Java EllipticCurve.getField方法代码示例

import java.security.spec.EllipticCurve; //导入方法依赖的package包/类
private static ECCurve convertCurve(
    EllipticCurve ec)
{
    ECField field = ec.getField();
    BigInteger a = ec.getA();
    BigInteger b = ec.getB();

    if (field instanceof ECFieldFp)
    {
        return new ECCurve.Fp(((ECFieldFp)field).getP(), a, b);
    }
    else
    {
        throw new IllegalStateException("not implemented yet!!!");
    }
}
 

import java.security.spec.EllipticCurve; //导入方法依赖的package包/类
public static ECCurve convertCurve(
    EllipticCurve ec)
{
    ECField field = ec.getField();
    BigInteger a = ec.getA();
    BigInteger b = ec.getB();

    if (field instanceof ECFieldFp)
    {
        return new ECCurve.Fp(((ECFieldFp)field).getP(), a, b);
    }
    else
    {
        ECFieldF2m fieldF2m = (ECFieldF2m)field;
        int m = fieldF2m.getM();
        int ks[] = ECUtil.convertMidTerms(fieldF2m.getMidTermsOfReductionPolynomial());
        return new ECCurve.F2m(m, ks[0], ks[1], ks[2], a, b); 
    }
}
 

import java.security.spec.EllipticCurve; //导入方法依赖的package包/类
private static ECParameterSpec mapNonceGMWithECDH(final BigInteger nonceS,
		                                          final ECPoint sharedSecretPointH,
		                                          final ECParameterSpec params) {
	// D~ = (p, a, b, G~, n, h) where G~ = [s]G + H
	final ECPoint generator = params.getGenerator();
	final EllipticCurve curve = params.getCurve();
	final BigInteger a = curve.getA();
	final BigInteger b = curve.getB();
	final ECFieldFp field = (ECFieldFp)curve.getField();
	final BigInteger p = field.getP();
	final BigInteger order = params.getOrder();
	final int cofactor = params.getCofactor();
	final ECPoint ephemeralGenerator = add(multiply(nonceS, generator, params), sharedSecretPointH, params);
	if (!toBouncyCastleECPoint(ephemeralGenerator, params).isValid()) {
		LOGGER.warning("Se ha generado un punto invalido"); //$NON-NLS-1$
	}
	return new ECParameterSpec(new EllipticCurve(new ECFieldFp(p), a, b), ephemeralGenerator, order, cofactor);
}
 

import java.security.spec.EllipticCurve; //导入方法依赖的package包/类
private static ECParameterSpec mapNonceGMWithECDH(final BigInteger nonceS,
		                                          final ECPoint sharedSecretPointH,
		                                          final ECParameterSpec params) {
	// D~ = (p, a, b, G~, n, h) where G~ = [s]G + H
	final ECPoint generator = params.getGenerator();
	final EllipticCurve curve = params.getCurve();
	final BigInteger a = curve.getA();
	final BigInteger b = curve.getB();
	final ECFieldFp field = (ECFieldFp)curve.getField();
	final BigInteger p = field.getP();
	final BigInteger order = params.getOrder();
	final int cofactor = params.getCofactor();
	final ECPoint ephemeralGenerator = add(multiply(nonceS, generator, params), sharedSecretPointH, params);
	if (!toSpongyCastleECPoint(ephemeralGenerator, params).isValid()) {
		LOGGER.warning("Se ha generado un punto invalido"); //$NON-NLS-1$
	}
	return new ECParameterSpec(new EllipticCurve(new ECFieldFp(p), a, b), ephemeralGenerator, order, cofactor);
}
 

