Security.addProvider(new CryptoProvider());
        KeyPairGenerator kg = KeyPairGenerator.getInstance(JCP.GOST_DH_2012_256_NAME);//, CryptoProvider.PROVIDER_NAME);
        KeyPair keyPair = kg.generateKeyPair();

        Cipher cipher = Cipher.getInstance("GOST28147/CBC/PKCS5_PADDING");
        cipher.init(Cipher.ENCRYPT_MODE, keyPair.getPublic());
        byte[] ivArr = cipher.getIV();
        byte[] cryptedArr = cipher.update("abc123".getBytes(StandardCharsets.UTF_8));
        //
        IvParameterSpec spec = new IvParameterSpec(ivArr);
        cipher.init(Cipher.DECRYPT_MODE, keyPair.getPrivate(), spec);
        byte[] sourceArr = cipher.update(cryptedArr);