private ECPublicKey generateUserKey(String encodedKey) throws NoSuchAlgorithmException, NoSuchProviderException,
			InvalidAlgorithmParameterException, InvalidKeySpecException {

		// Get key parameters
		String xStr = encodedKey.substring(1, encodedKey.length() / 2 + 1);
		String yStr = encodedKey.substring(encodedKey.length() / 2 + 1, encodedKey.length());
		BigInteger x = new BigInteger(xStr, 16);
		BigInteger y = new BigInteger(yStr, 16);
		ECPoint w = new ECPoint(x, y);

		// Generate key sample to get curve parameters
		KeyPairGenerator g = KeyPairGenerator.getInstance("ECDSA", "BC");
		g.initialize(new ECGenParameterSpec("secp256k1"));
		ECParameterSpec params = ((ECPublicKey) g.generateKeyPair().getPublic()).getParams();

		// Generate key
		ECPublicKeySpec keySpec = new ECPublicKeySpec(w, params);
		ECPublicKey userKey = (ECPublicKey) KeyFactory.getInstance("ECDSA", "BC").generatePublic(keySpec);

		return userKey;
	}