Question

I tried to encrypt a string with System.Security.Cryptography.DES but I found that every time I run The program the result of encryption changed !
I don’t know how to get the same result each time I run the application ? IS there constant key or anything else to add to get the same result ?
I want when I enter “google” in this code

byte[] plaintextBytes = (new UnicodeEncoding()).GetBytes(expireddate);
            SymmetricAlgorithm sa = DES.Create();
            MemoryStream msEncrypt = new MemoryStream();
            CryptoStream csEncrypt = new CryptoStream(msEncrypt, sa.CreateEncryptor(), CryptoStreamMode.Write);
            csEncrypt.Write(plaintextBytes, 0, plaintextBytes.Length);
            csEncrypt.Close();
            byte[] encryptedTextBytes = msEncrypt.ToArray();

get “google” from this code when I entered the result of array of bytes in next time i opened the application ?

MemoryStream msDecrypt = new MemoryStream(decodedlistbyte.ToArray());
            CryptoStream csDecrypt = new CryptoStream(msDecrypt, sa.CreateDecryptor(), CryptoStreamMode.Read);
            byte[] decryptedTextBytes = new Byte[decodedlistbyte.Count];
            csDecrypt.Read(decryptedTextBytes, 0, decodedlistbyte.Count);
            csDecrypt.Close();
            msDecrypt.Close();
            string decrypteddate = (new UnicodeEncoding()).GetString(decryptedTextBytes);

Answer 1

I recommend you use a strong symmetric key algorithm such as AES (i.e. Rijndael). Have a look at the RijndaelManaged class in .NET. The same key can be used for encryption and decryption, which is why it’s a symmetric algorithm. The security of the key is vital, so keep it private and store it securely.