Triple DES without using forward or backward slashes

Question

Is it possible to modify triple DES so as not to include forward and backward slashes when encrypting/decrypting?

I had this actionlink on mvc which works without encryption however when I tried to encrypt the id passed to the controller method, the id was being encrypted and included some forward slashes (/vO5Ppr4+Phzx+lHD4Jp6JubZlYXK0Az9OA9J8urf+MJFw62c3Y0Q/Q==) thus I am getting a 404 not found and the controller method is not being called.

MVC ActionLink:

<span> | </span> @Html.ActionLink("Student Rights", "StudentRights","Threads", new { id = CommonLayer.Securities.Encryption.EncryptTripleDES(item.ID) }, null)

Encryption Method:

private static byte[] KEY_192 = 
        {
            111,21,12,65,21,12,2,1,
            5,30,34,78,98,1,32,122,
            123,124,125,126,212,212,213,214
        };

    private static byte[] IV_192 = 
        {
            1,2,3,4,5,12,13,14,
            13,14,15,13,17,21,22,23,
            24,25,121,122,122,123,124,124
        };

    /// <summary>
    /// Encrypt using TripleDES
    /// </summary>
    /// <param name="vl">String to Encrypt</param>
    /// <returns>Encrypted String</returns>
    public static String EncryptTripleDES(String vl)
    {
        if (vl != "")
        { 
            TripleDESCryptoServiceProvider cryptoprovider = new TripleDESCryptoServiceProvider();
            MemoryStream ms = new MemoryStream();
            CryptoStream cs = new CryptoStream(ms, cryptoprovider.CreateEncryptor(KEY_192, IV_192), CryptoStreamMode.Write);
            StreamWriter sw = new StreamWriter(cs);
            sw.Write(vl);
            sw.Flush();
            cs.FlushFinalBlock();
            ms.Flush();
            return Convert.ToBase64String(ms.GetBuffer(), 0, (int)ms.Length);
        } 
        return "";
    } 

    /// <summary>
    /// Decrypt using TripleDES
    /// </summary>
    /// <param name="vl">String to Decrypt</param>
    /// <returns>Decrypted String</returns>
    public static String DecryptTripleDES(String vl)
    { 
        if (vl != "")
        { 
            TripleDESCryptoServiceProvider cryptoprovider = new TripleDESCryptoServiceProvider();
            Byte[] buffer = Convert.FromBase64String(vl);
            MemoryStream ms = new MemoryStream(buffer);
            CryptoStream cs = new CryptoStream(ms, cryptoprovider.CreateDecryptor(KEY_192, IV_192), CryptoStreamMode.Read);
            StreamReader sw = new StreamReader(cs);
            return sw.ReadToEnd();
        } 
        return "";
    }

Answer 1

That's not the output of 3DES, that's Base 64 encoding of random (looking) binary data.

You can simply (raw) URL-encode the result or you can replace the character by any other. Check the Base 64 page on Wikipedia for ideas. Try and keep to common standards, such a replacing the + with -, and replacing / with _ as standardized by RFC 4648.

You may also want to remove the = characters at the end. This works if your base 64 library can decode such base 64, otherwise you can simply append them again until you got a string that has a multiple of 4 base 64 characters.

Answer 2

Like owlstead suggests, use the url safe Base64 encoding described in RFC 4648.

My implementation produces a bit much garbage, but for short strings it shouldn't matter much as long as you don't call this a million times a second.

public static string ToUrlSafeBase64(byte[] bytes)
{
    return Convert.ToBase64String(bytes).Replace('+', '-').Replace('/', '_').Replace("=","");
}

public static byte[] FromUrlSafeBase64(string s)
{
    while (s.Length % 4 != 0)
        s += "=";
    s = s.Replace('-', '+').Replace('_', '/');
    return Convert.FromBase64String(s);
}

Used as:

var str = ToUrlSafeBase64(bytes);

var bytes = FromUrlSafeBase64(str);

Answer 3

the following functions worked on another post why-is-base64-encode-adding-a-slash-in-the-result

function mybase64_encode($s) {
    return str_replace(array('+', '/'), array(',', '-'), base64_encode($s));
}


function mybase64_decode($s) {
    return base64_decode(str_replace(array(',', '-'), array('+', '/'), $s));
}