java.security.spec.ECParameterSpec#getCurve

Source File: ECOperations.java From dragonwell8_jdk with GNU General Public License v2.0

7 votes

public static Optional<ECOperations> forParameters(ECParameterSpec params) {

        EllipticCurve curve = params.getCurve();
        if (!(curve.getField() instanceof ECFieldFp)) {
            return Optional.empty();
        }
        ECFieldFp primeField = (ECFieldFp) curve.getField();

        BigInteger three = BigInteger.valueOf(3);
        if (!primeField.getP().subtract(curve.getA()).equals(three)) {
            return Optional.empty();
        }
        IntegerFieldModuloP field = fields.get(primeField.getP());
        if (field == null) {
            return Optional.empty();
        }

        IntegerFieldModuloP orderField = orderFields.get(params.getOrder());
        if (orderField == null) {
            return Optional.empty();
        }

        ImmutableIntegerModuloP b = field.getElement(curve.getB());
        ECOperations ecOps = new ECOperations(b, orderField);
        return Optional.of(ecOps);
    }

Source File: ECOperations.java From TencentKona-8 with GNU General Public License v2.0

6 votes

public static Optional<ECOperations> forParameters(ECParameterSpec params) {

        EllipticCurve curve = params.getCurve();
        if (!(curve.getField() instanceof ECFieldFp)) {
            return Optional.empty();
        }
        ECFieldFp primeField = (ECFieldFp) curve.getField();

        BigInteger three = BigInteger.valueOf(3);
        if (!primeField.getP().subtract(curve.getA()).equals(three)) {
            return Optional.empty();
        }
        IntegerFieldModuloP field = fields.get(primeField.getP());
        if (field == null) {
            return Optional.empty();
        }

        IntegerFieldModuloP orderField = orderFields.get(params.getOrder());
        if (orderField == null) {
            return Optional.empty();
        }

        ImmutableIntegerModuloP b = field.getElement(curve.getB());
        ECOperations ecOps = new ECOperations(b, orderField);
        return Optional.of(ecOps);
    }

Source File: ECOperations.java From openjdk-jdk8u with GNU General Public License v2.0

6 votes

public static Optional<ECOperations> forParameters(ECParameterSpec params) {

        EllipticCurve curve = params.getCurve();
        if (!(curve.getField() instanceof ECFieldFp)) {
            return Optional.empty();
        }
        ECFieldFp primeField = (ECFieldFp) curve.getField();

        BigInteger three = BigInteger.valueOf(3);
        if (!primeField.getP().subtract(curve.getA()).equals(three)) {
            return Optional.empty();
        }
        IntegerFieldModuloP field = fields.get(primeField.getP());
        if (field == null) {
            return Optional.empty();
        }

        IntegerFieldModuloP orderField = orderFields.get(params.getOrder());
        if (orderField == null) {
            return Optional.empty();
        }

        ImmutableIntegerModuloP b = field.getElement(curve.getB());
        ECOperations ecOps = new ECOperations(b, orderField);
        return Optional.of(ecOps);
    }

Source File: EcUtil.java From wycheproof with Apache License 2.0

6 votes

public static void printParameters(ECParameterSpec spec) {
  System.out.println("cofactor:" + spec.getCofactor());
  EllipticCurve curve = spec.getCurve();
  System.out.println("A:" + curve.getA());
  System.out.println("B:" + curve.getB());
  ECField field = curve.getField();
  System.out.println("field size:" + field.getFieldSize());
  if (field instanceof ECFieldFp) {
    ECFieldFp fp = (ECFieldFp) field;
    System.out.println("P:" + fp.getP());
  }
  ECPoint generator = spec.getGenerator();
  System.out.println("Gx:" + generator.getAffineX());
  System.out.println("Gy:" + generator.getAffineY());
  System.out.println("order:" + spec.getOrder());
}

Source File: EcUtil.java From wycheproof with Apache License 2.0

6 votes

/**
 * 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);
}

Source File: ECOperations.java From jdk8u_jdk with GNU General Public License v2.0

6 votes

public static Optional<ECOperations> forParameters(ECParameterSpec params) {

        EllipticCurve curve = params.getCurve();
        if (!(curve.getField() instanceof ECFieldFp)) {
            return Optional.empty();
        }
        ECFieldFp primeField = (ECFieldFp) curve.getField();

        BigInteger three = BigInteger.valueOf(3);
        if (!primeField.getP().subtract(curve.getA()).equals(three)) {
            return Optional.empty();
        }
        IntegerFieldModuloP field = fields.get(primeField.getP());
        if (field == null) {
            return Optional.empty();
        }

        IntegerFieldModuloP orderField = orderFields.get(params.getOrder());
        if (orderField == null) {
            return Optional.empty();
        }

        ImmutableIntegerModuloP b = field.getElement(curve.getB());
        ECOperations ecOps = new ECOperations(b, orderField);
        return Optional.of(ecOps);
    }

