1 files changed, 156 insertions, 0 deletions
diff --git a/bcprov/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP521R1Field.java b/bcprov/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP521R1Field.java
new file mode 100644
index 0000000..00f1066
--- /dev/null
+++ b/bcprov/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP521R1Field.java
@@ -0,0 +1,156 @@
+package org.bouncycastle.math.ec.custom.sec;
+
+import java.math.BigInteger;
+
+import org.bouncycastle.math.raw.Nat;
+import org.bouncycastle.math.raw.Nat512;
+
+public class SecP521R1Field
+{
+    // 2^521 - 1
+    static final int[] P = new int[]{ 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF,
+        0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0x1FF };
+    private static final int P16 = 0x1FF;
+
+    public static void add(int[] x, int[] y, int[] z)
+    {
+        int c = Nat.add(16, x, y, z) + x[16] + y[16];
+        if (c > P16 || (c == P16 && Nat.eq(16, z, P)))
+        {
+            c += Nat.inc(16, z);
+            c &= P16;
+        }
+        z[16] = c;
+    }
+
+    public static void addOne(int[] x, int[] z)
+    {
+        int c = Nat.inc(16, x, z) + x[16];
+        if (c > P16 || (c == P16 && Nat.eq(16, z, P)))
+        {
+            c += Nat.inc(16, z);
+            c &= P16;
+        }
+        z[16] = c;
+    }
+
+    public static int[] fromBigInteger(BigInteger x)
+    {
+        int[] z = Nat.fromBigInteger(521, x);
+        if (Nat.eq(17, z, P))
+        {
+            Nat.zero(17, z);
+        }
+        return z;
+    }
+
+    public static void half(int[] x, int[] z)
+    {
+        int x16 = x[16];
+        int c = Nat.shiftDownBit(16, x, x16, z);
+        z[16] = (x16 >>> 1) | (c >>> 23);
+    }
+
+    public static void multiply(int[] x, int[] y, int[] z)
+    {
+        int[] tt = Nat.create(33);
+        implMultiply(x, y, tt);
+        reduce(tt, z);
+    }
+
+    public static void negate(int[] x, int[] z)
+    {
+        if (Nat.isZero(17, x))
+        {
+            Nat.zero(17, z);
+        }
+        else
+        {
+            Nat.sub(17, P, x, z);
+        }
+    }
+
+    public static void reduce(int[] xx, int[] z)
+    {
+//        assert xx[32] >>> 18 == 0;
+
+        int xx32 = xx[32];
+        int c = Nat.shiftDownBits(16, xx, 16, 9, xx32, z, 0) >>> 23;
+        c += xx32 >>> 9;
+        c += Nat.addTo(16, xx, z);
+        if (c > P16 || (c == P16 && Nat.eq(16, z, P)))
+        {
+            c += Nat.inc(16, z);
+            c &= P16;
+        }
+        z[16] = c;
+    }
+
+    public static void reduce23(int[] z)
+    {
+        int z16 = z[16];
+        int c = Nat.addWordTo(16, z16 >>> 9, z) + (z16 & P16);
+        if (c > P16 || (c == P16 && Nat.eq(16, z, P)))
+        {
+            c += Nat.inc(16, z);
+            c &= P16;
+        }
+        z[16] = c;
+    }
+
+    public static void square(int[] x, int[] z)
+    {
+        int[] tt = Nat.create(33);
+        implSquare(x, tt);
+        reduce(tt, z);
+    }
+
+    public static void squareN(int[] x, int n, int[] z)
+    {
+//        assert n > 0;
+
+        int[] tt = Nat.create(33);
+        implSquare(x, tt);
+        reduce(tt, z);
+
+        while (--n > 0)
+        {
+            implSquare(z, tt);
+            reduce(tt, z);
+        }
+    }
+
+    public static void subtract(int[] x, int[] y, int[] z)
+    {
+        int c = Nat.sub(16, x, y, z) + x[16] - y[16];
+        if (c < 0)
+        {
+            c += Nat.dec(16, z);
+            c &= P16;
+        }
+        z[16] = c;
+    }
+
+    public static void twice(int[] x, int[] z)
+    {
+        int x16 = x[16];
+        int c = Nat.shiftUpBit(16, x, x16 << 23, z) | (x16 << 1);
+        z[16] = c & P16;
+    }
+
+    protected static void implMultiply(int[] x, int[] y, int[] zz)
+    {
+        Nat512.mul(x, y, zz);
+
+        int x16 = x[16], y16 = y[16];
+        zz[32] = Nat.mul31BothAdd(16, x16, y, y16, x, zz, 16) + (x16 * y16);
+    }
+
+    protected static void implSquare(int[] x, int[] zz)
+    {
+        Nat512.square(x, zz);
+
+        int x16 = x[16];
+        zz[32] = Nat.mulWordAddTo(16, x16 << 1, x, 0, zz, 16) + (x16 * x16);
+    }
+}