added "UserPermissionTesting_CS_WinForms" project

UserPermissionTest_CS_WinForms/PasswordHasher.cs

@@ -0,0 +1,39 @@
+using System;
+using System.Security.Cryptography;
+using System.Text;
+
+namespace UserPermissionTest_CS_WinForms
+{
+    public static class PasswordHasher
+    {
+        /// <summary>
+        /// Hashes the plain-text password using SHA-256.
+        /// </summary>
+        public static string HashPassword(string password)
+        {
+            if (password == null) throw new ArgumentNullException(nameof(password));
+
+            using (SHA256 sha256 = SHA256.Create())
+            {
+                byte[] bytes = sha256.ComputeHash(Encoding.UTF8.GetBytes(password));
+                StringBuilder builder = new StringBuilder();
+                for (int i = 0; i < bytes.Length; i++)
+                {
+                    builder.Append(bytes[i].ToString("x2"));
+                }
+                return builder.ToString();
+            }
+        }
+
+        /// <summary>
+        /// Verifies whether the entered plain-text password matches the stored SHA-256 hash.
+        /// </summary>
+        public static bool VerifyPassword(string enteredPassword, string storedHash)
+        {
+            if (enteredPassword == null || storedHash == null) return false;
+
+            string hashedInput = HashPassword(enteredPassword);
+            return hashedInput.Equals(storedHash, StringComparison.OrdinalIgnoreCase);
+        }
+    }
+}