RSACryptoServiceProvider

[KDavie]

Hello,

I'm trying to work through the following example:

http://www.eggheadcafe.com/articles/20020630.asp

Here is what my Cryptography class looks like:

using System;
using System.Collections.Generic;
using System.Text;
using System.Security.Cryptography;

namespace Rijndael
{
    class RSAWrapper 
    {
        private string _pubk;
        public string pubk
        {
            get { return _pubk; }
            set { _pubk = value; }
        }
        private string _prik;
        public string prik
        {
            get { return _prik; }
            set { _prik = value; }
        }
        public RSAWrapper()
        {
            CspParameters param = new CspParameters();
            param.Flags = CspProviderFlags.UseMachineKeyStore;
            RSACryptoServiceProvider RSA = new RSACryptoServiceProvider(param);
            pubk = RSA.ToXmlString(false);
            prik = RSA.ToXmlString(true);

        }
        public string CipherText(string plainText, string xmlString)
        {
            RSACryptoServiceProvider RSA = new RSACryptoServiceProvider();
            RSA.FromXmlString(xmlString);
            byte[] encryptedStringAsByte = RSA.Encrypt(System.Text.Encoding.Unicode.GetBytes(plainText),false);
            string encryptedStringAsString = System.Text.Encoding.Unicode.GetString(encryptedStringAsByte);
            return encryptedStringAsString;
        }
        public string DecipherText(string cipherText, string xmlString)
        {
            RSACryptoServiceProvider RSA = new RSACryptoServiceProvider();
            RSA.FromXmlString(xmlString);
            byte[] decryptedStringAsByte = RSA.Decrypt(System.Text.Encoding.Unicode.GetBytes(cipherText), false);
            string decryptedStringAsString = System.Text.Encoding.Unicode.GetString(decryptedStringAsByte);
            return decryptedStringAsString;
        }
        
      
    }
}

I have a form I'm using to test this which contains a series of text-boxes and buttons. The first button creates a public and private key and displays them in their respective text-boxes (txtPub, txtPriv). The second button encrypts the data by passing in the text to be encrypted and the private key to CipherText() and then diplays it in a text-box (txtCipher). The third button decrypts the string by passing it in along with the public key value to DecipherText(). The problem is when I try to decipher the text I get an exception with a message that says "bad key."

Any ideas?

-Kevin

Kevin Davie
Consultant
Sogeti USA

http://www.us.sogeti.com