@Override
    protected boolean engineVerify(byte[] sigBytes) throws SignatureException {
        if (key == null) {
            // This can't actually happen, but you never know...
            throw new SignatureException("No key provided");
        }

        try {
            int result = NativeCrypto.ECDSA_verify(
                    buffer.array(), buffer.size(), sigBytes, key.getNativeRef());
            if (result == -1) {
                throw new SignatureException("Could not verify signature.");
            }
            return result == 1;
        } catch (Exception ex) {
            throw new SignatureException(ex);
        } finally {
            buffer.reset();
        }
    }
Buffer to hold value to be signed or verified.
common/src/main/java/org/conscrypt/OpenSSLSignatureRawECDSA.java