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Diffstat (limited to 'libraries/spongycastle/core/src/test/java/org/spongycastle/math/ec/test/ECPointTest.java')
| -rw-r--r-- | libraries/spongycastle/core/src/test/java/org/spongycastle/math/ec/test/ECPointTest.java | 455 |
1 files changed, 455 insertions, 0 deletions
diff --git a/libraries/spongycastle/core/src/test/java/org/spongycastle/math/ec/test/ECPointTest.java b/libraries/spongycastle/core/src/test/java/org/spongycastle/math/ec/test/ECPointTest.java new file mode 100644 index 000000000..a14e062d0 --- /dev/null +++ b/libraries/spongycastle/core/src/test/java/org/spongycastle/math/ec/test/ECPointTest.java @@ -0,0 +1,455 @@ +package org.spongycastle.math.ec.test; + +import java.math.BigInteger; +import java.security.SecureRandom; +import java.util.Enumeration; + +import junit.framework.Test; +import junit.framework.TestCase; +import junit.framework.TestSuite; + +import org.spongycastle.asn1.sec.SECNamedCurves; +import org.spongycastle.asn1.x9.X9ECParameters; +import org.spongycastle.math.ec.ECCurve; +import org.spongycastle.math.ec.ECPoint; + +/** + * Test class for {@link org.spongycastle.math.ec.ECPoint ECPoint}. All + * literature values are taken from "Guide to elliptic curve cryptography", + * Darrel Hankerson, Alfred J. Menezes, Scott Vanstone, 2004, Springer-Verlag + * New York, Inc. + */ +public class ECPointTest extends TestCase +{ + /** + * Random source used to generate random points + */ + private SecureRandom secRand = new SecureRandom(); + + private ECPointTest.Fp fp = null; + + private ECPointTest.F2m f2m = null; + + /** + * Nested class containing sample literature values for <code>Fp</code>. + */ + public static class Fp + { + private final BigInteger q = new BigInteger("29"); + + private final BigInteger a = new BigInteger("4"); + + private final BigInteger b = new BigInteger("20"); + + private final ECCurve curve = new ECCurve.Fp(q, a, b); + + private final ECPoint infinity = curve.getInfinity(); + + private final int[] pointSource = { 5, 22, 16, 27, 13, 6, 14, 6 }; + + private ECPoint[] p = new ECPoint[pointSource.length / 2]; + + /** + * Creates the points on the curve with literature values. + */ + private void createPoints() + { + for (int i = 0; i < pointSource.length / 2; i++) + { + p[i] = curve.createPoint( + new BigInteger(Integer.toString(pointSource[2 * i])), + new BigInteger(Integer.toString(pointSource[2 * i + 1]))); + } + } + } + + /** + * Nested class containing sample literature values for <code>F2m</code>. + */ + public static class F2m + { + // Irreducible polynomial for TPB z^4 + z + 1 + private final int m = 4; + + private final int k1 = 1; + + // a = z^3 + private final BigInteger aTpb = new BigInteger("1000", 2); + + // b = z^3 + 1 + private final BigInteger bTpb = new BigInteger("1001", 2); + + private final ECCurve.F2m curve = new ECCurve.F2m(m, k1, aTpb, bTpb); + + private final ECPoint.F2m infinity = (ECPoint.F2m) curve.getInfinity(); + + private final String[] pointSource = { "0010", "1111", "1100", "1100", + "0001", "0001", "1011", "0010" }; + + private ECPoint[] p = new ECPoint[pointSource.length / 2]; + + /** + * Creates the points on the curve with literature values. + */ + private void createPoints() + { + for (int i = 0; i < pointSource.length / 2; i++) + { + p[i] = curve.createPoint( + new BigInteger(pointSource[2 * i], 2), + new BigInteger(pointSource[2 * i + 1], 2)); + } + } + } + + public void setUp() + { + fp = new ECPointTest.Fp(); + fp.createPoints(); + + f2m = new ECPointTest.F2m(); + f2m.createPoints(); + } + + /** + * Tests, if inconsistent points can be created, i.e. points with exactly + * one null coordinate (not permitted). + */ + public void testPointCreationConsistency() + { + try + { + ECPoint bad = fp.curve.createPoint(new BigInteger("12"), null); + fail(); + } + catch (IllegalArgumentException expected) + { + } + + try + { + ECPoint bad = fp.curve.createPoint(null, new BigInteger("12")); + fail(); + } + catch (IllegalArgumentException expected) + { + } + + try + { + ECPoint bad = f2m.curve.createPoint(new BigInteger("1011"), null); + fail(); + } + catch (IllegalArgumentException expected) + { + } + + try + { + ECPoint bad = f2m.curve.createPoint(null, new BigInteger("1011")); + fail(); + } + catch (IllegalArgumentException