public static RSAPublicKey getKey(String filename)
            throws Exception {

            byte[] keyBytes = Files.readAllBytes(Paths.get(filename));

            X509EncodedKeySpec spec =
              new X509EncodedKeySpec(keyBytes);
            KeyFactory kf = KeyFactory.getInstance("RSA");
            return (RSAPublicKey)kf.generatePublic(spec);
    }

RSAPublicKey pubKey = (RSAPublicKey) GeneraKeysRsa.getKey(file);
CaviumRSAPublicKey key = (CaviumRSAPublicKey) pubKey;

ClassCastException: sun.security.rsa.RSAPublicKeyImpl cannot be cast to com.cavium.key.CaviumRSAPublicKey