The variables are strOrig (PlainText) and strKey (Passphrase)

System.IO.MemoryStream ms = new System.IO.MemoryStream();
            System.Security.Cryptography.RijndaelManaged rj = new System.Security.Cryptography.RijndaelManaged();
            rj.Mode = System.Security.Cryptography.CipherMode.CBC;

            RandomNumberGenerator rng = RandomNumberGenerator.Create();
            byte[] salt = new byte[8];
            rng.GetBytes(salt);

            PasswordDeriveBytes pdb = new PasswordDeriveBytes(strKey, salt);
            rj.IV = pdb.GetBytes(16);
            rj.Key = pdb.GetBytes(32);

// Debug so I can see the IV, Key, and Salt Generated
            string strIV = Encoding.UTF8.GetString(rj.IV);
            string _strKey = Encoding.UTF8.GetString(rj.Key);
            string strSalt = Encoding.UTF8.GetString(salt);

            ms.Write(Encoding.UTF8.GetBytes("Salted__"), 0, Encoding.UTF8.GetByteCount("Salted__"));
            ms.Write(salt, 0, salt.Length);
            ms.Write(rj.IV, 0, rj.IV.Length);

            byte[] bOrig = Encoding.UTF8.GetBytes(strOrig);

            System.Security.Cryptography.CryptoStream cs = new System.Security.Cryptography.CryptoStream(ms, rj.CreateEncryptor(), System.Security.Cryptography.CryptoStreamMode.Write);

            cs.Write(bOrig, 0, bOrig.Length);
            cs.FlushFinalBlock();

            string bResult = Convert.ToBase64String(ms.ToArray());
            bResult = bResult.Remove(0, 10);
            ms.Flush();

            return bResult;