expected) + { + } + } + + /** + * Tests <code>ECPoint.add()</code> against literature values. + * + * @param p + * The array of literature values. + * @param infinity + * The point at infinity on the respective curve. + */ + private void implTestAdd(ECPoint[] p, ECPoint infinity) + { + assertPointsEqual("p0 plus p1 does not equal p2", p[2], p[0].add(p[1])); + assertPointsEqual("p1 plus p0 does not equal p2", p[2], p[1].add(p[0])); + for (int i = 0; i < p.length; i++) + { + assertPointsEqual("Adding infinity failed", p[i], p[i].add(infinity)); + assertPointsEqual("Adding to infinity failed", p[i], infinity.add(p[i])); + } + } + + /** + * Calls <code>implTestAdd()</code> for <code>Fp</code> and + * <code>F2m</code>. + */ + public void testAdd() + { + implTestAdd(fp.p, fp.infinity); + implTestAdd(f2m.p, f2m.infinity); + } + + /** + * Tests <code>ECPoint.twice()</code> against literature values. + * + * @param p + * The array of literature values. + */ + private void implTestTwice(ECPoint[] p) + { + assertPointsEqual("Twice incorrect", p[3], p[0].twice()); + assertPointsEqual("Add same point incorrect", p[3], p[0].add(p[0])); + } + + /** + * Calls <code>implTestTwice()</code> for <code>Fp</code> and + * <code>F2m</code>. + */ + public void testTwice() + { + implTestTwice(fp.p); + implTestTwice(f2m.p); + } + + private void implTestThreeTimes(ECPoint[] p) + { + ECPoint P = p[0]; + ECPoint _3P = P.add(P).add(P); + assertPointsEqual("ThreeTimes incorrect", _3P, P.threeTimes()); + assertPointsEqual("TwicePlus incorrect", _3P, P.twicePlus(P)); + } + + /** + * Calls <code>implTestThreeTimes()</code> for <code>Fp</code> and + * <code>F2m</code>. + */ + public void testThreeTimes() + { + implTestThreeTimes(fp.p); + implTestThreeTimes(f2m.p); + } + + /** + * Goes through all points on an elliptic curve and checks, if adding a + * point <code>k</code>-times is the same as multiplying the point by + * <code>k</code>, for all <code>k</code>. Should be called for points + * on very small elliptic curves only. + * + * @param p + * The base point on the elliptic curve. + * @param infinity + * The point at infinity on the elliptic curve. + */ + private void implTestAllPoints(ECPoint p, ECPoint infinity) + { + ECPoint adder = infinity; + ECPoint multiplier = infinity; + + BigInteger i = BigInteger.valueOf(1); + do + { + adder = adder.add(p); + multiplier = p.multiply(i); + assertPointsEqual("Results of add() and multiply() are inconsistent " + + i, adder, multiplier); + i = i.add(BigInteger.ONE); + } + while (!(adder.equals(infinity))); + } + + /** + * Calls <code>implTestAllPoints()</code> for the small literature curves, + * both for <code>Fp</code> and <code>F2m</code>. + */ + public void testAllPoints() + { + for (int i = 0; i < fp.p.length; i++) + { + implTestAllPoints(fp.p[0], fp.infinity); + } + + for (int i = 0; i < f2m.p.length; i++) + { + implTestAllPoints(f2m.p[0], f2m.infinity); + } + } + + /** + * Simple shift-and-add multiplication. Serves as reference implementation + * to verify (possibly faster) implementations in + * {@link org.spongycastle.math.ec.ECPoint ECPoint}. + * + * @param p + * The point to multiply. + * @param k + * The multiplier. + * @return The result of the point multiplication <code>kP</code>. + */ + private ECPoint multiply(ECPoint p, BigInteger k) + { + ECPoint q = p.getCurve().getInfinity(); + int t = k.bitLength(); + for (int i = 0; i < t; i++) + { + if (i != 0) + { + p = p.twice(); + } + if (k.testBit(i)) + { + q = q.add(p); + } + } + return q; + } + + /** + * Checks, if the point multiplication algorithm of the given point yields + * the same result as point multiplication done by the reference + * implementation given in <code>multiply()</code>. This method chooses a + * random number by which the given point <code>p</code> is multiplied. + * + * @param p + * The point to be multiplied. + * @param numBits + * The bitlength of the random number by which <code>p</code> + * is multiplied. + */ + private void implTestMultiply(ECPoint p, int numBits) + { + BigInteger k = new BigInteger(numBits, secRand); + ECPoint ref = multiply(p, k); + ECPoint q = p.multiply(k); + assertPointsEqual("ECPoint.multiply is incorrect", ref, q); + } + + /** + * Checks, if the point multiplication algorithm of the given point yields + * the same result as