1 files changed, 273 insertions, 0 deletions
diff --git a/core/src/main/java/org/spongycastle/math/ec/custom/sec/SecP224R1FieldElement.java b/core/src/main/java/org/spongycastle/math/ec/custom/sec/SecP224R1FieldElement.java
new file mode 100644
index 00000000..3a82fcab
--- /dev/null
+++ b/core/src/main/java/org/spongycastle/math/ec/custom/sec/SecP224R1FieldElement.java
@@ -0,0 +1,273 @@
+package org.spongycastle.math.ec.custom.sec;
+
+import java.math.BigInteger;
+
+import org.spongycastle.math.ec.ECFieldElement;
+import org.spongycastle.math.raw.Mod;
+import org.spongycastle.math.raw.Nat;
+import org.spongycastle.math.raw.Nat224;
+import org.spongycastle.util.Arrays;
+
+public class SecP224R1FieldElement extends ECFieldElement
+{
+    public static final BigInteger Q = SecP224R1Curve.q;
+
+    protected int[] x;
+
+    public SecP224R1FieldElement(BigInteger x)
+    {
+        if (x == null || x.signum() < 0 || x.compareTo(Q) >= 0)
+        {
+            throw new IllegalArgumentException("x value invalid for SecP224R1FieldElement");
+        }
+
+        this.x = SecP224R1Field.fromBigInteger(x);
+    }
+
+    public SecP224R1FieldElement()
+    {
+        this.x = Nat224.create();
+    }
+
+    protected SecP224R1FieldElement(int[] x)
+    {
+        this.x = x;
+    }
+
+    public boolean isZero()
+    {
+        return Nat224.isZero(x);
+    }
+
+    public boolean isOne()
+    {
+        return Nat224.isOne(x);
+    }
+
+    public boolean testBitZero()
+    {
+        return Nat224.getBit(x, 0) == 1;
+    }
+
+    public BigInteger toBigInteger()
+    {
+        return Nat224.toBigInteger(x);
+    }
+
+    public String getFieldName()
+    {
+        return "SecP224R1Field";
+    }
+
+    public int getFieldSize()
+    {
+        return Q.bitLength();
+    }
+
+    public ECFieldElement add(ECFieldElement b)
+    {
+        int[] z = Nat224.create();
+        SecP224R1Field.add(x, ((SecP224R1FieldElement)b).x, z);
+        return new SecP224R1FieldElement(z);
+    }
+
+    public ECFieldElement addOne()
+    {
+        int[] z = Nat224.create();
+        SecP224R1Field.addOne(x, z);
+        return new SecP224R1FieldElement(z);
+    }
+
+    public ECFieldElement subtract(ECFieldElement b)
+    {
+        int[] z = Nat224.create();
+        SecP224R1Field.subtract(x, ((SecP224R1FieldElement)b).x, z);
+        return new SecP224R1FieldElement(z);
+    }
+
+    public ECFieldElement multiply(ECFieldElement b)
+    {
+        int[] z = Nat224.create();
+        SecP224R1Field.multiply(x, ((SecP224R1FieldElement)b).x, z);
+        return new SecP224R1FieldElement(z);
+    }
+
+    public ECFieldElement divide(ECFieldElement b)
+    {
+//        return multiply(b.invert());
+        int[] z = Nat224.create();
+        Mod.invert(SecP224R1Field.P, ((SecP224R1FieldElement)b).x, z);
+        SecP224R1Field.multiply(z, x, z);
+        return new SecP224R1FieldElement(z);
+    }
+
+    public ECFieldElement negate()
+    {
+        int[] z = Nat224.create();
+        SecP224R1Field.negate(x, z);
+        return new SecP224R1FieldElement(z);
+    }
+
+    public ECFieldElement square()
+    {
+        int[] z = Nat224.create();
+        SecP224R1Field.square(x, z);
+        return new SecP224R1FieldElement(z);
+    }
+
+    public ECFieldElement invert()
+    {
+//        return new SecP224R1FieldElement(toBigInteger().modInverse(Q));
+        int[] z = Nat224.create();
+        Mod.invert(SecP224R1Field.P, x, z);
+        return new SecP224R1FieldElement(z);
+    }
+
+    /**
+     * return a sqrt root - the routine verifies that the calculation returns the right value - if
+     * none exists it returns null.
