How to decrypt using a MemoryStream rather than FileStream?

Question

Based on this Encryption/Decryption code sample:

///<summary>
/// Steve Lydford - 12/05/2008.
///
/// Encrypts a file using Rijndael algorithm.
///</summary>
///<param name="inputFile"></param>
///<param name="outputFile"></param>
private void EncryptFile(string inputFile, string outputFile)
{
    try
    {
        string password = @"myKey123"; // Your Key Here
        UnicodeEncoding UE = new UnicodeEncoding();
        byte[] key = UE.GetBytes(password);

        string cryptFile = outputFile;
        FileStream fsCrypt = new FileStream(cryptFile, FileMode.Create);

        RijndaelManaged RMCrypto = new RijndaelManaged();

        CryptoStream cs = new CryptoStream(fsCrypt,
            RMCrypto.CreateEncryptor(key, key),
            CryptoStreamMode.Write);

        FileStream fsIn = new FileStream(inputFile, FileMode.Open);

        int data;
        while ((data = fsIn.ReadByte()) != -1)
            cs.WriteByte((byte)data);

        fsIn.Close();
        cs.Close();
        fsCrypt.Close();
    }
    catch
    {
        MessageBox.Show("Encryption failed!", "Error");
    }
}

///<summary>
/// Steve Lydford - 12/05/2008.
///
/// Decrypts a file using Rijndael algorithm.
///</summary>
///<param name="inputFile"></param>
///<param name="outputFile"></param>
private void DecryptFile(string inputFile, string outputFile)
{
    {
        string password = @"myKey123"; // Your Key Here

        UnicodeEncoding UE = new UnicodeEncoding();
        byte[] key = UE.GetBytes(password);

        FileStream fsCrypt = new FileStream(inputFile, FileMode.Open);

        RijndaelManaged RMCrypto = new RijndaelManaged();

        CryptoStream cs = new CryptoStream(fsCrypt,
            RMCrypto.CreateDecryptor(key, key),
            CryptoStreamMode.Read);

        FileStream fsOut = new FileStream(outputFile, FileMode.Create);

        int data;
        while ((data = cs.ReadByte()) != -1)
            fsOut.WriteByte((byte)data);

        fsOut.Close();
        cs.Close();
        fsCrypt.Close();
    }
}

Using: System.Security, System.Security.Cryptography, System.Runtime.InteropServices, and System.Text.RegularExpressions namespaces.

I'm trying to use a Memory Stream instead of a file stream for the output (decryption).

Based on something I found here at Stack Overflow i tried my best:

namespace EncryptDecrypt
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
        }

        private void button1_Click(object sender, EventArgs e)
        {
            EncryptFile("Seriali_01.txt", "Seriali_01.007", @"mykey123");
            textBox1.Text = "Encrypted";
        }

        private void EncryptFile(string inputFile, string outputFile, string password)
        {
            try
            {
                //string password = @"mykey123"; // Your Key Here
                UnicodeEncoding UE = new UnicodeEncoding();
                byte[] key = UE.GetBytes(password);

                string cryptFile = outputFile;
                FileStream fsCrypt = new FileStream(cryptFile, FileMode.Create);

                RijndaelManaged RMCrypto = new RijndaelManaged();

                CryptoStream cs = new CryptoStream(fsCrypt,
                    RMCrypto.CreateEncryptor(key, key),
                    CryptoStreamMode.Write);

                FileStream fsIn = new FileStream(inputFile, FileMode.Open);

                int data;
                while ((data = fsIn.ReadByte()) != -1)
                    cs.WriteByte((byte)data);

                fsIn.Close();
                cs.Close();
                fsCrypt.Close();
            }
            catch
            {
                MessageBox.Show("Encryption failed!", "Error");
            }
        }

        private void DecryptFile(string inputFile, string password)
        {

            using (var ms = new MemoryStream())
            {
                //string password = @"myKey123"; // Your Key Here

                UnicodeEncoding UE = new UnicodeEncoding();
                byte[] key = UE.GetBytes(password);

                FileStream fsCrypt = new FileStream(inputFile, FileMode.Open);

