1 files changed, 179 insertions, 0 deletions
diff --git a/bcprov/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP256K1Field.java b/bcprov/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP256K1Field.java
new file mode 100644
index 0000000..c7b4def
--- /dev/null
+++ b/bcprov/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP256K1Field.java
@@ -0,0 +1,179 @@
+package org.bouncycastle.math.ec.custom.sec;
+
+import java.math.BigInteger;
+
+import org.bouncycastle.math.raw.Nat;
+import org.bouncycastle.math.raw.Nat256;
+
+public class SecP256K1Field
+{
+    // 2^256 - 2^32 - 2^9 - 2^8 - 2^7 - 2^6 - 2^4 - 1
+    static final int[] P = new int[]{ 0xFFFFFC2F, 0xFFFFFFFE, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF,
+        0xFFFFFFFF, 0xFFFFFFFF };
+    static final int[] PExt = new int[]{ 0x000E90A1, 0x000007A2, 0x00000001, 0x00000000, 0x00000000,
+        0x00000000, 0x00000000, 0x00000000, 0xFFFFF85E, 0xFFFFFFFD, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF,
+        0xFFFFFFFF, 0xFFFFFFFF };
+    private static final int[] PExtInv = new int[]{ 0xFFF16F5F, 0xFFFFF85D, 0xFFFFFFFE, 0xFFFFFFFF, 0xFFFFFFFF,
+        0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0x000007A1, 0x00000002 };
+    private static final int P7 = 0xFFFFFFFF;
+    private static final int PExt15 = 0xFFFFFFFF;
+    private static final int PInv33 = 0x3D1;
+
+    public static void add(int[] x, int[] y, int[] z)
+    {
+        int c = Nat256.add(x, y, z);
+        if (c != 0 || (z[7] == P7 && Nat256.gte(z, P)))
+        {
+            Nat.add33To(8, PInv33, z);
+        }
+    }
+
+    public static void addExt(int[] xx, int[] yy, int[] zz)
+    {
+        int c = Nat.add(16, xx, yy, zz);
+        if (c != 0 || (zz[15] == PExt15 && Nat.gte(16, zz, PExt)))
+        {
+            if (Nat.addTo(PExtInv.length, PExtInv, zz) != 0)
+            {
+                Nat.incAt(16, zz, PExtInv.length);
+            }
+        }
+    }
+
+    public static void addOne(int[] x, int[] z)
+    {
+        int c = Nat.inc(8, x, z);
+        if (c != 0 || (z[7] == P7 && Nat256.gte(z, P)))
+        {
+            Nat.add33To(8, PInv33, z);
+        }
+    }
+
+    public static int[] fromBigInteger(BigInteger x)
+    {
+        int[] z = Nat256.fromBigInteger(x);
+        if (z[7] == P7 && Nat256.gte(z, P))
+        {
+            Nat256.subFrom(P, z);
+        }
+        return z;
+    }
+
+    public static void half(int[] x, int[] z)
+    {
+        if ((x[0] & 1) == 0)
+        {
+            Nat.shiftDownBit(8, x, 0, z);
+        }
+        else
+        {
+            int c = Nat256.add(x, P, z);
+            Nat.shiftDownBit(8, z, c);
+        }
+    }
+
+    public static void multiply(int[] x, int[] y, int[] z)
+    {
+        int[] tt = Nat256.createExt();
+        Nat256.mul(x, y, tt);
+        reduce(tt, z);
+    }
+
+    public static void multiplyAddToExt(int[] x, int[] y, int[] zz)
+    {
+        int c = Nat256.mulAddTo(x, y, zz);
+        if (c != 0 || (zz[15] == PExt15 && Nat.gte(16, zz, PExt)))
+        {
+            if (Nat.addTo(PExtInv.length, PExtInv, zz) != 0)
+            {
+                Nat.incAt(16, zz, PExtInv.length);
+            }
+        }
+    }
+
+    public static void negate(int[] x, int[] z)
+    {
+        if (Nat256.isZero(x))
+        {
+            Nat256.zero(z);
+        }
+        else
+        {
+            Nat256.sub(P, x, z);
+        }
+    }
+
+    public static void reduce(int[] xx, int[] z)
+    {
+        long cc = Nat256.mul33Add(PInv33, xx, 8, xx, 0, z, 0);
+        int c = Nat256.mul33DWordAdd(PInv33, cc, z, 0);
+
+        // assert c == 0L || c == 1L;
+
+        if (c != 0 || (z[7] == P7 && Nat256.gte(z, P)))
+        {
+            Nat.add33To(8, PInv33, z);
+        }
+    }
+
+    public static void reduce32(int x, int[] z)
+    {
+        if ((x != 0 && Nat256.mul33WordAdd(PInv33, x, z, 0) != 0)
+            || (z[7] == P7 && Nat256.gte(z, P)))
+        {
+            Nat.add33To(8, PInv33, z);
+        }
+    }
+
+    public static void square(int[] x, int[] z)
+    {
+        int[] tt = Nat256.createExt();
+        Nat256.square(x, tt);
+        reduce(tt, z);
+    }
+
+    public static void squareN(int[] x, int n, int[] z)
+    {
+//        assert n > 0;
+
+        int[] tt = Nat256.createExt();
+        Nat256.square(x, tt);
+        reduce(tt, z);
+
+        while (--n > 0)
+        {
+            Nat256.square(z, tt);
+            reduce(tt, z);
+        }
+    }
+
+    public static void subtract(int[] x, int[] y, int[] z)
+    {
+        int c = Nat256.sub(x, y, z);
+        if (c != 0)
+        {
+            Nat.sub33From(8, PInv33, z);
+        }
+    }
+
+    public static void subtractExt(int[] xx, int[] yy, int[] zz)
+    {
+        int c = Nat.sub(16, xx, yy, zz);
+        if (c != 0)
+        {
+            if (Nat.subFrom(PExtInv.length, PExtInv, zz) != 0)
+            {
+                Nat.decAt(16, zz, PExtInv.length);
+            }
+        }
+    }
+
+    public static void twice(int[] x, int[] z)
+    {
+        int c = Nat.shiftUpBit(8, x, 0, z);
+        if (c != 0 || (z[7] == P7 && Nat256.gte(z, P)))
+        {
+            Nat.add33To(8, PInv33, z);
+        }
+    }
+}