using Renci.SshNet.Security.Org.BouncyCastle.Math.Field; using System; namespace Renci.SshNet.Security.Org.BouncyCastle.Math.EC { internal abstract class AbstractFpCurve : ECCurve { protected AbstractFpCurve(BigInteger q) : base(FiniteFields.GetPrimeField(q)) { } public override bool IsValidFieldElement(BigInteger x) { if (x != null && x.SignValue >= 0) return x.CompareTo(Field.Characteristic) < 0; return false; } protected override ECPoint DecompressPoint(int yTilde, BigInteger X1) { ECFieldElement eCFieldElement = FromBigInteger(X1); ECFieldElement eCFieldElement2 = eCFieldElement.Square().Add(A).Multiply(eCFieldElement) .Add(B) .Sqrt(); if (eCFieldElement2 == null) throw new ArgumentException("Invalid point compression"); if (eCFieldElement2.TestBitZero() != (yTilde == 1)) eCFieldElement2 = eCFieldElement2.Negate(); return CreateRawPoint(eCFieldElement, eCFieldElement2, true); } } }