Error:"Key not valid for use in specified state" for "RSACryptoServi ceProvider.Encr ypt()"

[Ismail Fatih Yýldýrým]

I modified the RSACSPSample from MSDN to try out a simple commutative
encryption model using RSA encryption but when i run the progrem the first
encryption command works but during the second encryption command (line :
encryptedData2 = RSAE...) i get a "Key not valid for use in specified
state." exception error even though i provide a valid second key to encrypt
it. How can i overcome this error and get double encryption to work ?

The Code I use :
############### ############### ############### ############### ############### ############### ##

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

class RSATest
{

static void Main()
{
try
{
//Create a UnicodeEncoder to convert between byte array and
string.
UnicodeEncoding ByteConverter = new UnicodeEncoding ();

//Create byte arrays to hold original, encrypted, and decrypted
data.
byte[] dataToEncrypt = ByteConverter.G etBytes("Data to
Encrypt");
byte[] encryptedData;
byte[] encryptedData2;
byte[] decryptedData;

//Create a new instances of RSACryptoServic eProvider
RSACryptoServic eProvider RSA = new RSACryptoServic eProvider();
RSACryptoServic eProvider RSA2 = new RSACryptoServic eProvider();
//Pass the data to ENCRYPT, the public key information
encryptedData = RSAEncrypt(data ToEncrypt,
RSA.ExportParam eters(false), false);
encryptedData2 = RSAEncrypt(encr yptedData,
RSA2.ExportPara meters(false), false);

//Pass the data to DECRYPT using private key information

decryptedData = RSADecrypt(encr yptedData2,
RSA.ExportParam eters(true), false);

decryptedData = RSADecrypt(decr yptedData,
RSA2.ExportPara meters(true), false);

//Display the decrypted plaintext to the console.
Console.WriteLi ne("Decrypted plaintext: {0}",
ByteConverter.G etString(decryp tedData));
}
catch (Exception ex)
{
//Catch this exception in case the encryption did
//not succeed.
Console.WriteLi ne(ex.Message);

}
}

static public byte[] RSAEncrypt(byte[] DataToEncrypt, RSAParameters
RSAKeyInfo, bool DoOAEPPadding)
{
try
{
//Create a new instance of RSACryptoServic eProvider.
RSACryptoServic eProvider RSA = new RSACryptoServic eProvider();

//Import the RSA Key information.
RSA.ImportParam eters(RSAKeyInf o);

//Encrypt the passed byte array and specify OAEP padding.
return RSA.Encrypt(Dat aToEncrypt, DoOAEPPadding);
}
//Catch and display a CryptographicEx ception
//to the console.
catch (CryptographicE xception e)
{
Console.WriteLi ne(e.Message);

return null;
}

}

static public byte[] RSADecrypt(byte[] DataToDecrypt, RSAParameters
RSAKeyInfo, bool DoOAEPPadding)
{
try
{
//Create a new instance of RSACryptoServic eProvider.
RSACryptoServic eProvider RSA = new RSACryptoServic eProvider();

//Import the RSA Key information. This needs
RSA.ImportParam eters(RSAKeyInf o);

//Decrypt the passed byte array and specify OAEP padding.

return RSA.Decrypt(Dat aToDecrypt, DoOAEPPadding);
}
//Catch and display a CryptographicEx ception

catch (CryptographicE xception e)
{
Console.WriteLi ne(e.ToString() );

return null;
}

}
}