Add custom curve for secp224k1

1 files changed, 150 insertions, 0 deletions

diff --git a/crypto/src/math/ec/custom/sec/SecP224K1Field.cs b/crypto/src/math/ec/custom/sec/SecP224K1Field.cs
new file mode 100644
index 000000000..edc938d22
--- /dev/null
+++ b/crypto/src/math/ec/custom/sec/SecP224K1Field.cs
@@ -0,0 +1,150 @@
+using System;
+using System.Diagnostics;
+
+namespace Org.BouncyCastle.Math.EC.Custom.Sec
+{
+    internal class SecP224K1Field
+    {
+        // 2^224 - 2^32 - 2^12 - 2^11 - 2^9 - 2^7 - 2^4 - 2 - 1
+        internal static readonly uint[] P = new uint[]{ 0xFFFFE56D, 0xFFFFFFFE, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF,
+            0xFFFFFFFF };
+        private const uint P6 = 0xFFFFFFFF;
+        private static readonly uint[] PExt = new uint[]{ 0x02C23069, 0x00003526, 0x00000001, 0x00000000, 0x00000000,
+            0x00000000, 0x00000000, 0xFFFFCADA, 0xFFFFFFFD, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF };
+        private const uint PExt13 = 0xFFFFFFFF;
+        private const ulong PInv = 0x0000000100001A93L; 
+        private const uint PInv33 = 0x1A93;
+
+        public static void Add(uint[] x, uint[] y, uint[] z)
+        {
+            uint c = Nat224.Add(x, y, z);
+            if (c != 0 || (z[6] == P6 && Nat224.Gte(z, P)))
+            {
+                Nat224.AddDWord(PInv, z, 0);
+            }
+        }
+
+        public static void AddExt(uint[] xx, uint[] yy, uint[] zz)
+        {
+            uint c = Nat224.AddExt(xx, yy, zz);
+            if (c != 0 || (zz[13] == PExt13 && Nat224.GteExt(zz, PExt)))
+            {
+                Nat224.SubExt(zz, PExt, zz);
+            }
+        }
+
+        public static void AddOne(uint[] x, uint[] z)
+        {
+            Array.Copy(x, 0, z, 0, 8);
+            uint c = Nat224.Inc(z, 0);
+            if (c != 0 || (z[6] == P6 && Nat224.Gte(z, P)))
+            {
+                Nat224.AddDWord(PInv, z, 0);
+            }
+        }
+
+        public static uint[] FromBigInteger(BigInteger x)
+        {
+            uint[] z = Nat224.FromBigInteger(x);
+            if (z[6] == P6 && Nat224.Gte(z, P))
+            {
+                Nat224.AddDWord(PInv, z, 0);
+            }
+            return z;
+        }
+
+        public static void Half(uint[] x, uint[] z)
+        {
+            if ((x[0] & 1) == 0)
+            {
+                Nat224.ShiftDownBit(x, 0, z);
+            }
+            else
+            {
+                uint c = Nat224.Add(x, P, z);
+                Nat224.ShiftDownBit(z, c, z);
+            }
+        }
+
+        public static void Multiply(uint[] x, uint[] y, uint[] z)
+        {
+            uint[] tt = Nat224.CreateExt();
+            Nat224.Mul(x, y, tt);
+            Reduce(tt, z);
+        }
+
+        public static void Negate(uint[] x, uint[] z)
+        {
+            if (Nat224.IsZero(x))
+            {
+                Nat224.Zero(z);
+            }
+            else
+            {
+                Nat224.Sub(P, x, z);
+            }
+        }
+
+        public static void Reduce(uint[] xx, uint[] z)
+        {
+            ulong c = Nat224.Mul33Add(PInv33, xx, 7, xx, 0, z, 0);
+            c = Nat224.Mul33DWordAdd(PInv33, c, z, 0);
+
+            Debug.Assert(c == 0 || c == 1);
+
+            if (c != 0 || (z[6] == P6 && Nat224.Gte(z, P)))
+            {
+                Nat224.AddDWord(PInv, z, 0);
+            }
+        }
+
+        public static void Square(uint[] x, uint[] z)
+        {
+            uint[] tt = Nat224.CreateExt();
+            Nat224.Square(x, tt);
+            Reduce(tt, z);
+        }
+
+        public static void SquareN(uint[] x, int n, uint[] z)
+        {
+            Debug.Assert(n > 0);
+
+            uint[] tt = Nat224.CreateExt();
+            Nat224.Square(x, tt);
+            Reduce(tt, z);
+
+            while (--n > 0)
+            {
+                Nat224.Square(z, tt);
+                Reduce(tt, z);
+            }
+        }
+
+        public static void Subtract(uint[] x, uint[] y, uint[] z)
+        {
+            int c = Nat224.Sub(x, y, z);
+            if (c != 0)
+            {
+                Nat224.SubDWord(PInv, z);
+            }
+        }
+
+        public static void SubtractExt(uint[] xx, uint[] yy, uint[] zz)
+        {
+            int c = Nat224.SubExt(xx, yy, zz);
+            if (c != 0)
+            {
+                Nat224.AddExt(zz, PExt, zz);
+            }
+        }
+
+        public static void Twice(uint[] x, uint[] z)
+        {
+            uint c = Nat224.ShiftUpBit(x, 0, z);
+            if (c != 0 || (z[6] == P6 && Nat224.Gte(z, P)))
+            {
+                Nat224.AddDWord(PInv, z, 0);
+            }
+        }
+    }
+}