Examples with Signature com.github.rosklyar.crypto.Signature used on opensource projects

Example 1 with Signature

use of com.github.rosklyar.crypto.Signature in project nem-library by rosklyar.

the class Ed25519DsaSigner method sign.

@Override
public Signature sign(final byte[] data) {
    if (!this.getKeyPair().hasPrivateKey()) {
        throw new CryptoException("cannot sign without private key");
    }
    // Hash the private key to improve randomness.
    final byte[] hash = Hashes.sha3_512(ArrayUtils.toByteArray(this.getKeyPair().getPrivateKey().getRaw(), 32));
    // r = H(hash_b,...,hash_2b-1, data) where b=256.
    final Ed25519EncodedFieldElement r = new Ed25519EncodedFieldElement(Hashes.sha3_512(// only include the last 32 bytes of the private key hash
    Arrays.copyOfRange(hash, 32, 64), data));
    // Reduce size of r since we are calculating mod group order anyway
    final Ed25519EncodedFieldElement rModQ = r.modQ();
    // R = rModQ * base point.
    final Ed25519GroupElement R = Ed25519Group.BASE_POINT.scalarMultiply(rModQ);
    final Ed25519EncodedGroupElement encodedR = R.encode();
    // S = (r + H(encodedR, encodedA, data) * a) mod group order where
    // encodedR and encodedA are the little endian encodings of the group element R and the public key A and
    // a is the lower 32 bytes of hash after clamping.
    final Ed25519EncodedFieldElement h = new Ed25519EncodedFieldElement(Hashes.sha3_512(encodedR.getRaw(), this.getKeyPair().getPublicKey().getRaw(), data));
    final Ed25519EncodedFieldElement hModQ = h.modQ();
    final Ed25519EncodedFieldElement encodedS = hModQ.multiplyAndAddModQ(Ed25519Utils.prepareForScalarMultiply(this.getKeyPair().getPrivateKey()), rModQ);
    // Signature is (encodedR, encodedS)
    final Signature signature = new Signature(encodedR.getRaw(), encodedS.getRaw());
    if (!this.isCanonicalSignature(signature)) {
        throw new CryptoException("Generated signature is not canonical");
    }
    return signature;
}