Invalid length for a Base-64 char array+RijndaelManaged/Encryption

I am playing with Encryption/Decryption. and its good experience. Actually i have to encrypt a Guid and have to pass it in Querystring and have to get that Querystring and again have to decrypt data based on Querystring so i will get my origianal GUI.

First My Code looks like this:

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Security.Cryptography;
namespace RfcDemoPwdGenerator
{
class Helper
{
private static string password = “ABC”;
private static int iterations = 1024;
private static byte[] salt = Encoding.ASCII.GetBytes(“This is My Salt value”);
/// <summary>
/// this function will take a plaintext as an arg and
/// returns ciphertext as an O/P
/// </summary>
/// <param name=”plaintext”></param>
/// <returns></returns>
public static string Encrypt(string plaintext)
{
Rfc2898DeriveBytes KeyBytes = new Rfc2898DeriveBytes(password, salt, iterations);
//The deafault iteration count is 1000
RijndaelManaged alg = new RijndaelManaged();
alg.Key = KeyBytes.GetBytes(32);
alg.IV = KeyBytes.GetBytes(16);
MemoryStream encryptStream = new MemoryStream();
//Stream to write
CryptoStream encrypt = new CryptoStream(encryptStream, alg.CreateEncryptor(), CryptoStreamMode.Write);
//convert plain text to byte array
byte[] data = Encoding.UTF8.GetBytes(plaintext);
encrypt.Write(data, 0, data.Length); //data to encrypt,start,stop
encrypt.FlushFinalBlock();//Clear buffer
encrypt.Close();
return Convert.ToBase64String(encryptStream.ToArray());//return encrypted data
}

/// <summary>
/// this function will take a ciphertext as an arg and
/// returns plaintext as an O/P
/// </summary>
/// <param name=”plaintext”></param>
/// <returns></returns>
public static string Decrypt(string ciphertext)
{
Rfc2898DeriveBytes KeyBytes = new Rfc2898DeriveBytes(password, salt, iterations);
//The deafault iteration count is 1000
RijndaelManaged alg = new RijndaelManaged();
alg.Key = KeyBytes.GetBytes(32);
alg.IV = KeyBytes.GetBytes(16);
MemoryStream decryptStream = new MemoryStream();
//Stream to read
CryptoStream decrypt = new CryptoStream(decryptStream, alg.CreateDecryptor(), CryptoStreamMode.Write);
//convert plain text to byte array
byte[] data = Convert.FromBase64String(ciphertext); //This guy was throwing an error Invalid length for a Base-64 char array
decrypt.Write(data, 0, data.Length); //data to encrypt,start,stop
decrypt.Flush();
decrypt.Close();
return Encoding.UTF8.GetString(decryptStream.ToArray());//return PlainText
}
}
}

Solution

Why this Error?

Sometime it works fine and sometime it fails. It made me frustrated..googled it too..then also .

so started noting down Plaintext,URL String,Cipher text and at last got the solution and root of problem. getting excited to know it..here it is…

*********THE SOLUTION**********
Plain Text[My guid] = 72e3f882-9e0e-434f-bf51-28cffc1903c1
Cipher TEXT[generatd by my Encrypt block] = 5NGETiEwyYy3F+P+QnzkRUeB5l7xUTRJuhhGZmFwi5WxCfeo3+kCvTs0z9s+CnZW
Querystring[encrypted guid] = 5NGETiEwyYy3F P QnzkRUeB5l7xUTRJuhhGZmFwi5WxCfeo3 kCvTs0z9s CnZW

Have you seen the change in Querystring???

My Cipher contains “+” and when i pass it in Querystring it ” ” it passes[space]…

That’s the solution dude….

so for solving it just have to change the following block of Decrypt string

byte[] data = Convert.FromBase64String(ciphertext); //OLD ONE

byte[] data = Convert.FromBase64String(ciphertext.Replace(” “,”+”)); //NEW ONE
Hope it wiill save your time which i had wasted/invested…

Happy Encrypting/Decrypting!!!

Resource: http://blogs.msdn.com/shawnfa/archive/2005/11/10/491431.aspx

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