                RijndaelManaged RMCrypto = new RijndaelManaged();

                CryptoStream cs = new CryptoStream(fsCrypt,
                    RMCrypto.CreateDecryptor(key, key),
                    CryptoStreamMode.Read);

                var fsOut = new StreamWriter(ms);
                //MemoryStream fsOut = new MemoryStream();

                int data;
                while ((data = cs.ReadByte()) != -1)
                    fsOut.Write((byte)data);

                fsOut.Flush();
                ms.Position = 0;
                var sr = new StreamReader(ms);
                var myStr = sr.ReadToEnd();
                textBox2.Text = myStr;

                fsOut.Close();
                cs.Close();
                fsCrypt.Close();
            }
        }

        private void button2_Click(object sender, EventArgs e)
        {
            DecryptFile("Seriali_01.007",  @"mykey123");
            textBox1.Text = "Encrypted";
        }
    }
}

The result is now working (I edited because i was pointing the decryptor to the wrong file) but i receive as output only a set of numbers.

This is the FileStrem example, it's working perfectly:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

using System.IO;
using System.Security;
using System.Security.Cryptography;
using System.Runtime.InteropServices;
using System.Text.RegularExpressions;

namespace Decrypt
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        ///<summary>
        /// Steve Lydford - 12/05/2008.
        ///
        /// Encrypts a file using Rijndael algorithm.
        ///</summary>
        ///<param name="inputFile"></param>
        ///<param name="outputFile"></param>
        private void EncryptFile(string inputFile, string outputFile)
        {

            try
            {
                string password = @"myKey123"; // Your Key Here
                UnicodeEncoding UE = new UnicodeEncoding();
                byte[] key = UE.GetBytes(password);

                string cryptFile = outputFile;
                FileStream fsCrypt = new FileStream(cryptFile, FileMode.Create);

                RijndaelManaged RMCrypto = new RijndaelManaged();

                CryptoStream cs = new CryptoStream(fsCrypt,
                    RMCrypto.CreateEncryptor(key, key),
                    CryptoStreamMode.Write);

                FileStream fsIn = new FileStream(inputFile, FileMode.Open);

                int data;
                while ((data = fsIn.ReadByte()) != -1)
                    cs.WriteByte((byte)data);


                fsIn.Close();
                cs.Close();
                fsCrypt.Close();
            }
            catch
            {
                MessageBox.Show("Encryption failed!", "Error");
            }
        }
        ///<summary>
        /// Steve Lydford - 12/05/2008.
        ///
        /// Decrypts a file using Rijndael algorithm.
        ///</summary>
        ///<param name="inputFile"></param>
        ///<param name="outputFile"></param>
        private void DecryptFile(string inputFile, string outputFile)
        {

            {
                string password = @"myKey123"; // Your Key Here

                UnicodeEncoding UE = new UnicodeEncoding();
                byte[] key = UE.GetBytes(password);

                FileStream fsCrypt = new FileStream(inputFile, FileMode.Open);

                RijndaelManaged RMCrypto = new RijndaelManaged();

                CryptoStream cs = new CryptoStream(fsCrypt,
                    RMCrypto.CreateDecryptor(key, key),
                    CryptoStreamMode.Read);

                FileStream fsOut = new FileStream(outputFile, FileMode.Create);

                int data;
                while ((data = cs.ReadByte()) != -1)
                    fsOut.WriteByte((byte)data);

                fsOut.Close();
                cs.Close();
                fsCrypt.Close();

            }
        }

        private void button1_Click(object sender, EventArgs e)
        {
            EncryptFile("hello.txt", "hello.007");
            textBox1.Text = "Encrypted";
        }

        private void button2_Click(object sender, EventArgs e)
        {
            DecryptFile("hello.007", "hello_dec.txt");
            textBox1.Text = "Decrypted";
        }


    }
}

Did you actually try if it works with a file stream or is that failing, too? — BitTickler, Apr 18 '15 at 23:09
Maybe because the filestream has the WriteByte function while the MemoryStream have not? — WizardingStudios, Apr 18 '15 at 23:24

How to decrypt using a MemoryStream rather than FileStream?

0 Answers0