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RSACryptoServiceProvider Constructor

Initializes a new instance of the RSACryptoServiceProvider class using the default key.

Namespace:  System.Security.Cryptography
Assembly:  mscorlib (in mscorlib.dll)

public RSACryptoServiceProvider()

ExceptionCondition
CryptographicException

The cryptographic service provider (CSP) cannot be acquired.

If no default key is found, a new key is created.

This constructor creates an Exchange key pair suitable to encrypt session keys so that they can be safely stored and exchanged with other users. The generated key corresponds to a key generated using the AT_KEYEXCHANGE value used in the unmanaged Microsoft Cryptographic API (CAPI).

The following code example uses the RSACryptoServiceProvider class to encrypt a string into an array of bytes and then decrypt the bytes back into a string.

using System;
using System.Security.Cryptography;
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;

            //Create a new instance of RSACryptoServiceProvider to generate 
            //public and private key data. 
            using (RSACryptoServiceProvider RSA = new RSACryptoServiceProvider())
            {

                //Pass the data to ENCRYPT, the public key information  
                //(using RSACryptoServiceProvider.ExportParameters(false), 
                //and a boolean flag specifying no OAEP padding.
                encryptedData = RSAEncrypt(dataToEncrypt, RSA.ExportParameters(false), false);

                //Pass the data to DECRYPT, the private key information  
                //(using RSACryptoServiceProvider.ExportParameters(true), 
                //and a boolean flag specifying no OAEP padding.
                decryptedData = RSADecrypt(encryptedData, RSA.ExportParameters(true), false);

                //Display the decrypted plaintext to the console. 
                Console.WriteLine("Decrypted plaintext: {0}", ByteConverter.GetString(decryptedData));
            }
        }
        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;
        }

    }
}

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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