import java.security.spec.EllipticCurve; //导入方法依赖的package包/类
/**
 * Decompress a point
 *
 * @param x The x-coordinate of the point
 * @param bit0 true if the least significant bit of y is set.
 * @param ecParams contains the curve of the point. This must be over a prime order field.
 */
public static ECPoint getPoint(BigInteger x, boolean bit0, ECParameterSpec ecParams)
    throws GeneralSecurityException {
  EllipticCurve ec = ecParams.getCurve();
  ECField field = ec.getField();
  if (!(field instanceof ECFieldFp)) {
    throw new GeneralSecurityException("Only curves over prime order fields are supported");
  }
  BigInteger p = ((java.security.spec.ECFieldFp) field).getP();
  if (x.compareTo(BigInteger.ZERO) == -1 || x.compareTo(p) != -1) {
    throw new GeneralSecurityException("x is out of range");
  }
  // Compute rhs == x^3 + a x + b (mod p)
  BigInteger rhs = x.multiply(x).add(ec.getA()).multiply(x).add(ec.getB()).mod(p);
  BigInteger y = modSqrt(rhs, p);
  if (bit0 != y.testBit(0)) {
    y = p.subtract(y).mod(p);
  }
  return new ECPoint(x, y);
}
 

import java.security.spec.EllipticCurve; //导入方法依赖的package包/类
/**
 * Returns a weak public key of order 3 such that the public key point is on the curve specified
 * in ecParams. This method is used to check ECC implementations for missing step in the
 * verification of the public key. E.g. implementations of ECDH must verify that the public key
 * contains a point on the curve as well as public and secret key are using the same curve.
 *
 * @param ecParams the parameters of the key to attack. This must be a curve in Weierstrass form
 *     over a prime order field.
 * @return a weak EC group with a genrator of order 3.
 */
public static ECPublicKeySpec getWeakPublicKey(ECParameterSpec ecParams)
    throws GeneralSecurityException {
  EllipticCurve curve = ecParams.getCurve();
  KeyPairGenerator keyGen = KeyPairGenerator.getInstance("EC");
  keyGen.initialize(ecParams);
  BigInteger p = getModulus(curve);
  BigInteger three = new BigInteger("3");
  while (true) {
    // Generate a point on the original curve
    KeyPair keyPair = keyGen.generateKeyPair();
    ECPublicKey pub = (ECPublicKey) keyPair.getPublic();
    ECPoint w = pub.getW();
    BigInteger x = w.getAffineX();
    BigInteger y = w.getAffineY();
    // Find the curve parameters a,b such that 3*w = infinity.
    // This is the case if the following equations are satisfied:
    //    3x == l^2 (mod p)
    //    l == (3x^2 + a) / 2*y (mod p)
    //    y^2 == x^3 + ax + b (mod p)
    BigInteger l;
    try {
      l = modSqrt(x.multiply(three), p);
    } catch (GeneralSecurityException ex) {
      continue;
    }
    BigInteger xSqr = x.multiply(x).mod(p);
    BigInteger a = l.multiply(y.add(y)).subtract(xSqr.multiply(three)).mod(p);
    BigInteger b = y.multiply(y).subtract(x.multiply(xSqr.add(a))).mod(p);
    EllipticCurve newCurve = new EllipticCurve(curve.getField(), a, b);
    // Just a sanity check.
    checkPointOnCurve(w, newCurve);
    // Cofactor and order are of course wrong.
    ECParameterSpec spec = new ECParameterSpec(newCurve, w, p, 1);
    return new ECPublicKeySpec(w, spec);
  }
}
 

import java.security.spec.EllipticCurve; //导入方法依赖的package包/类
private static ECCurve convertCurve(
    EllipticCurve ec, BigInteger order, int coFactor)
{
    ECField field = ec.getField();
    BigInteger a = ec.getA();
    BigInteger b = ec.getB();

    if (field instanceof ECFieldFp)
    {
        return new ECCurve.Fp(((ECFieldFp)field).getP(), a, b, order, BigInteger.valueOf(coFactor));
    }
    else
    {
        throw new IllegalStateException("not implemented yet!!!");
    }
}
 

import java.security.spec.EllipticCurve; //导入方法依赖的package包/类
public static ECCurve convertCurve(
    EllipticCurve ec)
{
    ECField field = ec.getField();
    BigInteger a = ec.getA();
    BigInteger b = ec.getB();

    if (field instanceof ECFieldFp)
    {
        ECCurve.Fp curve = new ECCurve.Fp(((ECFieldFp)field).getP(), a, b);

