Add authentication to shared

Author: weeryan17

.gitignore

@@ -14,3 +14,5 @@
 
 target/
 *.yml
+
+shared.iml

src/main/java/com/cascadebot/shared/Auth.java

@@ -0,0 +1,45 @@
+package com.cascadebot.shared;
+
+import javax.crypto.Mac;
+import javax.crypto.spec.SecretKeySpec;
+import java.nio.charset.StandardCharsets;
+import java.security.InvalidKeyException;
+import java.security.NoSuchAlgorithmException;
+
+public class Auth {
+
+    private Mac hmac;
+
+    public Auth(String key) throws NoSuchAlgorithmException, InvalidKeyException {
+        SecretKeySpec keySpec = new SecretKeySpec(key.getBytes(StandardCharsets.UTF_8), "HmacSHA512");
+        hmac = Mac.getInstance("HmacSHA512");
+        hmac.init(keySpec);
+    }
+
+    public String hmacEncrypt(String text) {
+        return toHex(hmac.doFinal(text.getBytes(StandardCharsets.UTF_8)));
+    }
+
+    public boolean verifyEncrypt(String text, String hmacText) {
+        return toHex(hmac.doFinal(text.getBytes(StandardCharsets.UTF_8))).equals(hmacText);
+    }
+
+    private static String digits = "0123456789abcdef";
+
+    public static String toHex(byte[] data) {
+        return toHex(data, data.length);
+    }
+
+    public static String toHex(byte[] data, int length) {
+        StringBuilder buf = new StringBuilder();
+
+        for(int i = 0; i != length; i++) {
+            int v = data[i] & 0xff;
+            buf.append(digits.charAt(v >> 4));
+            buf.append(digits.charAt(v & 0xf));
+        }
+
+        return buf.toString();
+
+    }
+}