Examples with EllipticCurve java.security.spec.EllipticCurve used on opensource projects

Example 21 with EllipticCurve

use of java.security.spec.EllipticCurve in project wycheproof by google.

the class EcUtil method getPoint.

/**
 * 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);
}

Example 22 with EllipticCurve

use of java.security.spec.EllipticCurve in project wycheproof by google.

the class EcUtil method printParameters.

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());
}

Example 23 with EllipticCurve

use of java.security.spec.EllipticCurve in project wycheproof by google.

the class EcUtil method getWeakPublicKey.

/**
 * 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);
    }
}

Example 24 with EllipticCurve

use of java.security.spec.EllipticCurve in project spring-security by spring-projects.

the class TestKeys method generateEcKeyPair.

static KeyPair generateEcKeyPair() {
    EllipticCurve ellipticCurve = new EllipticCurve(new ECFieldFp(new BigInteger("115792089210356248762697446949407573530086143415290314195533631308867097853951")), new BigInteger("115792089210356248762697446949407573530086143415290314195533631308867097853948"), new BigInteger("41058363725152142129326129780047268409114441015993725554835256314039467401291"));
    ECPoint ecPoint = new ECPoint(new BigInteger("48439561293906451759052585252797914202762949526041747995844080717082404635286"), new BigInteger("36134250956749795798585127919587881956611106672985015071877198253568414405109"));
    ECParameterSpec ecParameterSpec = new ECParameterSpec(ellipticCurve, ecPoint, new BigInteger("115792089210356248762697446949407573529996955224135760342422259061068512044369"), 1);
    KeyPair keyPair;
    try {
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("EC");
        keyPairGenerator.initialize(ecParameterSpec);
        keyPair = keyPairGenerator.generateKeyPair();
    } catch (Exception ex) {
        throw new IllegalStateException(ex);
    }
    return keyPair;
}

Example 25 with EllipticCurve

use of java.security.spec.EllipticCurve in project dhis2-core by dhis2.

the class KeyGeneratorUtils method generateEcKey.

static KeyPair generateEcKey() {
    EllipticCurve ellipticCurve = new EllipticCurve(new ECFieldFp(new BigInteger("115792089210356248762697446949407573530086143415290314195533631308867097853951")), new BigInteger("115792089210356248762697446949407573530086143415290314195533631308867097853948"), new BigInteger("41058363725152142129326129780047268409114441015993725554835256314039467401291"));
    ECPoint ecPoint = new ECPoint(new BigInteger("48439561293906451759052585252797914202762949526041747995844080717082404635286"), new BigInteger("36134250956749795798585127919587881956611106672985015071877198253568414405109"));
    ECParameterSpec ecParameterSpec = new ECParameterSpec(ellipticCurve, ecPoint, new BigInteger("115792089210356248762697446949407573529996955224135760342422259061068512044369"), 1);
    KeyPair keyPair;
    try {
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("EC");
        keyPairGenerator.initialize(ecParameterSpec);
        keyPair = keyPairGenerator.generateKeyPair();
    } catch (Exception ex) {
        throw new IllegalStateException(ex);
    }
    return keyPair;
}