curve-model specific.

Specified by:

add in interface CurveProcessor

clearCofactor

public ECPoint clearCofactor(ECPoint ecPoint)

Description copied from interface: CurveProcessor

Clears the cofactor from the given elliptic curve point.

Specified by:

clearCofactor in interface CurveProcessor

Parameters:

ecPoint - the elliptic curve point to process

Returns:

the elliptic curve point with the cofactor cleared

mapToAffineXY

public AffineXY mapToAffineXY(ECPoint p)

Description copied from interface: CurveProcessor

Converts an elliptic-curve point into the affine (x, y) coordinate representation defined by the hash-to-curve suite.

The returned coordinates are intended for serialization, testing, and interoperability with the reference outputs defined in RFC 9380. For most Weierstrass curves, this is simply the affine (x, y) coordinates of the given point. For curves that use a different coordinate model in the specification (e.g. Montgomery curves such as curve25519), this method applies the appropriate coordinate transformation.

This method does not change the underlying group element represented by the point. It only changes how that point is expressed as field elements. The input point is expected to be a valid point on the curve used by the implementation.

Specified by:

mapToAffineXY in interface CurveProcessor

Parameters:

p - a valid elliptic-curve point

Returns:

the affine (x, y) coordinates corresponding to the suite-specific representation of the given point