        if (customCurves.containsKey(curve))
        {
            return (ECCurve)customCurves.get(curve);
        }

        return curve;
    }
    else
    {
        ECFieldF2m fieldF2m = (ECFieldF2m)field;
        int m = fieldF2m.getM();
        int ks[] = ECUtil.convertMidTerms(fieldF2m.getMidTermsOfReductionPolynomial());
        return new ECCurve.F2m(m, ks[0], ks[1], ks[2], a, b); 
    }
}
 

import java.security.spec.EllipticCurve; //导入方法依赖的package包/类
/**
 * Decode a point on this curve which has been encoded using point
 * compression (X9.62 s 4.2.1 and 4.2.2) or regular encoding.
 * 
 * @param curve
 *            The elliptic curve.
 * @param encoded
 *            The encoded point.
 * @return the decoded point.
 */
public static ECPoint decodePoint(
   EllipticCurve curve, 
   byte[] encoded)
{
    ECCurve c = null;
    
    if (curve.getField() instanceof ECFieldFp)
    {
        c = new ECCurve.Fp(
                ((ECFieldFp)curve.getField()).getP(), curve.getA(), curve.getB());
    }
    else
    {
        int k[] = ((ECFieldF2m)curve.getField()).getMidTermsOfReductionPolynomial();
        
        if (k.length == 3)
        {
            c = new ECCurve.F2m(
                    ((ECFieldF2m)curve.getField()).getM(), k[2], k[1], k[0], curve.getA(), curve.getB());
        }
        else
        {
            c = new ECCurve.F2m(
                    ((ECFieldF2m)curve.getField()).getM(), k[0], curve.getA(), curve.getB());
        }
    }
    
    org.bouncycastle.math.ec.ECPoint p = c.decodePoint(encoded);
    
    return new ECPoint(p.getX().toBigInteger(), p.getY().toBigInteger());
}
 

import java.security.spec.EllipticCurve; //导入方法依赖的package包/类
private static ECCurve toBouncyCastleECCurve(final ECParameterSpec params) {
	final EllipticCurve curve = params.getCurve();
	final ECField field = curve.getField();
	if (!(field instanceof ECFieldFp)) {
		throw new IllegalArgumentException(
			"Solo se soporta 'ECFieldFp' y se proporciono  " + field.getClass().getCanonicalName() //$NON-NLS-1$
		);
	}
	final int coFactor = params.getCofactor();
	final BigInteger order = params.getOrder();
	final BigInteger a = curve.getA();
	final BigInteger b = curve.getB();
	final BigInteger p = getPrime(params);
	return new ECCurve.Fp(p, a, b, order, BigInteger.valueOf(coFactor));
}
 

import java.security.spec.EllipticCurve; //导入方法依赖的package包/类
private static BigInteger getPrime(final ECParameterSpec params) {
	if (params == null) {
		throw new IllegalArgumentException(
			"Los parametros no pueden ser nulos" //$NON-NLS-1$
		);
	}
	final EllipticCurve curve = params.getCurve();
	final ECField field = curve.getField();
	if (!(field instanceof ECFieldFp)) {
		throw new IllegalStateException(
			"Solo se soporta 'ECFieldFp' y se proporciono  " + field.getClass().getCanonicalName() //$NON-NLS-1$
		);
	}
	return ((ECFieldFp)field).getP();
}
 

import java.security.spec.EllipticCurve; //导入方法依赖的package包/类
private static ECCurve toSpongyCastleECCurve(final ECParameterSpec params) {
	final EllipticCurve curve = params.getCurve();
	final ECField field = curve.getField();
	if (!(field instanceof ECFieldFp)) {
		throw new IllegalArgumentException(
			"Solo se soporta 'ECFieldFp' y se proporciono  " + field.getClass().getCanonicalName() //$NON-NLS-1$
		);
	}
	final int coFactor = params.getCofactor();
	final BigInteger order = params.getOrder();
	final BigInteger a = curve.getA();
	final BigInteger b = curve.getB();
	final BigInteger p = getPrime(params);
	return new ECCurve.Fp(p, a, b, order, BigInteger.valueOf(coFactor));
}
 

