SymmetricAlgorithmEvaluator.cs

using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;

namespace APress.DotNetSecurity.Chapter2.SymmetricAlgorithmEvaluator
{
 class SymmetricAlgorithmEvaluatorTester
 {
  static void Main(string[] args)
  {
   try
   {
    Console.WriteLine("Creating a RijndaelManaged instance...");
    SymmetricAlgorithm symAlg = new RijndaelManaged();
    
    symAlg.GenerateIV();
    Console.WriteLine("Generated IV value is " +
     ArrayToHexString(symAlg.IV));

    Console.WriteLine("Block size is " + symAlg.BlockSize.ToString());
    Console.WriteLine("Key size is " + symAlg.KeySize.ToString());
    Console.WriteLine("Key value is " +
     ArrayToHexString(symAlg.Key));

    foreach(KeySizes ks in symAlg.LegalKeySizes)
    {
     int currentSize = ks.MinSize;

     do
     {
      Console.WriteLine("Legal key size:  " + currentSize.ToString());
      currentSize += ks.SkipSize;
     } while(currentSize <= ks.MaxSize);
    }

    Console.WriteLine("Mode is " + symAlg.Mode.ToString());
    Console.WriteLine("Padding type is " + symAlg.Padding.ToString());

    Console.WriteLine("Input the desired key size:");
    int desiredKeySize = Int32.Parse(Console.ReadLine());
    KeySizesEx kse = new KeySizesEx(symAlg.LegalKeySizes);
    
    if(true == kse.IsValidKeySize(desiredKeySize))
    {
     Console.WriteLine(desiredKeySize.ToString() +
      " is a valid key size.");
    }
    else
    {
     Console.WriteLine(desiredKeySize.ToString() +
      " is NOT a valid key size.");
    }
   }
   catch(CryptographicUnexpectedOperationException cuoe)
   {
    Console.WriteLine("CryptographicUnexpectedOperationException:  "
     + cuoe.Message);
    Console.WriteLine(cuoe.StackTrace);
   }
   catch(CryptographicException ce)
   {
    Console.WriteLine("CryptographicException:  " + ce.Message);
    Console.WriteLine(ce.StackTrace);
   }
   catch(Exception ge)
   {
    Console.WriteLine("Exception:  " + ge.GetType().Name + " " + ge.Message);
    Console.WriteLine(ge.StackTrace);
   }
   finally
   {
    Console.WriteLine("Press the return key to continue...");
    Console.Read();
   }
  }
  private static String ArrayToHexString(byte[] ByteData)
  {
   StringBuilder retVal = new StringBuilder();
   
   foreach(byte b in ByteData)
   {
    retVal.Append(b.ToString("X2"));
    retVal.Append(" ");
   }
   retVal.Remove(retVal.Length - 1, 1);

   return retVal.ToString();
  } 
 }

 public class KeySizesEx
 {
  private KeySizes[] ks = null;

  public KeySizesEx(KeySizes[] ks)
  {
   this.ks = ks;
  }

  public bool IsValidKeySize(int DesiredSize)
  {
   bool retVal = false;

   foreach(KeySizes keySize in ks)
   {
    if(DesiredSize >= keySize.MinSize &&
     DesiredSize <= keySize.MaxSize &&
     (DesiredSize % keySize.SkipSize) == 0)
    {
     retVal = true;
     break;
    }
   }

   return retVal;
  }
 }
}