C # example of encryption and decryption using RSA certificate files

Modify the example on MSDN so that it can be encrypted and decrypted through the RSA Certificate file. A small problem occurs in the middle.

Q: When the ExportParameters () method is executed, return CryptographicException: This item is not suitable for use in the specified state (Key not valid for use in specified state ).

A: When importing A certificate with A private key, you need to use"X509KeyStorageFlags"Parameter mark" private key can be exported ".

X509Certificate2 prvcrt = new X509Certificate2 (@ "X: \ path \ to \ CA. pfx", "*** password ***", X509KeyStorageFlags. Exportable);

The following is an example program:

View Code

using System;using System.Collections.Generic;using System.Linq;using System.Text;namespace TeatApp_Crypto{    using System;    using System.Security.Cryptography;    using System.Security.Cryptography.X509Certificates;    using System.Text;    class RSACSPSample    {        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.GetBytes("Data to Encrypt");                byte[] encryptedData;                byte[] decryptedData;                X509Certificate2 pubcrt = new X509Certificate2(@"X:\path\to\CA.crt");                RSACryptoServiceProvider pubkey = (RSACryptoServiceProvider)pubcrt.PublicKey.Key;                X509Certificate2 prvcrt = new X509Certificate2(@"X:\path\to\CA.pfx", "***password***", X509KeyStorageFlags.Exportable);                RSACryptoServiceProvider prvkey = (RSACryptoServiceProvider)prvcrt.PrivateKey;                //Create a new instance of RSACryptoServiceProvider to generate                //public and private key data.                //using (RSACryptoServiceProvider RSA = new RSACryptoServiceProvider())                //{                    //Console.WriteLine(RSA.ToXmlString(false));                    //Pass the data to ENCRYPT, the public key information                     //(using RSACryptoServiceProvider.ExportParameters(false),                    //and a boolean flag specifying no OAEP padding.                    encryptedData = RSAEncrypt(dataToEncrypt, pubkey.ExportParameters(false), false);                    Console.WriteLine("Encrypted plaintext: {0}", Convert.ToBase64String(encryptedData));                    //Pass the data to DECRYPT, the private key information                     //(using RSACryptoServiceProvider.ExportParameters(true),                    //and a boolean flag specifying no OAEP padding.                    decryptedData = RSADecrypt(encryptedData, prvkey.ExportParameters(true), false);                                         //Display the decrypted plaintext to the console.                     Console.WriteLine("Decrypted plaintext: {0}", ByteConverter.GetString(decryptedData));                //}                prvkey.Clear();                pubkey.Clear();                Console.Read();            }            catch (ArgumentNullException)            {                //Catch this exception in case the encryption did                //not succeed.                Console.WriteLine("Encryption failed.");            }        }        static public byte[] RSAEncrypt(byte[] DataToEncrypt, RSAParameters RSAKeyInfo, bool DoOAEPPadding)        {            try            {                byte[] encryptedData;                //Create a new instance of RSACryptoServiceProvider.                using (RSACryptoServiceProvider RSA = new RSACryptoServiceProvider())                {                    //Import the RSA Key information. This only needs                    //toinclude the public key information.                    RSA.ImportParameters(RSAKeyInfo);                    //Encrypt the passed byte array and specify OAEP padding.                      //OAEP padding is only available on Microsoft Windows XP or                    //later.                      encryptedData = RSA.Encrypt(DataToEncrypt, DoOAEPPadding);                }                return encryptedData;            }            //Catch and display a CryptographicException              //to the console.            catch (CryptographicException e)            {                Console.WriteLine(e.Message);                return null;            }        }        static public byte[] RSADecrypt(byte[] DataToDecrypt, RSAParameters RSAKeyInfo, bool DoOAEPPadding)        {            try            {                byte[] decryptedData;                //Create a new instance of RSACryptoServiceProvider.                using (RSACryptoServiceProvider RSA = new RSACryptoServiceProvider())                {                    //Import the RSA Key information. This needs                    //to include the private key information.                    RSA.ImportParameters(RSAKeyInfo);                    //Decrypt the passed byte array and specify OAEP padding.                      //OAEP padding is only available on Microsoft Windows XP or                    //later.                      decryptedData = RSA.Decrypt(DataToDecrypt, DoOAEPPadding);                }                return decryptedData;            }            //Catch and display a CryptographicException              //to the console.            catch (CryptographicException e)            {                Console.WriteLine(e.ToString());                return null;            }        }    }}