#33 [feat] : 해시 유틸 추가

backend/src/main/java/org/dgu/backend/util/HashUtil.java

@@ -0,0 +1,30 @@
+package org.dgu.backend.util;
+
+import java.io.UnsupportedEncodingException;
+import java.math.BigInteger;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.util.List;
+import java.util.Map;
+import java.util.ArrayList;
+
+public class HashUtil {
+    public static String buildQueryString(Map<String, String> params) {
+        List<String> queryElements = new ArrayList<>();
+        for (Map.Entry<String, String> entry : params.entrySet()) {
+            queryElements.add(entry.getKey() + "=" + entry.getValue());
+        }
+        return String.join("&", queryElements);
+    }
+
+    public static String generateQueryHash(String queryString) {
+        try {
+            MessageDigest md = MessageDigest.getInstance("SHA-512");
+            md.update(queryString.getBytes("UTF-8"));
+            byte[] hashBytes = md.digest();
+            return String.format("%0128x", new BigInteger(1, hashBytes));
+        } catch (NoSuchAlgorithmException | UnsupportedEncodingException e) {
+            throw new RuntimeException("SHA-512 해시 생성 실패: " + e.getMessage(), e);
+        }
+    }
+}