Triple DES without using forward or backward slashes - asp.net-mvc

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

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 2

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 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));
}