First attempt at getting a little meta data on the client. Included a value for peppering all password hashing functions.

SecureCore/Authentication/PasswordManager.cs

@@ -6,6 +6,10 @@ namespace SecureCore.Authentication
 {
     public class PasswordManager
     {
+        //Add some pepper to the passwords for good measure: 
+        //https://cheatsheetseries.owasp.org/cheatsheets/Password_Storage_Cheat_Sheet.html
+        public static string Pepper { get; } = "rVk/OwQUw01qy76Q+5WimPk+NdqUMMghftMXyJzzckOj/+eFn056PDYzBD61E/ZNjRdgiMK6RhcHEcdfpJdbcw==";
+
         private static string ConnectionString = @"Server=DESKTOP-OEDDVKC\SQLEXPRESS;Database=main;Integrated Security=true;";
 
         public PasswordManager()
@@ -18,14 +22,14 @@ namespace SecureCore.Authentication
 
             ByteGenerator.GetRandomBytes(ref salt);
 
-            return (GetPasswordHash(password, salt), Convert.ToBase64String(salt));
+            return (GetHash(password, salt), Convert.ToBase64String(salt));
         }
 
         public static bool PasswordIsValid(string password, string salt, string passwordHash)
         {
             var saltBytes = Convert.FromBase64String(salt);
 
-            return passwordHash == GetPasswordHash(password, saltBytes);
+            return passwordHash == GetHash(password, saltBytes);
         }
 
         public static (string PasswordHash, string SaltHash) GetUserPasswordHash(int userId)
@@ -49,9 +53,26 @@ namespace SecureCore.Authentication
             }
         }
 
-        private static string GetPasswordHash(string password, byte[] salt)
+        public static string HashStringData(string data, byte[] salt = null)
         {
-            return Convert.ToBase64String(KeyDerivation.Pbkdf2(password, salt, Settings.KeyType, Settings.Iterations, Settings.KeySize));
+            if (salt == null) salt = new byte[0];
+
+            return GetHash(data, salt);
+        }
+
+        public static string HashStringData(string data, string salt = "")
+        {
+            var saltBytes = new byte[0];
+
+            if(!string.IsNullOrEmpty(salt))
+                saltBytes = Convert.FromBase64String(salt);
+
+            return GetHash(data, saltBytes);
+        }
+
+        private static string GetHash(string password, byte[] salt)
+        {
+            return Convert.ToBase64String(KeyDerivation.Pbkdf2($"{password}{Pepper}", salt, Settings.KeyType, Settings.Iterations, Settings.KeySize));
         }
     }
 }