今更ですが、TripleDES。
Macでdotnet coreで作成。

dotnet new console -o testdes
cd testdes
dotnet restore

using System;
using System.Text;
using System.Security.Cryptography;
using System.IO;

namespace test
{
    class Program
    {
        static void Main(string[] args)
        {
            //準備 =================================================================================

            //key, iv
            byte[] key = Encoding.UTF8.GetBytes("123456789012345678901234"); //半角24文字 196bit
            byte[] iv = Encoding.UTF8.GetBytes("12345678"); //半角8文字 64bit

            //3DES
            TripleDESCryptoServiceProvider des = new TripleDESCryptoServiceProvider();

            //文字列
            string srcStr = "hogehoge";
            //出力
            Console.WriteLine("元の文字列: " + srcStr);

            //暗号化処理 ============================================================================

            //byte変換
            byte[] srcByte = Encoding.UTF8.GetBytes(srcStr);

            //MemoryStream
            MemoryStream ms = new MemoryStream();
            //CryptoStream
            CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(key, iv), CryptoStreamMode.Write);

            cs.Write(srcByte, 0, srcByte.Length);
            cs.Close();

            byte[] encData = ms.ToArray();
            ms.Close();
            　
            　//普通に出力すると文字化け？するので、Base64でエンコード。
            string encStr = System.Convert.ToBase64String(encData);
            Console.WriteLine("暗号化+Base64: " + encStr);

            //複合処理 ============================================================================
            byte[] encByte = System.Convert.FromBase64String(encStr);

            MemoryStream ms2 = new MemoryStream();
            CryptoStream cs2 = new CryptoStream(ms2, des.CreateDecryptor(key, iv), CryptoStreamMode.Write);

            cs2.Write(encByte, 0, encByte.Length);
            cs2.Close();

            byte[] decByte = ms2.ToArray();
            ms2.Close();

            string decStr = Encoding.UTF8.GetString(decByte);
            Console.WriteLine("複合: " + decStr);
        }
    }
}

dotnet run

元の文字列: hogehoge
暗号化+Base64: cadNJMDQ934XJDU8Tx7b/g==
複合: hogehoge