import java.security.spec.EllipticCurve; //导入方法依赖的package包/类
/**
 * Returns the modulus of the field used by the curve specified in ecParams.
 *
 * @param curve must be a prime order elliptic curve
 * @return the order of the finite field over which curve is defined.
 */
public static BigInteger getModulus(EllipticCurve curve) throws GeneralSecurityException {
  java.security.spec.ECField field = curve.getField();
  if (field instanceof java.security.spec.ECFieldFp) {
    return ((java.security.spec.ECFieldFp) field).getP();
  } else {
    throw new GeneralSecurityException("Only curves over prime order fields are supported");
  }
}
 

import java.security.spec.EllipticCurve; //导入方法依赖的package包/类
/**
 * Decompress a point on an elliptic curve.
 *
 * @param bytes The compressed point. Its representation is z || x where z is 2+lsb(y) and x is
 *     using a unsigned fixed length big-endian representation.
 * @param ecParams the specification of the curve. Only Weierstrass curves over prime order fields
 *     are implemented.
 */
public static ECPoint decompressPoint(byte[] bytes, ECParameterSpec ecParams)
    throws GeneralSecurityException {
  EllipticCurve ec = ecParams.getCurve();
  ECField field = ec.getField();
  if (!(field instanceof ECFieldFp)) {
    throw new GeneralSecurityException("Only curves over prime order fields are supported");
  }
  BigInteger p = ((java.security.spec.ECFieldFp) field).getP();
  int expectedLength = 1 + (p.bitLength() + 7) / 8;
  if (bytes.length != expectedLength) {
    throw new GeneralSecurityException("compressed point has wrong length");
  }
  boolean lsb;
  switch (bytes[0]) {
    case 2:
      lsb = false;
      break;
    case 3:
      lsb = true;
      break;
    default:
      throw new GeneralSecurityException("Invalid format");
  }
  BigInteger x = new BigInteger(1, Arrays.copyOfRange(bytes, 1, bytes.length));
  if (x.compareTo(BigInteger.ZERO) == -1 || x.compareTo(p) != -1) {
    throw new GeneralSecurityException("x is out of range");
  }
  // Compute rhs == x^3 + a x + b (mod p)
  BigInteger rhs = x.multiply(x).add(ec.getA()).multiply(x).add(ec.getB()).mod(p);
  BigInteger y = modSqrt(rhs, p);
  if (lsb != y.testBit(0)) {
    y = p.subtract(y).mod(p);
  }
  return new ECPoint(x, y);
}
 

import java.security.spec.EllipticCurve; //导入方法依赖的package包/类
/**
 * Decode a point on this curve which has been encoded using point
 * compression (X9.62 s 4.2.1 and 4.2.2) or regular encoding.
 * 
 * @param curve
 *            The elliptic curve.
 * @param encoded
 *            The encoded point.
 * @return the decoded point.
 */
public static ECPoint decodePoint(
   EllipticCurve curve, 
   byte[] encoded)
{
    ECCurve c = null;
    
    if (curve.getField() instanceof ECFieldFp)
    {
        c = new ECCurve.Fp(
                ((ECFieldFp)curve.getField()).getP(), curve.getA(), curve.getB());
    }
    else
    {
        int k[] = ((ECFieldF2m)curve.getField()).getMidTermsOfReductionPolynomial();
        
        if (k.length == 3)
        {
            c = new ECCurve.F2m(
                    ((ECFieldF2m)curve.getField()).getM(), k[2], k[1], k[0], curve.getA(), curve.getB());
        }
        else
        {
            c = new ECCurve.F2m(
                    ((ECFieldF2m)curve.getField()).getM(), k[0], curve.getA(), curve.getB());
        }
    }
    
    org.bouncycastle.math.ec.ECPoint p = c.decodePoint(encoded);

    return new ECPoint(p.getAffineXCoord().toBigInteger(), p.getAffineYCoord().toBigInteger());
}