1 files changed, 157 insertions, 0 deletions
diff --git a/crypto/src/math/ec/custom/sec/SecP256K1FieldElement.cs b/crypto/src/math/ec/custom/sec/SecP256K1FieldElement.cs
new file mode 100644
index 000000000..4da1013d1
--- /dev/null
+++ b/crypto/src/math/ec/custom/sec/SecP256K1FieldElement.cs
@@ -0,0 +1,157 @@
+using System;
+using System.Diagnostics;
+
+using Org.BouncyCastle.Utilities;
+
+namespace Org.BouncyCastle.Math.EC.Custom.Sec
+{
+    internal class SecP256K1FieldElement
+        : ECFieldElement
+    {
+        public static readonly BigInteger Q = SecP256K1Curve.q;
+
+        protected internal readonly uint[] x;
+
+        public SecP256K1FieldElement(BigInteger x)
+        {
+            if (x == null || x.SignValue < 0 || x.CompareTo(Q) >= 0)
+                throw new ArgumentException("value invalid for SecP256K1FieldElement", "x");
+
+            this.x = SecP256K1Field.FromBigInteger(x);
+        }
+
+        public SecP256K1FieldElement()
+        {
+            this.x = Nat256.Create();
+        }
+
+        protected internal SecP256K1FieldElement(uint[] x)
+        {
+            this.x = x;
+        }
+
+        public override bool IsZero
+        {
+            get { return Nat256.IsZero(x); }
+        }
+
+        public override bool IsOne
+        {
+            get { return Nat256.IsOne(x); }
+        }
+
+        public override bool TestBitZero()
+        {
+            return Nat256.GetBit(x, 0) == 1;
+        }
+
+        public override BigInteger ToBigInteger()
+        {
+            return Nat256.ToBigInteger(x);
+        }
+
+        public override string FieldName
+        {
+            get { return "SecP256K1Field"; }
+        }
+
+        public override int FieldSize
+        {
+            get { return Q.BitLength; }
+        }
+
+        public override ECFieldElement Add(ECFieldElement b)
+        {
+            uint[] z = Nat256.Create();
+            SecP256K1Field.Add(x, ((SecP256K1FieldElement)b).x, z);
+            return new SecP256K1FieldElement(z);
+        }
+
+        public override ECFieldElement AddOne()
+        {
+            uint[] z = Nat256.Create();
+            SecP256K1Field.AddOne(x, z);
+            return new SecP256K1FieldElement(z);
+        }
+
+        public override ECFieldElement Subtract(ECFieldElement b)
+        {
+            uint[] z = Nat256.Create();
+            SecP256K1Field.Subtract(x, ((SecP256K1FieldElement)b).x, z);
+            return new SecP256K1FieldElement(z);
+        }
+
+        public override ECFieldElement Multiply(ECFieldElement b)
+        {
+            uint[] z = Nat256.Create();
+            SecP256K1Field.Multiply(x, ((SecP256K1FieldElement)b).x, z);
+            return new SecP256K1FieldElement(z);
+        }
+
+        public override ECFieldElement Divide(ECFieldElement b)
+        {
+    //        return Multiply(b.Invert());
+            uint[] z = Nat256.Create();
+            Mod.Invert(SecP256K1Field.P, ((SecP256K1FieldElement)b).x, z);
+            SecP256K1Field.Multiply(z, x, z);
+            return new SecP256K1FieldElement(z);
+        }
+
+        public override ECFieldElement Negate()
+        {
+            uint[] z = Nat256.Create();
+            SecP256K1Field.Negate(x, z);
+            return new SecP256K1FieldElement(z);
+        }
+
+        public override ECFieldElement Square()
+        {
+            uint[] z = Nat256.Create();
+            SecP256K1Field.Square(x, z);
+            return new SecP256K1FieldElement(z);
+        }
+
+        public override ECFieldElement Invert()
+        {
+    //        return new SecP256K1FieldElement(ToBigInteger().ModInverse(Q));
+            uint[] z = Nat256.Create();
+            Mod.Invert(SecP256K1Field.P, x, z);
+            return new SecP256K1FieldElement(z);
+        }
+
+        // D.1.4 91
+        /**
+         * return a sqrt root - the routine verifies that the calculation returns the right value - if
+         * none exists it returns null.
+         */
+        public override ECFieldElement Sqrt()
+        {
+            ECFieldElement root = new FpFieldElement(Q, ToBigInteger()).Sqrt();
+            return root == null ? null : new SecP256K1FieldElement(root.ToBigInteger());
+        }
+
+        public override bool Equals(object obj)
+        {
+            return Equals(obj as SecP256K1FieldElement);
+        }
+
+        public override bool Equals(ECFieldElement other)
+        {
+            return Equals(other as SecP256K1FieldElement);
+        }
+
+        public virtual bool Equals(SecP256K1FieldElement other)
+        {
+            if (this == other)
+                return true;
+            if (null == other)
+                return false;
+            return Arrays.AreEqual(x, other.x);
+        }
+
+        public override int GetHashCode()
+        {
+            return Q.GetHashCode() ^ Arrays.GetHashCode(x);
+        }
+    }
+}