MailGun Webhook Signature Validation

MailGun.java

private static final key = "mailgun_key"
public static boolean isSignatureValid(String token , long timestamp, String signature) {
		try {
			Mac hmac = Mac.getInstance("HmacSHA256");
			SecretKeySpec signingKey = new SecretKeySpec(key.getBytes(), "HmacSHA256");
			hmac.init(signingKey);
			String signed = Hex.encodeHexString(hmac.doFinal((timestamp + token).getBytes()));
			if (signed.equals(signature)) {
				return true;
			}
			return false;
		} catch (NoSuchAlgorithmException | InvalidKeyException e) {
			return false;
		}
	}