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;
}
private byte[] bigIntToBytes(BigInteger r) {
return converter.integerToBytes(r, converter.getByteLength(parameters.getG().getX()));
}