private static ASN1ObjectIdentifier getCurveId(final String curveName) { ASN1ObjectIdentifier curveId = X962NamedCurves.getOID(curveName); if (curveId == null) { curveId = SECNamedCurves.getOID(curveName); } if (curveId == null) { curveId = TeleTrusTNamedCurves.getOID(curveName); } if (curveId == null) { curveId = NISTNamedCurves.getOID(curveName); } return curveId; }
public static byte[] privateKeyToPublicKey(String private_key, boolean compressed) { byte[] privateKeyBytes = null; try { privateKeyBytes = org.apache.commons.codec.binary.Hex.decodeHex(private_key.toCharArray()); } catch (DecoderException e1) { // TODO Auto-generated catch block e1.printStackTrace(); } X9ECParameters ecp = SECNamedCurves.getByName("secp256k1"); ECDomainParameters domainParams = new ECDomainParameters(ecp.getCurve(), ecp.getG(), ecp.getN(), ecp.getH(), ecp.getSeed()); ECPrivateKeyParameters privateKey = new ECPrivateKeyParameters(new BigInteger(1, privateKeyBytes), domainParams); System.out.println(privateKey.getD()); byte[] publicKeyBIBytes = privateKey.getD().toByteArray(); ECPoint Q = domainParams.getG().multiply(new BigInteger(publicKeyBIBytes)); byte[] publicKeyBytes = Q.getEncoded(compressed); return publicKeyBytes; }