Encrypt And Decrypt Value In ASP.NET Using C#

Here I am storing the values in database using LINQ queries as encrypted form.

We can encrypt or decrypt values using other algorithms.

But here, I am using SALT to encrypt and decrypt the values.

Step 1:

public byte[] AES_Encrypt(byte[] bytesToBeEncrypted, byte[] passwordBytes)
{
    byte[] encryptedBytes = null;

    // Set your salt here, change it to meet your flavor:
    byte[] saltBytes = passwordBytes;
    // Example:
    //saltBytes = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };

    using (MemoryStream ms = new MemoryStream())
    {
        using (RijndaelManaged AES = new RijndaelManaged())
        {
            AES.KeySize = 256;
            AES.BlockSize = 128;

            var key = new Rfc2898DeriveBytes(passwordBytes, saltBytes, 1000);
            AES.Key = key.GetBytes(AES.KeySize / 8);
            AES.IV = key.GetBytes(AES.BlockSize / 8);

            AES.Mode = CipherMode.CBC;

            using (CryptoStream cs = new CryptoStream(ms, AES.CreateEncryptor(), CryptoStreamMode.Write))
            {
                cs.Write(bytesToBeEncrypted, 0, bytesToBeEncrypted.Length);
                cs.Close();
            }
            encryptedBytes = ms.ToArray();
        }
    }

    return encryptedBytes;
}
public byte[] AES_Decrypt(byte[] bytesToBeDecrypted, byte[] passwordBytes)
{
    try
    {
        byte[] decryptedBytes = null;
        // Set your salt here to meet your flavor:
        byte[] saltBytes = passwordBytes;
        // Example:
        //saltBytes = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };

        using (MemoryStream ms = new MemoryStream())
        {
            using (RijndaelManaged AES = new RijndaelManaged())
            {
                AES.KeySize = 256;
                AES.BlockSize = 128;

                var key = new Rfc2898DeriveBytes(passwordBytes, saltBytes, 1000);
                AES.Key = key.GetBytes(AES.KeySize / 8);
                AES.IV = key.GetBytes(AES.BlockSize / 8);

                //AES.Mode = CipherMode.CBC;

                using (CryptoStream cs = new CryptoStream(ms, AES.CreateDecryptor(), CryptoStreamMode.Write))
                {
                    cs.Write(bytesToBeDecrypted, 0, bytesToBeDecrypted.Length);
                    //If(cs.Length = ""
                    cs.Close();
                }
                decryptedBytes = ms.ToArray();
            }
        }
        return decryptedBytes;
    }
    catch (Exception Ex)
    {
        return null;
    }
}
public string Encrypt(string text, string pwd)
{
    byte[] originalBytes = Encoding.UTF8.GetBytes(text);
    byte[] encryptedBytes = null;
    byte[] passwordBytes = Encoding.UTF8.GetBytes(pwd);

    // Hash the password with SHA256
    passwordBytes = SHA256.Create().ComputeHash(passwordBytes);

    // Getting the salt size
    int saltSize = GetSaltSize(passwordBytes);
    // Generating salt bytes
    byte[] saltBytes = GetRandomBytes(saltSize);

    // Appending salt bytes to original bytes
    byte[] bytesToBeEncrypted = new byte[saltBytes.Length + originalBytes.Length];
    for (int i = 0; i < saltBytes.Length; i++)
    {
        bytesToBeEncrypted[i] = saltBytes[i];
    }
    for (int i = 0; i < originalBytes.Length; i++)
    {
        bytesToBeEncrypted[i + saltBytes.Length] = originalBytes[i];
    }

    encryptedBytes = AES_Encrypt(bytesToBeEncrypted, passwordBytes);

    return Convert.ToBase64String(encryptedBytes);
}
public string Decrypt(string decryptedText, string pwd)
{
    byte[] bytesToBeDecrypted = Convert.FromBase64String(decryptedText);
    byte[] passwordBytes = Encoding.UTF8.GetBytes(pwd);

    // Hash the password with SHA256
    passwordBytes = SHA256.Create().ComputeHash(passwordBytes);

    byte[] decryptedBytes = AES_Decrypt(bytesToBeDecrypted, passwordBytes);

    if (decryptedBytes != null)
    {
        // Getting the size of salt
        int saltSize = GetSaltSize(passwordBytes);

        // Removing salt bytes, retrieving original bytes
        byte[] originalBytes = new byte[decryptedBytes.Length - saltSize];
        for (int i = saltSize; i < decryptedBytes.Length; i++)
        {
            originalBytes[i - saltSize] = decryptedBytes[i];
        }
        return Encoding.UTF8.GetString(originalBytes);
    }
    else
    {
        return null;
    }
}
private int GetSaltSize(byte[] passwordBytes)
{
    var key = new Rfc2898DeriveBytes(passwordBytes, passwordBytes, 1000);
    byte[] ba = key.GetBytes(2);
    StringBuilder sb = new StringBuilder();
    for (int i = 0; i < ba.Length; i++)
    {
        sb.Append(Convert.ToInt32(ba[i]).ToString());
    }
    int saltSize = 0;
    string s = sb.ToString();
    foreach (char c in s)
    {
        int intc = Convert.ToInt32(c.ToString());
        saltSize = saltSize + intc;
    }

    return saltSize;
}
public byte[] GetRandomBytes(int length)
{
    byte[] ba = new byte[length];
    RNGCryptoServiceProvider.Create().GetBytes(ba);
    return ba;
}

public bool Add(Movy movie)
{
    demo.Movies.InsertOnSubmit(movie);
    demo.SubmitChanges();
    return true;
}

Step 2: Call that methods in .cs file.

public partial class Add: System.Web.UI.Page
{
    /// <summary>
    /// Linq To SQL : Connection object.
    /// </summary>
    DemoDataContext demo = new DemoDataContext();

    protected void Page_Load(object sender, EventArgs e)
    {

    }

    /// <summary>
    /// Button submit click event : Storing value in database as encrypted form
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    protected void btnSubmit_Click(object sender, EventArgs e) {
        try {
            if (txtName.Text != "")
            {
                var m = new Movy
                {
                    MovieName = new SecurityClass().Encrypt(txtName.Text, txtName.Text),
                };
                new SecurityClass().Add(m);
                lblMessgae.Text = "Submitted successfully.";
                txtName.Text = "";
            }
        }
        catch (Exception ex)
        {
            ex.Message.ToString();
        }
    }

    protected void btnSearch_Click(object sender, EventArgs e) {
        try {
            if (txtSearchByName.Text != "")
            {
                var movienameEncrypted = new SecurityClass().Encrypt(txtName.Text, txtName.Text);
                if (movienameEncrypted != null)
                {
                    string movienameDecrypt = new SecurityClass().Decrypt(movienameEncrypted, txtSearchByName.Text);
                    if (movienameDecrypt != null)
                    {
                        var Details = (from m in demo.Movies where movienameDecrypt == txtSearchByName.Text select new
                        {
                            UserName = m.Id
                        })
                        .FirstOrDefault();
                        if (Details != null)
                        {
                            lblMessgae.Text = "Movie exist into the database.";
                        }
                        else
                        {
                            lblMessgae.Text = "Not exist.";
                        }
                    }
                    else
                    {
                        lblMessgae.Text = "Not exist.";
                    }
                }
            }
        }
        catch (Exception ex)
        {
            ex.Message.ToString();
        }
    }

Screen: