diff --git a/crypto/src/math/ec/custom/sec/SecT193R2Curve.cs b/crypto/src/math/ec/custom/sec/SecT193R2Curve.cs
new file mode 100644
index 000000000..b5345730c
--- /dev/null
+++ b/crypto/src/math/ec/custom/sec/SecT193R2Curve.cs
@@ -0,0 +1,190 @@
+using System;
+
+using Org.BouncyCastle.Utilities.Encoders;
+
+namespace Org.BouncyCastle.Math.EC.Custom.Sec
+{
+ internal class SecT193R2Curve
+ : AbstractF2mCurve
+ {
+ private const int SecT193R2_DEFAULT_COORDS = COORD_LAMBDA_PROJECTIVE;
+
+ protected readonly SecT193R2Point m_infinity;
+
+ public SecT193R2Curve()
+ : base(193, 15, 0, 0)
+ {
+ this.m_infinity = new SecT193R2Point(this, null, null);
+
+ this.m_a = FromBigInteger(new BigInteger(1, Hex.Decode("0163F35A5137C2CE3EA6ED8667190B0BC43ECD69977702709B")));
+ this.m_b = FromBigInteger(new BigInteger(1, Hex.Decode("00C9BB9E8927D4D64C377E2AB2856A5B16E3EFB7F61D4316AE")));
+ this.m_order = new BigInteger(1, Hex.Decode("010000000000000000000000015AAB561B005413CCD4EE99D5"));
+ this.m_cofactor = BigInteger.Two;
+
+ this.m_coord = SecT193R2_DEFAULT_COORDS;
+ }
+
+ protected override ECCurve CloneCurve()
+ {
+ return new SecT193R2Curve();
+ }
+
+ public override bool SupportsCoordinateSystem(int coord)
+ {
+ switch (coord)
+ {
+ case COORD_LAMBDA_PROJECTIVE:
+ return true;
+ default:
+ return false;
+ }
+ }
+
+ public override ECPoint Infinity
+ {
+ get { return m_infinity; }
+ }
+
+ public override int FieldSize
+ {
+ get { return 193; }
+ }
+
+ public override ECFieldElement FromBigInteger(BigInteger x)
+ {
+ return new SecT193FieldElement(x);
+ }
+
+ protected internal override ECPoint CreateRawPoint(ECFieldElement x, ECFieldElement y, bool withCompression)
+ {
+ return new SecT193R2Point(this, x, y, withCompression);
+ }
+
+ protected internal override ECPoint CreateRawPoint(ECFieldElement x, ECFieldElement y, ECFieldElement[] zs, bool withCompression)
+ {
+ return new SecT193R2Point(this, x, y, zs, withCompression);
+ }
+
+ public override bool IsKoblitz
+ {
+ get { return false; }
+ }
+
+ /**
+ * Decompresses a compressed point P = (xp, yp) (X9.62 s 4.2.2).
+ *
+ * @param yTilde
+ * ~yp, an indication bit for the decompression of yp.
+ * @param X1
+ * The field element xp.
+ * @return the decompressed point.
+ */
+ protected override ECPoint DecompressPoint(int yTilde, BigInteger X1)
+ {
+ ECFieldElement x = FromBigInteger(X1), y = null;
+ if (x.IsZero)
+ {
+ y = B.Sqrt();
+ }
+ else
+ {
+ ECFieldElement beta = x.Square().Invert().Multiply(B).Add(A).Add(x);
+ ECFieldElement z = SolveQuadraticEquation(beta);
+ if (z != null)
+ {
+ if (z.TestBitZero() != (yTilde == 1))
+ {
+ z = z.AddOne();
+ }
+
+ switch (this.CoordinateSystem)
+ {
+ case COORD_LAMBDA_AFFINE:
+ case COORD_LAMBDA_PROJECTIVE:
+ {
+ y = z.Add(x);
+ break;
+ }
+ default:
+ {
+ y = z.Multiply(x);
+ break;
+ }
+ }
+ }
+ }
+
+ if (y == null)
+ throw new ArgumentException("Invalid point compression");
+
+ return this.CreateRawPoint(x, y, true);
+ }
+
+ /**
+ * Solves a quadratic equation <code>z<sup>2</sup> + z = beta</code>(X9.62
+ * D.1.6) The other solution is <code>z + 1</code>.
+ *
+ * @param beta
+ * The value to solve the quadratic equation for.
+ * @return the solution for <code>z<sup>2</sup> + z = beta</code> or
+ * <code>null</code> if no solution exists.
+ */
+ private ECFieldElement SolveQuadraticEquation(ECFieldElement beta)
+ {
+ if (beta.IsZero)
+ {
+ return beta;
+ }
+
+ ECFieldElement zeroElement = FromBigInteger(BigInteger.Zero);
+
+ ECFieldElement z = null;
+ ECFieldElement gamma = null;
+
+ Random rand = new Random();
+ do
+ {
+ ECFieldElement t = FromBigInteger(new BigInteger(193, rand));
+ z = zeroElement;
+ ECFieldElement w = beta;
+ for (int i = 1; i < 193; i++)
+ {
+ ECFieldElement w2 = w.Square();
+ z = z.Square().Add(w2.Multiply(t));
+ w = w2.Add(beta);
+ }
+ if (!w.IsZero)
+ return null;
+ gamma = z.Square().Add(z);
+ }
+ while (gamma.IsZero);
+
+ return z;
+ }
+
+ public virtual int M
+ {
+ get { return 193; }
+ }
+
+ public virtual bool IsTrinomial
+ {
+ get { return true; }
+ }
+
+ public virtual int K1
+ {
+ get { return 15; }
+ }
+
+ public virtual int K2
+ {
+ get { return 0; }
+ }
+
+ public virtual int K3
+ {
+ get { return 0; }
+ }
+ }
+}
|
