eccurve.java

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// Decompiled by Jad v1.5.8e2. Copyright 2001 Pavel Kouznetsov.
// Jad home page: http://kpdus.tripod.com/jad.html
// Decompiler options: packimports(3) fieldsfirst ansi space 
// Source File Name:   ECCurve.java

package org.bouncycastle.math.ec;

import java.math.BigInteger;
import java.util.Random;

// Referenced classes of package org.bouncycastle.math.ec:
//			ECFieldElement, ECPoint, ECConstants, Tnaf

public abstract class ECCurve
{
	public static class F2m extends ECCurve
	{

		private int m;
		private int k1;
		private int k2;
		private int k3;
		private BigInteger n;
		private BigInteger h;
		private ECPoint.F2m infinity;
		private byte mu;
		private BigInteger si[];

		public int getFieldSize()
		{
			return m;
		}

		public ECFieldElement fromBigInteger(BigInteger x)
		{
			return new ECFieldElement.F2m(m, k1, k2, k3, x);
		}

		public ECPoint createPoint(BigInteger x, BigInteger y, boolean withCompression)
		{
			return new ECPoint.F2m(this, fromBigInteger(x), fromBigInteger(y), withCompression);
		}

		public ECPoint decodePoint(byte encoded[])
		{
			ECPoint p = null;
			switch (encoded[0])
			{
			case 0: // '\0'
				p = getInfinity();
				break;

			case 2: // '\002'
			case 3: // '\003'
				byte enc[] = new byte[encoded.length - 1];
				System.arraycopy(encoded, 1, enc, 0, enc.length);
				if (encoded[0] == 2)
					p = decompressPoint(enc, 0);
				else
					p = decompressPoint(enc, 1);
				break;

			case 4: // '\004'
			case 6: // '\006'
			case 7: // '\007'
				byte xEnc[] = new byte[(encoded.length - 1) / 2];
				byte yEnc[] = new byte[(encoded.length - 1) / 2];
				System.arraycopy(encoded, 1, xEnc, 0, xEnc.length);
				System.arraycopy(encoded, xEnc.length + 1, yEnc, 0, yEnc.length);
				p = new ECPoint.F2m(this, new ECFieldElement.F2m(m, k1, k2, k3, new BigInteger(1, xEnc)), new ECFieldElement.F2m(m, k1, k2, k3, new BigInteger(1, yEnc)), false);
				break;

			case 1: // '\001'
			case 5: // '\005'
			default:
				throw new RuntimeException((new StringBuilder()).append("Invalid point encoding 0x").append(Integer.toString(encoded[0], 16)).toString());
			}
			return p;
		}

		public ECPoint getInfinity()
		{
			return infinity;
		}

		public boolean isKoblitz()
		{
			return n != null && h != null && (a.toBigInteger().equals(ECConstants.ZERO) || a.toBigInteger().equals(ECConstants.ONE)) && b.toBigInteger().equals(ECConstants.ONE);
		}

		synchronized byte getMu()
		{
			if (mu == 0)
				mu = Tnaf.getMu(this);
			return mu;
		}

		synchronized BigInteger[] getSi()
		{
			if (si == null)
				si = Tnaf.getSi(this);
			return si;
		}

		private ECPoint decompressPoint(byte xEnc[], int ypBit)
		{
			ECFieldElement xp = new ECFieldElement.F2m(m, k1, k2, k3, new BigInteger(1, xEnc));
			ECFieldElement yp = null;
			if (xp.toBigInteger().equals(ECConstants.ZERO))
			{
				yp = (ECFieldElement.F2m)b;
				for (int i = 0; i < m - 1; i++)
					yp = yp.square();

			} else
			{
				ECFieldElement beta = xp.add(a).add(b.multiply(xp.square().invert()));
				ECFieldElement z = solveQuadradicEquation(beta);
				if (z == null)
					throw new RuntimeException("Invalid point compression");
				int zBit = 0;
				if (z.toBigInteger().testBit(0))
					zBit = 1;
				if (zBit != ypBit)
					z = z.add(new ECFieldElement.F2m(m, k1, k2, k3, ECConstants.ONE));
				yp = xp.multiply(z);
			}
			return new ECPoint.F2m(this, xp, yp);
		}

		private ECFieldElement solveQuadradicEquation(ECFieldElement beta)
		{
			ECFieldElement zeroElement = new ECFieldElement.F2m(m, k1, k2, k3, ECConstants.ZERO);
			if (beta.toBigInteger().equals(ECConstants.ZERO))
				return zeroElement;
			ECFieldElement z = null;
			ECFieldElement gamma = zeroElement;
			Random rand = new Random();
			do
			{
				ECFieldElement t = new ECFieldElement.F2m(m, k1, k2, k3, new BigInteger(m, rand));
				z = zeroElement;
				ECFieldElement w = beta;
				for (int i = 1; i <= m - 1; i++)
				{
					ECFieldElement w2 = w.square();
					z = z.square().add(w2.multiply(t));
					w = w2.add(beta);
				}

				if (!w.toBigInteger().equals(ECConstants.ZERO))
					return null;
				gamma = z.square().add(z);
			} while (gamma.toBigInteger().equals(ECConstants.ZERO));
			return z;
		}

		public boolean equals(Object anObject)
		{
			if (anObject == this)
				return true;
			if (!(anObject instanceof F2m))
			{
				return false;
			} else
			{
				F2m other = (F2m)anObject;
				return m == other.m && k1 == other.k1 && k2 == other.k2 && k3 == other.k3 && a.equals(other.a) && b.equals(other.b);
			}
		}

