Exemple #1
0
        public X9ECParameters(
            Asn1Sequence seq)
        {
            if (!(seq[0] is DerInteger) ||
                !((DerInteger)seq[0]).Value.Equals(BigInteger.One))
            {
                throw new ArgumentException("bad version in X9ECParameters");
            }

            X9Curve x9c = new X9Curve(
                X9FieldID.GetInstance(seq[1]),
                Asn1Sequence.GetInstance(seq[2]));

            this.curve = x9c.Curve;
            object p = seq[3];

            if (p is X9ECPoint)
            {
                this.g = ((X9ECPoint)p);
            }
            else
            {
                this.g = new X9ECPoint(curve, (Asn1OctetString)p);
            }

            this.n    = ((DerInteger)seq[4]).Value;
            this.seed = x9c.GetSeed();

            if (seq.Count == 6)
            {
                this.h = ((DerInteger)seq[5]).Value;
            }
        }
Exemple #2
0
        public X9Curve(
            X9FieldID fieldID,
            Asn1Sequence seq)
        {
            if (fieldID == null)
            {
                throw new ArgumentNullException("fieldID");
            }
            if (seq == null)
            {
                throw new ArgumentNullException("seq");
            }

            this.fieldIdentifier = fieldID.Identifier;

            if (fieldIdentifier.Equals(X9ObjectIdentifiers.PrimeField))
            {
                BigInteger     q   = ((DerInteger)fieldID.Parameters).Value;
                X9FieldElement x9A = new X9FieldElement(q, (Asn1OctetString)seq[0]);
                X9FieldElement x9B = new X9FieldElement(q, (Asn1OctetString)seq[1]);
                curve = new FpCurve(q, x9A.Value.ToBigInteger(), x9B.Value.ToBigInteger());
            }
            else
            {
                if (fieldIdentifier.Equals(X9ObjectIdentifiers.CharacteristicTwoField))
                {
                    // Characteristic two field
                    DerSequence         parameters = (DerSequence)fieldID.Parameters;
                    int                 m          = ((DerInteger)parameters[0]).Value.IntValue;
                    DerObjectIdentifier representation
                        = (DerObjectIdentifier)parameters[1];

                    int k1 = 0;
                    int k2 = 0;
                    int k3 = 0;
                    if (representation.Equals(X9ObjectIdentifiers.TPBasis))
                    {
                        // Trinomial basis representation
                        k1 = ((DerInteger)parameters[2]).Value.IntValue;
                    }
                    else
                    {
                        // Pentanomial basis representation
                        DerSequence pentanomial = (DerSequence)parameters[2];
                        k1 = ((DerInteger)pentanomial[0]).Value.IntValue;
                        k2 = ((DerInteger)pentanomial[1]).Value.IntValue;
                        k3 = ((DerInteger)pentanomial[2]).Value.IntValue;
                    }
                    X9FieldElement x9A = new X9FieldElement(m, k1, k2, k3, (Asn1OctetString)seq[0]);
                    X9FieldElement x9B = new X9FieldElement(m, k1, k2, k3, (Asn1OctetString)seq[1]);
                    // TODO Is it possible to get the order (n) and cofactor(h) too?
                    curve = new F2mCurve(m, k1, k2, k3, x9A.Value.ToBigInteger(), x9B.Value.ToBigInteger());
                }
            }

            if (seq.Count == 3)
            {
                seed = ((DerBitString)seq[2]).GetBytes();
            }
        }
Exemple #3
0
        public X9ECParameters(
            ECCurve curve,
            X9ECPoint g,
            BigInteger n,
            BigInteger h,
            byte[]      seed)
        {
            this.curve = curve;
            this.g     = g;
            this.n     = n;
            this.h     = h;
            this.seed  = seed;

            if (ECAlgorithms.IsFpCurve(curve))
            {
                this.fieldID = new X9FieldID(curve.Field.Characteristic);
            }
            else if (ECAlgorithms.IsF2mCurve(curve))
            {
                IPolynomialExtensionField field = (IPolynomialExtensionField)curve.Field;
                int[] exponents = field.MinimalPolynomial.GetExponentsPresent();
                if (exponents.Length == 3)
                {
                    this.fieldID = new X9FieldID(exponents[2], exponents[1]);
                }
                else if (exponents.Length == 5)
                {
                    this.fieldID = new X9FieldID(exponents[4], exponents[1], exponents[2], exponents[3]);
                }
                else
                {
                    throw new ArgumentException("Only trinomial and pentomial curves are supported");
                }
            }
            else
            {
                throw new ArgumentException("'curve' is of an unsupported type");
            }
        }