Encryption/decryption gives Invalid character in a Base-64 string

Question

Hi,

I have been working with encryption/decryption RijndaelManaged alogorithm.

While encrypting a GUID we get "%" symbol in the middle of the encrypted algorithm. When I decrypt the same encrypted GUI i get a " Invalid character in a Base-64 string" error. This occurs due to the presence of % symbol in the encrypted token.

Here is the Code for encryption and decryption,

using System;
using System.Configuration;
using System.IO;
using System.Security.Cryptography;

public class ABC_RMCryptography
{
    public string Decrypt(string strValueIn)
    {
        try
        {
            byte[] arrB = System.Convert.FromBase64String(strValueIn);
            string strRC;

            byte[] key = System.Convert.FromBase64String(ConfigurationManager.AppSettings["TokenEncryptionKey"]);
            byte[] IV = System.Convert.FromBase64String(ConfigurationManager.AppSettings["TokenEncryptionVector"]);

            MemoryStream memStream = new MemoryStream(arrB);
            RijndaelManaged RMCrypto = new RijndaelManaged();
            CryptoStream CryptStream = new CryptoStream(memStream, RMCrypto.CreateDecryptor(key, IV), CryptoStreamMode.Read);

            StreamReader SReader = new StreamReader(CryptStream);
            strRC = SReader.ReadToEnd();
            SReader.Close();

            return strRC;
        }
        catch (Exception ex)
        {
            throw ex;
        }
    }

    public string Encrypt(string strValue)
    {
        MemoryStream memStream = new MemoryStream();

        try
        {
            byte[] key = System.Convert.FromBase64String(ConfigurationManager.AppSettings["TokenEncryptionKey"]);
            byte[] IV = System.Convert.FromBase64String(ConfigurationManager.AppSettings["TokenEncryptionVector"]);

            RijndaelManaged RMCrypto = new RijndaelManaged();

            CryptoStream CryptStream = new CryptoStream(memStream, RMCrypto.CreateEncryptor(key, IV), CryptoStreamMode.Write);
            StreamWriter SWriter = new StreamWriter(CryptStream);

            SWriter.Write(strValue);
            SWriter.Close();
            CryptStream.Close();

            byte[] b = memStream.ToArray();
            return Convert.ToBase64String(b);
        }
        catch (Exception ex)
        {
            throw ex;
        }

    }

    private string GenerateRMKey()
    {

        RijndaelManaged objRM = new RijndaelManaged();
        objRM.GenerateKey();
        return Convert.ToBase64String(objRM.Key);

    }

    private string GenerateRMIV()
    {

        RijndaelManaged objRM = new RijndaelManaged();
        objRM.GenerateKey();
        return Convert.ToBase64String(objRM.IV);

    }

}

Please let me know the solution to avoid this exception. How do I avoid % symbol?

Encryption/decryption gives Invalid character in a Base-64 string

Answer 1

Where exactly is the % coming from? It shouldn't be part of the return value from the Encrypt method.

My guess is that you've got something performing URL-encoding on your encrypted text. If you could tell us more about where the % is and how you got that string, that would help a lot.

(As an aside, you should use using statements for all the streams etc, rather than explicitly closing them; also your try/catch is somewhat pointless. Those are side issues though.)