		public int hashCode()
		{
			return a.hashCode() ^ b.hashCode() ^ m ^ k1 ^ k2 ^ k3;
		}

		public int getM()
		{
			return m;
		}

		public boolean isTrinomial()
		{
			return k2 == 0 && k3 == 0;
		}

		public int getK1()
		{
			return k1;
		}

		public int getK2()
		{
			return k2;
		}

		public int getK3()
		{
			return k3;
		}

		public BigInteger getN()
		{
			return n;
		}

		public BigInteger getH()
		{
			return h;
		}

		public F2m(int m, int k, BigInteger a, BigInteger b)
		{
			this(m, k, 0, 0, a, b, null, null);
		}

		public F2m(int m, int k, BigInteger a, BigInteger b, BigInteger n, BigInteger h)
		{
			this(m, k, 0, 0, a, b, n, h);
		}

		public F2m(int m, int k1, int k2, int k3, BigInteger a, BigInteger b)
		{
			this(m, k1, k2, k3, a, b, null, null);
		}

		public F2m(int m, int k1, int k2, int k3, BigInteger a, BigInteger b, BigInteger n, 
				BigInteger h)
		{
			mu = 0;
			si = null;
			this.m = m;
			this.k1 = k1;
			this.k2 = k2;
			this.k3 = k3;
			this.n = n;
			this.h = h;
			if (k1 == 0)
				throw new IllegalArgumentException("k1 must be > 0");
			if (k2 == 0)
			{
				if (k3 != 0)
					throw new IllegalArgumentException("k3 must be 0 if k2 == 0");
			} else
			{
				if (k2 <= k1)
					throw new IllegalArgumentException("k2 must be > k1");
				if (k3 <= k2)
					throw new IllegalArgumentException("k3 must be > k2");
			}
			this.a = fromBigInteger(a);
			this.b = fromBigInteger(b);
			infinity = new ECPoint.F2m(this, null, null);
		}
	}

	public static class Fp extends ECCurve
	{

		BigInteger q;
		ECPoint.Fp infinity;

		public BigInteger getQ()
		{
			return q;
		}

		public int getFieldSize()
		{
			return q.bitLength();
		}

		public ECFieldElement fromBigInteger(BigInteger x)
		{
			return new ECFieldElement.Fp(q, x);
		}

		public ECPoint createPoint(BigInteger x, BigInteger y, boolean withCompression)
		{
			return new ECPoint.Fp(this, fromBigInteger(x), fromBigInteger(y), withCompression);
		}

		public ECPoint decodePoint(byte encoded[])
		{
			ECPoint p = null;
			switch (encoded[0])
			{
			case 0: // '\0'
				p = getInfinity();
				break;

			case 2: // '\002'
			case 3: // '\003'
				int ytilde = encoded[0] & 1;
				byte i[] = new byte[encoded.length - 1];
				System.arraycopy(encoded, 1, i, 0, i.length);
				ECFieldElement x = new ECFieldElement.Fp(q, new BigInteger(1, i));
				ECFieldElement alpha = x.multiply(x.square().add(a)).add(b);
				ECFieldElement beta = alpha.sqrt();
				if (beta == null)
					throw new RuntimeException("Invalid point compression");
				int bit0 = beta.toBigInteger().testBit(0) ? 1 : 0;
				if (bit0 == ytilde)
					p = new ECPoint.Fp(this, x, beta, true);
				else
					p = new ECPoint.Fp(this, x, new ECFieldElement.Fp(q, q.subtract(beta.toBigInteger())), true);
				break;

			case 4: // '\004'
			case 6: // '\006'
			case 7: // '\007'
				byte xEnc[] = new byte[(encoded.length - 1) / 2];
				byte yEnc[] = new byte[(encoded.length - 1) / 2];
				System.arraycopy(encoded, 1, xEnc, 0, xEnc.length);
				System.arraycopy(encoded, xEnc.length + 1, yEnc, 0, yEnc.length);
				p = new ECPoint.Fp(this, new ECFieldElement.Fp(q, new BigInteger(1, xEnc)), new ECFieldElement.Fp(q, new BigInteger(1, yEnc)));
				break;

			case 1: // '\001'
			case 5: // '\005'
			default:
				throw new RuntimeException((new StringBuilder()).append("Invalid point encoding 0x").append(Integer.toString(encoded[0], 16)).toString());
			}
			return p;
		}

		public ECPoint getInfinity()
		{
			return infinity;
		}

		public boolean equals(Object anObject)
		{
			if (anObject == this)
				return true;
			if (!(anObject instanceof Fp))
			{
				return false;
			} else
			{
				Fp other = (Fp)anObject;
				return q.equals(other.q) && a.equals(other.a) && b.equals(other.b);
			}
		}

		public int hashCode()
		{
			return a.hashCode() ^ b.hashCode() ^ q.hashCode();
		}

		public Fp(BigInteger q, BigInteger a, BigInteger b)
		{
			this.q = q;
			this.a = fromBigInteger(a);
			this.b = fromBigInteger(b);
			infinity = new ECPoint.Fp(this, null, null);
		}
	}


	ECFieldElement a;
	ECFieldElement b;

	public ECCurve()
	{
	}

	public abstract int getFieldSize();

	public abstract ECFieldElement fromBigInteger(BigInteger biginteger);

	public abstract ECPoint createPoint(BigInteger biginteger, BigInteger biginteger1, boolean flag);

	public abstract ECPoint decodePoint(byte abyte0[]);

	public abstract ECPoint getInfinity();

	public ECFieldElement getA()
	{
		return a;
	}

	public ECFieldElement getB()
	{
		return b;
	}
}