Random encryption of string in C#

Question

I wanted to encrypt a string value with this method.

    public string EncryptString(string inputString)
    {

       MemoryStream memStream = null;

        try
        {
            byte[] key = { };
            byte[] IV = { 12, 21, 43, 17, 57, 35, 67, 27 };
            string encryptKey = "aXb2uy4z";
            key = Encoding.UTF8.GetBytes(encryptKey);
            byte[] byteInput = Encoding.UTF8.GetBytes(inputString);
            DESCryptoServiceProvider provider = new DESCryptoServiceProvider();
            memStream = new MemoryStream();
            ICryptoTransform transform = provider.CreateEncryptor(key, IV);
            CryptoStream cryptoStream = new CryptoStream(memStream, transform, CryptoStreamMode.Write);
            cryptoStream.Write(byteInput, 0, byteInput.Length);
            cryptoStream.FlushFinalBlock();

        }
        catch (Exception ex)
        {
            Response.Write(ex.Message);
        }
        return Convert.ToBase64String(memStream.ToArray());
    }

The thing I want to do is that the encrypted string will always be random. Any one know how to do it? Please help.

What do you mean by random? If you encrypt the same string twice in a row, would you get two different answers? Then what good is that? — Erik, Jan 30 '15 at 07:15
use rijndael encryption with a Salt. it will make sure your encrypted string is always different. — Banana, Jan 30 '15 at 07:16
You may append *random noise* to the string before encryption: `"abc"` -> `abc\01g6$...`. When decrypted just cut off the noise — Dmitry Bychenko, Jan 30 '15 at 07:18
or you can add some random cipher key to your characters randomly, but you have to keep your cipher key with your encrypted string in a sequential manner so that you can decrypt them again. — Rohit Prakash, Jan 30 '15 at 07:25

score 0 · Answer 1 · answered Jan 30 '15 at 07:19

0

Here is the code:

StringBuilder sb = new StringBuilder();
Random r = new Random();
for (int i = 0; i < r.Next(100); i++) sb.Append((char)r.Next(65, 255));
string s = sb.ToString();

Make sure you store the string or you won't be able to decrypt

answered Jan 30 '15 at 07:19

Jonathan Camilleri

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score 0 · Answer 2 · edited May 23 '17 at 10:26

If you want some random value for your encryption (for example a salt value, to make the usage of rainbow tables impossible), i always use Guids. They are unique and "random".

Be sure to keep your salt, because you will need it later, for example, if you want to proof wether a password is correct:

PASSWORD + SALT --encryption--> Hash

If you forget the salt, you will not be able to build the same Hash again.

If you want to encrypt passwords, you algorithm is not very useful. I would take the following code-snippet from SO: sha-256 hash in C#

Just be sure, that you pass password + hash to the method, to get your encrypted value with some random "touch".

Random encryption of string in C#

2 Answers2