+     */
+    public ECFieldElement sqrt()
+    {
+        int[] c = this.x;
+        if (Nat224.isZero(c) || Nat224.isOne(c))
+        {
+            return this;
+        }
+
+        int[] nc = Nat224.create();
+        SecP224R1Field.negate(c, nc);
+
+        int[] r = Mod.random(SecP224R1Field.P);
+        int[] t = Nat224.create();
+
+        if (!isSquare(c))
+        {
+            return null;
+        }
+
+        while (!trySqrt(nc, r, t))
+        {
+            SecP224R1Field.addOne(r, r);
+        }
+
+        SecP224R1Field.square(t, r);
+
+        return Nat224.eq(c, r) ? new SecP224R1FieldElement(t) : null;
+    }
+
+    public boolean equals(Object other)
+    {
+        if (other == this)
+        {
+            return true;
+        }
+
+        if (!(other instanceof SecP224R1FieldElement))
+        {
+            return false;
+        }
+
+        SecP224R1FieldElement o = (SecP224R1FieldElement)other;
+        return Nat224.eq(x, o.x);
+    }
+
+    public int hashCode()
+    {
+        return Q.hashCode() ^ Arrays.hashCode(x, 0, 7);
+    }
+
+    private static boolean isSquare(int[] x)
+    {
+        int[] t1 = Nat224.create();
+        int[] t2 = Nat224.create();
+        Nat224.copy(x, t1);
+
+        for (int i = 0; i < 7; ++i)
+        {
+            Nat224.copy(t1, t2);
+            SecP224R1Field.squareN(t1, 1 << i, t1);
+            SecP224R1Field.multiply(t1, t2, t1);
+        }
+
+        SecP224R1Field.squareN(t1, 95, t1);
+        return Nat224.isOne(t1);
+    }
+
+    private static void RM(int[] nc, int[] d0, int[] e0, int[] d1, int[] e1, int[] f1, int[] t)
+    {
+        SecP224R1Field.multiply(e1, e0, t);
+        SecP224R1Field.multiply(t, nc, t);
+        SecP224R1Field.multiply(d1, d0, f1);
+        SecP224R1Field.add(f1, t, f1);
+        SecP224R1Field.multiply(d1, e0, t);
+        Nat224.copy(f1, d1);
+        SecP224R1Field.multiply(e1, d0, e1);
+        SecP224R1Field.add(e1, t, e1);
+        SecP224R1Field.square(e1, f1);
+        SecP224R1Field.multiply(f1, nc, f1);
+    }
+
+    private static void RP(int[] nc, int[] d1, int[] e1, int[] f1, int[] t)
+    {
+        Nat224.copy(nc, f1);
+
+        int[] d0 = Nat224.create();
+        int[] e0 = Nat224.create();
+
+        for (int i = 0; i < 7; ++i)
+        {
+            Nat224.copy(d1, d0);
+            Nat224.copy(e1, e0);
+
+            int j = 1 << i;
+            while (--j >= 0)
+            {
+                RS(d1, e1, f1, t);
+            }
+
+            RM(nc, d0, e0, d1, e1, f1, t);
+        }
+    }
+
+    private static void RS(int[] d, int[] e, int[] f, int[] t)
+    {
+        SecP224R1Field.multiply(e, d, e);
+        SecP224R1Field.twice(e, e);
+        SecP224R1Field.square(d, t);
+        SecP224R1Field.add(f, t, d);
+        SecP224R1Field.multiply(f, t, f);
+        int c = Nat.shiftUpBits(7, f, 2, 0);
+        SecP224R1Field.reduce32(c, f);
+    }
+
+    private static boolean trySqrt(int[] nc, int[] r, int[] t)
+    {
+        int[] d1 = Nat224.create();
+        Nat224.copy(r, d1);
+        int[] e1 = Nat224.create();
+        e1[0] = 1;
+        int[] f1 = Nat224.create();
+        RP(nc, d1, e1, f1, t);
+
+        int[] d0 = Nat224.create();
+        int[] e0 = Nat224.create();
+
+        for (int k = 1; k < 96; ++k)
+        {
+            Nat224.copy(d1, d0);
+            Nat224.copy(e1, e0);
+
+            RS(d1, e1, f1, t);
+
+            if (Nat224.isZero(d1))
+            {
+                Mod.invert(SecP224R1Field.P, e0, t);
+                SecP224R1Field.multiply(t, d0, t);
+                return true;
+            }
+        }
+
+        return false;
+    }
+}