point multiplication done by the reference + * implementation given in <code>multiply()</code>. This method tests + * multiplication of <code>p</code> by every number of bitlength + * <code>numBits</code> or less. + * + * @param p + * The point to be multiplied. + * @param numBits + * Try every multiplier up to this bitlength + */ + private void implTestMultiplyAll(ECPoint p, int numBits) + { + BigInteger bound = BigInteger.ONE.shiftLeft(numBits); + BigInteger k = BigInteger.ZERO; + + do + { + ECPoint ref = multiply(p, k); + ECPoint q = p.multiply(k); + assertPointsEqual("ECPoint.multiply is incorrect", ref, q); + k = k.add(BigInteger.ONE); + } + while (k.compareTo(bound) < 0); + } + + /** + * Tests <code>ECPoint.add()</code> and <code>ECPoint.subtract()</code> + * for the given point and the given point at infinity. + * + * @param p + * The point on which the tests are performed. + * @param infinity + * The point at infinity on the same curve as <code>p</code>. + */ + private void implTestAddSubtract(ECPoint p, ECPoint infinity) + { + assertPointsEqual("Twice and Add inconsistent", p.twice(), p.add(p)); + assertPointsEqual("Twice p - p is not p", p, p.twice().subtract(p)); + assertPointsEqual("TwicePlus(p, -p) is not p", p, p.twicePlus(p.negate())); + assertPointsEqual("p - p is not infinity", infinity, p.subtract(p)); + assertPointsEqual("p plus infinity is not p", p, p.add(infinity)); + assertPointsEqual("infinity plus p is not p", p, infinity.add(p)); + assertPointsEqual("infinity plus infinity is not infinity ", infinity, infinity.add(infinity)); + assertPointsEqual("Twice infinity is not infinity ", infinity, infinity.twice()); + } + + /** + * Calls <code>implTestAddSubtract()</code> for literature values, both + * for <code>Fp</code> and <code>F2m</code>. + */ + public void testAddSubtractMultiplySimple() + { + for (int iFp = 0; iFp < fp.pointSource.length / 2; iFp++) + { + implTestAddSubtract(fp.p[iFp], fp.infinity); + + // Could be any numBits, 6 is chosen at will + implTestMultiplyAll(fp.p[iFp], 6); + implTestMultiplyAll(fp.infinity, 6); + } + + for (int iF2m = 0; iF2m < f2m.pointSource.length / 2; iF2m++) + { + implTestAddSubtract(f2m.p[iF2m], f2m.infinity); + + // Could be any numBits, 6 is chosen at will + implTestMultiplyAll(f2m.p[iF2m], 6); + implTestMultiplyAll(f2m.infinity, 6); + } + } + + /** + * Test encoding with and without point compression. + * + * @param p + * The point to be encoded and decoded. + */ + private void implTestEncoding(ECPoint p) + { + // Not Point Compression + ECPoint unCompP = p.getCurve().createPoint(p.getAffineXCoord().toBigInteger(), p.getAffineYCoord().toBigInteger(), false); + + // Point compression + ECPoint compP = p.getCurve().createPoint(p.getAffineXCoord().toBigInteger(), p.getAffineYCoord().toBigInteger(), true); + + byte[] unCompBarr = unCompP.getEncoded(); + ECPoint decUnComp = p.getCurve().decodePoint(unCompBarr); + assertPointsEqual("Error decoding uncompressed point", p, decUnComp); + + byte[] compBarr = compP.getEncoded(); + ECPoint decComp = p.getCurve().decodePoint(compBarr); + assertPointsEqual("Error decoding compressed point", p, decComp); + } + + /** + * Calls <code>implTestAddSubtract()</code>, + * <code>implTestMultiply</code> and <code>implTestEncoding</code> for + * the standard elliptic curves as given in <code>SECNamedCurves</code>. + */ + public void testAddSubtractMultiplyTwiceEncoding() + { + Enumeration curveEnum = SECNamedCurves.getNames(); + while (curveEnum.hasMoreElements()) + { + String name = (String) curveEnum.nextElement(); + X9ECParameters x9ECParameters = SECNamedCurves.getByName(name); + + BigInteger n = x9ECParameters.getN(); + + // The generator is multiplied by random b to get random q + BigInteger b = new BigInteger(n.bitLength(), secRand); + ECPoint g = x9ECParameters.getG(); + ECPoint q = g.multiply(b).normalize(); + + // Get point at infinity on the curve + ECPoint infinity = x9ECParameters.getCurve().getInfinity(); + + implTestAddSubtract(q, infinity); + implTestMultiply(q, n.bitLength()); + implTestMultiply(infinity, n.bitLength()); + implTestEncoding(q); + } + } + + private void assertPointsEqual(String message, ECPoint a, ECPoint b) + { + assertEquals(message, a, b); + } + + public static Test suite() + { + return new TestSuite(ECPointTest.class); + } +} |