Coverage Summary for Class: BN128G2 (co.rsk.crypto.altbn128java)

Class Class, % Method, % Line, %
BN128G2 0% (0/1) 0% (0/7) 0% (0/15)


1 /* 2  * This file is part of RskJ 3  * Copyright (C) 2019 RSK Labs Ltd. 4  * (derived from ethereumJ library, Copyright (c) 2016 <ether.camp>) 5  * 6  * This program is free software: you can redistribute it and/or modify 7  * it under the terms of the GNU Lesser General Public License as published by 8  * the Free Software Foundation, either version 3 of the License, or 9  * (at your option) any later version. 10  * 11  * This program is distributed in the hope that it will be useful, 12  * but WITHOUT ANY WARRANTY; without even the implied warranty of 13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14  * GNU Lesser General Public License for more details. 15  * 16  * You should have received a copy of the GNU Lesser General Public License 17  * along with this program. If not, see <http://www.gnu.org/licenses/>. 18  */ 19  20 package co.rsk.crypto.altbn128java; 21  22 import java.math.BigInteger; 23  24 import static co.rsk.crypto.altbn128java.Params.R; 25 import static co.rsk.crypto.altbn128java.Params.TWIST_MUL_BY_P_X; 26 import static co.rsk.crypto.altbn128java.Params.TWIST_MUL_BY_P_Y; 27  28 /** 29  * Implementation of specific cyclic subgroup of points belonging to {@link BN128Fp2} <br/> 30  * Members of this subgroup are passed as a second param to pairing input {@link PairingCheck#addPair(BN128G1, BN128G2)} <br/> 31  * <br/> 32  * 33  * The order of subgroup is {@link Params#R} <br/> 34  * Generator of subgroup G = <br/> 35  * (11559732032986387107991004021392285783925812861821192530917403151452391805634 * i + <br/> 36  * 10857046999023057135944570762232829481370756359578518086990519993285655852781, <br/> 37  * 4082367875863433681332203403145435568316851327593401208105741076214120093531 * i + <br/> 38  * 8495653923123431417604973247489272438418190587263600148770280649306958101930) <br/> 39  * <br/> 40  * 41  * @author Mikhail Kalinin 42  * @since 31.08.2017 43  */ 44 public class BN128G2 extends BN128Fp2 { 45  46  BN128G2(BN128<Fp2> p) { 47  super(p.x, p.y, p.z); 48  } 49  50  BN128G2(Fp2 x, Fp2 y, Fp2 z) { 51  super(x, y, z); 52  } 53  54  @Override 55  public BN128G2 toAffine() { 56  return new BN128G2(super.toAffine()); 57  } 58  59  /** 60  * Checks whether provided data are coordinates of a point belonging to subgroup, 61  * if check has been passed it returns a point, otherwise returns null 62  */ 63  public static BN128G2 create(byte[] a, byte[] b, byte[] c, byte[] d) { 64  65  BN128<Fp2> p = BN128Fp2.create(a, b, c, d); 66  67  // fails if point is invalid 68  if (p == null) { 69  return null; 70  } 71  72  // check whether point is a subgroup member 73  if (!isGroupMember(p)) {return null;} 74  75  return new BN128G2(p); 76  } 77  78  private static boolean isGroupMember(BN128<Fp2> p) { 79  BN128<Fp2> left = p.mul(FR_NEG_ONE).add(p); 80  return left.isZero(); // should satisfy condition: -1 * p + p == 0, where -1 belongs to F_r 81  } 82  private static final BigInteger FR_NEG_ONE = BigInteger.ONE.negate().mod(R); 83  84  BN128G2 mulByP() { 85  86  Fp2 rx = TWIST_MUL_BY_P_X.mul(x.frobeniusMap(1)); 87  Fp2 ry = TWIST_MUL_BY_P_Y.mul(y.frobeniusMap(1)); 88  Fp2 rz = z.frobeniusMap(1); 89  90  return new BN128G2(rx, ry, rz); 91  } 92 }