Example usage for org.bouncycastle.asn1.x9 X962Parameters getParameters

Introduction

In this page you can find the example usage for org.bouncycastle.asn1.x9 X962Parameters getParameters.

Prototype

public ASN1Primitive getParameters() 

Source Link

Usage

From source file:eu.betaas.taas.securitymanager.common.ec.ECKeyPairGen.java

License:Apache License

/**
 * A method to reconstruct an ECPublicKey from a SubjectPublicKeyInfo of a 
 * certificate /*from   ww  w.j  a  va 2  s  .  co  m*/
 * @param info: SubjectPublicKeyInfo in a X509Certificate
 * @return: ECPublicKeyParameters
 */
public static ECPublicKeyParameters generateECPublicKey(SubjectPublicKeyInfo info) {
    X962Parameters as = (X962Parameters) info.getAlgorithm().getParameters();
    DERSequence aa = (DERSequence) as.getParameters();
    Enumeration en = aa.getObjects();
    ECCurve curve = null;
    org.bouncycastle.math.ec.ECPoint g = null;
    byte[] seed = null;
    BigInteger h = null;
    BigInteger n = null;
    while (en.hasMoreElements()) {
        Object oen = en.nextElement();
        if (oen instanceof X9Curve) {
            curve = ((X9Curve) oen).getCurve();
            seed = ((X9Curve) oen).getSeed();
        } else if (oen instanceof X9ECPoint) {
            g = ((X9ECPoint) oen).getPoint();
        } else if (oen instanceof ASN1Integer) {
            BigInteger xoen = ((ASN1Integer) oen).getValue();
            if (xoen.equals(BigInteger.ONE))
                h = xoen;
            else
                n = xoen;
        }
    }

    ASN1OctetString key = new DEROctetString(info.getPublicKeyData().getBytes());
    X9ECPoint derQ = new X9ECPoint(curve, key);

    ECDomainParameters dParams = new ECDomainParameters(curve, g, n, h, seed);

    return new ECPublicKeyParameters(derQ.getPoint(), dParams);
}

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