C # using RSA certificate file encryption and decryption examples

Modify the example on MSDN so that it can be encrypted and decrypted through the RSA certificate file, and encounter a minor problem in the middle.

Q: When executing the Exportparameters () method, the return Cryptographicexception: The item is not suitable to be used in a specified state (key is not valid for using in specified).

A: When you import a certificate with a private key, you need to mark "private key exportable" with the "x509keystorageflags" parameter.

X509Certificate2 prvcrt = new X509Certificate2 (@ "X:\path\to\CA.pfx", "***password***", X509keystorageflags.exportable);

The following is an example program:

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 Unicodeen                Coder 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 ())//{//consol E.writeline (RSA.                    Toxmlstring (false)); Pass the data to ENCRYPT, the public key information//(using Rsacryptoserviceprovider.exportparamet                    ERs (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.exportparame TERS (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 inf Ormation.                    This is needs//toinclude the public key information. Rsa.                    ImportParameters (Rsakeyinfo);                      Encrypt the passed byte array and specify OAEP padding.                      OAEP padding is a 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 a 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; }        }    }}

　　

C # using RSA certificate file encryption and decryption examples