Source File: SM2NamedCurve.java From julongchain with Apache License 2.0

5 votes

private static SM2NamedCurve genSM2NamedCurve() {
    ECParameterSpec sm2ParameterSpec = Util.getECParameterSpec();
    return new SM2NamedCurve("sm2p256v1", "1.2.156.10197.1.301", sm2ParameterSpec.getCurve(),
            sm2ParameterSpec.getGenerator(),
            sm2ParameterSpec.getOrder(),
            sm2ParameterSpec.getCofactor());
}

Source File: JsonWebKey.java From azure-keyvault-java with MIT License

5 votes

private static JsonWebKeyCurveName getCurveFromKeyPair(KeyPair keyPair, Provider provider) {

        try {
            ECPublicKey key = (ECPublicKey) keyPair.getPublic();
            ECParameterSpec spec = key.getParams();
            EllipticCurve crv = spec.getCurve();

            List<JsonWebKeyCurveName> curveList = Arrays.asList(JsonWebKeyCurveName.P_256, JsonWebKeyCurveName.P_384,
                    JsonWebKeyCurveName.P_521, JsonWebKeyCurveName.P_256K);

            for (JsonWebKeyCurveName curve : curveList) {
                ECGenParameterSpec gps = new ECGenParameterSpec(CURVE_TO_SPEC_NAME.get(curve));
                KeyPairGenerator kpg = KeyPairGenerator.getInstance("EC", provider);
                kpg.initialize(gps);

                // Generate dummy keypair to get parameter spec.
                KeyPair apair = kpg.generateKeyPair();
                ECPublicKey apub = (ECPublicKey) apair.getPublic();
                ECParameterSpec aspec = apub.getParams();
                EllipticCurve acurve = aspec.getCurve();

                // Matches the parameter spec
                if (acurve.equals(crv)) {
                    return curve;
                }
            }

            // Did not find a supported curve.
            throw new NoSuchAlgorithmException("Curve not supported.");
        } catch (GeneralSecurityException e) {
            throw new IllegalStateException(e);
        }
    }

Source File: EcKey.java From azure-keyvault-java with MIT License

5 votes

private JsonWebKeyCurveName getCurveFromKeyPair(KeyPair keyPair) {
	try {
		ECPublicKey key = (ECPublicKey) keyPair.getPublic();
		ECParameterSpec spec = key.getParams();
		EllipticCurve crv = spec.getCurve();
		
		List<JsonWebKeyCurveName> curveList = Arrays.asList(JsonWebKeyCurveName.P_256, JsonWebKeyCurveName.P_384, JsonWebKeyCurveName.P_521, JsonWebKeyCurveName.P_256K);
		
		for (JsonWebKeyCurveName curve : curveList) {
			ECGenParameterSpec gps = new ECGenParameterSpec(CURVE_TO_SPEC_NAME.get(curve));
			KeyPairGenerator kpg = KeyPairGenerator.getInstance("EC", _provider);
			kpg.initialize(gps);
			
			// Generate dummy keypair to get parameter spec.
			KeyPair apair = kpg.generateKeyPair();
			ECPublicKey apub = (ECPublicKey) apair.getPublic();
			ECParameterSpec aspec = apub.getParams();
			EllipticCurve acurve = aspec.getCurve();
			
			//Matches the parameter spec
			if (acurve.equals(crv)) {
				return curve;
			}
		}
		
		//Did not find a supported curve.
		throw new IllegalArgumentException ("Curve not supported.");
	} catch (GeneralSecurityException e) {
		throw new IllegalStateException(e);
	}
}

Source File: EcUtil.java From wycheproof with Apache License 2.0

5 votes

/**
 * 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);
}

Source File: EcUtil.java From wycheproof with Apache License 2.0

5 votes

/**
 * 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);
  }
}

Source File: EllipticCurveJsonWebKey.java From Jose4j with Apache License 2.0

5 votes

public EllipticCurveJsonWebKey(ECPublicKey publicKey)
{
    super(publicKey);
    ECParameterSpec spec = publicKey.getParams();
    EllipticCurve curve = spec.getCurve();
    curveName = EllipticCurves.getName(curve);
}

Source File: EcdsaUsingShaAlgorithm.java From Jose4j with Apache License 2.0

5 votes

private void validateKeySpec(ECKey ecKey) throws InvalidKeyException
{
    ECParameterSpec spec = ecKey.getParams();
    EllipticCurve curve = spec.getCurve();

    String name = EllipticCurves.getName(curve);

    if (!getCurveName().equals(name))
    {
        throw new InvalidKeyException(getAlgorithmIdentifier() + "/" + getJavaAlgorithm() + " expects a key using " +
                getCurveName() + " but was " + name);
    }
}

Java Code Examples for java.security.spec.ECParameterSpec#getCurve()