Examples with X9ECParameters org.bouncycastle.asn1.x9.X9ECParameters used on opensource projects

Example 36 with X9ECParameters

use of org.bouncycastle.asn1.x9.X9ECParameters in project OsmAnd-tools by osmandapp.

the class SigningUtils method signData.

static String signData(String input, byte[] key) throws BlockIOException {
    ECDSASigner signer = new ECDSASigner(new HMacDSAKCalculator(new SHA256Digest()));
    X9ECParameters params = SECNamedCurves.getByName("secp256k1");
    ECDomainParameters ecParams = new ECDomainParameters(params.getCurve(), params.getG(), params.getN(), params.getH());
    BigInteger priv = new BigInteger(1, key);
    ECPrivateKeyParameters privKey = new ECPrivateKeyParameters(priv, ecParams);
    signer.init(true, privKey);
    BigInteger[] sigs = signer.generateSignature(fromHex(input));
    BigInteger r = sigs[0];
    BigInteger s = sigs[1];
    // BIP62: "S must be less than or equal to half of the Group Order N"
    BigInteger overTwo = params.getN().shiftRight(1);
    if (s.compareTo(overTwo) == 1) {
        s = params.getN().subtract(s);
    }
    try {
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        DERSequenceGenerator seq = new DERSequenceGenerator(bos);
        seq.addObject(new ASN1Integer(r));
        seq.addObject(new ASN1Integer(s));
        seq.close();
        return toHex(bos.toByteArray());
    } catch (IOException e) {
        // Cannot happen.
        throw new BlockIOException("That should never happen... File an issue report.");
    }
}