1 files changed, 188 insertions, 0 deletions
diff --git a/crypto/src/math/ec/custom/sec/SecT131R1Curve.cs b/crypto/src/math/ec/custom/sec/SecT131R1Curve.cs
new file mode 100644
index 000000000..789e3c0c3
--- /dev/null
+++ b/crypto/src/math/ec/custom/sec/SecT131R1Curve.cs
@@ -0,0 +1,188 @@
+using System;
+
+using Org.BouncyCastle.Utilities.Encoders;
+
+namespace Org.BouncyCastle.Math.EC.Custom.Sec
+{
+    internal class SecT131R1Curve
+        : AbstractF2mCurve
+    {
+        private const int SecT131R1_DEFAULT_COORDS = COORD_LAMBDA_PROJECTIVE;
+
+        protected readonly SecT131R1Point m_infinity;
+
+        public SecT131R1Curve()
+            : base(131, 2, 3, 8)
+        {
+            this.m_infinity = new SecT131R1Point(this, null, null);
+
+            this.m_a = FromBigInteger(new BigInteger(1, Hex.Decode("07A11B09A76B562144418FF3FF8C2570B8")));
+            this.m_b = FromBigInteger(new BigInteger(1, Hex.Decode("0217C05610884B63B9C6C7291678F9D341")));
+            this.m_order = new BigInteger(1, Hex.Decode("0400000000000000023123953A9464B54D"));
+            this.m_cofactor = BigInteger.Two;
+
+            this.m_coord = SecT131R1_DEFAULT_COORDS;
+        }
+
+        protected override ECCurve CloneCurve()
+        {
+            return new SecT131R1Curve();
+        }
+
+        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 131; }
+        }
+
+        public override ECFieldElement FromBigInteger(BigInteger x)
+        {
+            return new SecT131FieldElement(x);
+        }
+
+        protected internal override ECPoint CreateRawPoint(ECFieldElement x, ECFieldElement y, bool withCompression)
+        {
+            return new SecT131R1Point(this, x, y, withCompression);
+        }
+
+        protected internal override ECPoint CreateRawPoint(ECFieldElement x, ECFieldElement y, ECFieldElement[] zs, bool withCompression)
+        {
+            return new SecT131R1Point(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(131, rand));
+                z = zeroElement;
+                ECFieldElement w = beta;
+                for (int i = 1; i < 131; 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 131; }
+        }
+
+        public virtual bool IsTrinomial
+        {
+            get { return false; }
+        }
+
+        public virtual int K1
+        {
+            get { return 2; }
+        }
+
+        public virtual int K2
+        {
+            get { return 3; }
+        }
+
+        public virtual int K3
+        {
+            get { return 8; }
+        }
+    }
+}