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genopri-shcs/project/PPPCommons/src/test/ECPointCompressionTest.java
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ECPointCompressionTest.java
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package test;
import java.math.BigInteger;
import java.util.LinkedList;
import java.util.Random;
import org.spongycastle.asn1.nist.NISTNamedCurves;
import org.spongycastle.asn1.x9.X9ECParameters;
import org.spongycastle.math.ec.ECCurve;
import org.spongycastle.math.ec.ECPoint;
public class ECPointCompressionTest {
public static void main(String[] args) {
advancedTest(100, "P-384");
advancedTest(100, "K-409");
advancedTest(100, "B-409");
}
@SuppressWarnings("unused")
private static void basicTest(String curveName) {
X9ECParameters ecParams = NISTNamedCurves.getByName("P-384");
ECCurve curve = ecParams.getCurve();
ECPoint g = ecParams.getG();
byte[] gEnc = g.getEncoded();
byte[] gEncComp = g.getEncoded(true);
System.out.println("Length enc = " + gEnc.length);
System.out.println("Length enc comp = " + gEncComp.length);
ECPoint p1 = curve.decodePoint(gEnc);
ECPoint p2 = curve.decodePoint(gEncComp);
if (p1.equals(p2)) {
System.out.println("Equal");
}
else {
System.out.println("Not equal");
}
}
public static void advancedTest(int nbTests, String curveName) {
X9ECParameters ecParams = NISTNamedCurves.getByName(curveName);
ECCurve curve = ecParams.getCurve();
ECPoint g = ecParams.getG();
// generate numbers
LinkedList<BigInteger> numbers = new LinkedList<>();
// numbers.add(BigInteger.ZERO);
numbers.add(BigInteger.ONE);
// numbers.add(ecParams.getN());
Random rand = new Random();
for (int i = 0; i < nbTests; i++) {
numbers.add(new BigInteger(20, rand));
}
int minEnc = 1000000;
int maxEnc = 0;
int minEncComp = 100000;
int maxEncComp = 0;
for (BigInteger n : numbers) {
ECPoint p = g.multiply(n);
byte[] enc = p.getEncoded();
byte[] encComp = p.getEncoded(true);
if (pointCompressionFine(curve, p, enc, encComp)) {
minEnc = (enc.length < minEnc)? enc.length : minEnc;
maxEnc = (enc.length > maxEnc)? enc.length : maxEnc;
minEncComp = (encComp.length < minEncComp)? encComp.length : minEncComp;
maxEncComp = (encComp.length > maxEncComp)? encComp.length : maxEncComp;
}
else {
System.out.println("Points not equal for " + n.toString());
break;
}
}
System.out.println((minEnc == maxEnc) + "; MinEnc=" + minEnc + "; maxEnc=" + maxEnc);
System.out.println((minEncComp == maxEncComp) + "; MinEncComp=" + minEncComp + "; maxEncComp=" + maxEncComp);
}
private static boolean pointCompressionFine(ECCurve curve, ECPoint orig, byte[] enc, byte[] encComp) {
ECPoint p = curve.decodePoint(enc);
ECPoint pComp = curve.decodePoint(encComp);
if (!orig.equals(p)) {
return false;
}
else if (!orig.equals(pComp)) {
return false;
}
return true;
}
}
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