public X9ECParameters(
Asn1Sequence seq)
{
if (!(seq[0] is DerInteger) ||
!((DerInteger)seq[0]).Value.Equals(BigInteger.One))
{
throw new ArgumentException("bad version in X9ECParameters");
}
this.n = ((DerInteger)seq[4]).Value;
if (seq.Count == 6)
{
this.h = ((DerInteger)seq[5]).Value;
}
X9Curve x9c = new X9Curve(
X9FieldID.GetInstance(seq[1]), n, h,
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.seed = x9c.GetSeed();
}
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");
}
}
public X9Curve(
X9FieldID fieldID,
BigInteger order,
BigInteger cofactor,
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 p = ((DerInteger)fieldID.Parameters).Value;
BigInteger A = new BigInteger(1, Asn1OctetString.GetInstance(seq[0]).GetOctets());
BigInteger B = new BigInteger(1, Asn1OctetString.GetInstance(seq[1]).GetOctets());
curve = new FpCurve(p, A, B, order, cofactor);
}
else if (fieldIdentifier.Equals(X9ObjectIdentifiers.CharacteristicTwoField))
{
// Characteristic two field
DerSequence parameters = (DerSequence)fieldID.Parameters;
int m = ((DerInteger)parameters[0]).IntValueExact;
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]).IntValueExact;
}
else
{
// Pentanomial basis representation
DerSequence pentanomial = (DerSequence)parameters[2];
k1 = ((DerInteger)pentanomial[0]).IntValueExact;
k2 = ((DerInteger)pentanomial[1]).IntValueExact;
k3 = ((DerInteger)pentanomial[2]).IntValueExact;
}
BigInteger A = new BigInteger(1, Asn1OctetString.GetInstance(seq[0]).GetOctets());
BigInteger B = new BigInteger(1, Asn1OctetString.GetInstance(seq[1]).GetOctets());
curve = new F2mCurve(m, k1, k2, k3, A, B, order, cofactor);
}
else
{
throw new ArgumentException("This type of ECCurve is not implemented");
}
if (seq.Count == 3)
{
seed = ((DerBitString)seq[2]).GetBytes();
}
}
public X9Curve(
X9FieldID fieldID,
Asn1Sequence seq)
: this(fieldID, null, null, seq)
{
}
