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RSAPKCS1KeyExchangeFormatter Class

Creates the PKCS#1 key exchange data using RSA.

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

[ComVisibleAttribute(true)] 
public class RSAPKCS1KeyExchangeFormatter : AsymmetricKeyExchangeFormatter
/** @attribute ComVisibleAttribute(true) */ 
public class RSAPKCS1KeyExchangeFormatter extends AsymmetricKeyExchangeFormatter
ComVisibleAttribute(true) 
public class RSAPKCS1KeyExchangeFormatter extends AsymmetricKeyExchangeFormatter

Key exchange allows a sender to create secret information (such as random data that can be used as a key in a symmetric encryption algorithm) and use encryption to send it to the intended recipient.

Use RSAPKCS1KeyExchangeDeformatter to receive the key exchange and extract the secret information from it.

Caution noteCaution

It is highly recommended that you not attempt to create your own key exchange method from the basic functionality provided, because many details of the operation must be performed carefully in order for the key exchange to be successful.

The following code example demonstrates how to use members of the RSAPKCS1KeyExchangeFormatter class.

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

class RSAEncoder
{
    // Use a member variable to hold the RSA key for encoding and decoding.
    private RSA rsaKey;

    [STAThread]
    static void Main(string[] args)
    {
        string message = "A phrase to be encoded.";

        RSAEncoder rsaEncoder = new RSAEncoder();
        rsaEncoder.InitializeKey(RSA.Create());

        Console.WriteLine("Encoding the following message:");
        Console.WriteLine(message);
        byte[] encodedMessage = rsaEncoder.EncodeMessage(message);
        Console.WriteLine("Resulting message encoded:");
        Console.WriteLine(Encoding.ASCII.GetString(encodedMessage));

        string decodedMessage = rsaEncoder.DecodeMessage(encodedMessage);
        Console.WriteLine("Resulting message decoded:");
        Console.WriteLine(decodedMessage);

        // Construct a formatter to demonstrate how to set each property.
        rsaEncoder.ConstructFormatter();

        // Construct a deformatter to demonstrate how to set each property.
        rsaEncoder.ConstructDeformatter();

        Console.WriteLine("This sample completed successfully; " + 
            "press Enter to exit.");
        Console.ReadLine();
    }

    // Initialize an rsaKey member variable with the specified RSA key.
    private void InitializeKey(RSA key)
    {
        rsaKey = key;
    }

    // Use the RSAPKCS1KeyExchangeDeformatter class to decode the 
    // specified message.
    private byte[] EncodeMessage(string message)
    {
        byte[] encodedMessage = null;

        try
        {
            // Construct a formatter with the specified RSA key.
            RSAPKCS1KeyExchangeFormatter keyEncryptor =
                new RSAPKCS1KeyExchangeFormatter(rsaKey);

            // Convert the message to bytes to create the encrypted data.
            byte[] byteMessage = Encoding.ASCII.GetBytes(message);
            encodedMessage = keyEncryptor.CreateKeyExchange(byteMessage);
        }
        catch (Exception ex)
        {
            Console.WriteLine("Unexpected exception caught:" + ex.ToString());
        }

        return encodedMessage;
    }

    // Use the RSAPKCS1KeyExchangeDeformatter class to decode the
    // specified message.
    private string DecodeMessage(byte[] encodedMessage)
    {
        string decodedMessage = null;

        try
        {
            // Construct a deformatter with the specified RSA key.
            RSAPKCS1KeyExchangeDeformatter keyDecryptor =
                new RSAPKCS1KeyExchangeDeformatter(rsaKey);

            // Decrypt the encoded message.
            byte[] decodedBytes =
                keyDecryptor.DecryptKeyExchange(encodedMessage);

            // Retrieve a string representation of the decoded message.
            decodedMessage = Encoding.ASCII.GetString(decodedBytes);
        }
        catch (Exception ex)
        {
            Console.WriteLine("Unexpected exception caught:" + ex.ToString());
        }

        return decodedMessage;
    }

    // Create an RSAPKCS1KeyExchangeFormatter object with a new RSA key.
    // Display its properties to the console.
    private void ConstructFormatter()
    {
        // Construct an empty Optimal Asymmetric Encryption Padding (OAEP)
        // key exchange.
        RSAPKCS1KeyExchangeFormatter rsaFormatter =
            new RSAPKCS1KeyExchangeFormatter();

        // Create an RSAKey and set it into the specified 
        // RSAPKCS1KeyExchangeFormatter.
        RSA key = RSA.Create();
        rsaFormatter.SetKey(key);

        // Create a random number using RNGCryptoServiceProvider.
        RNGCryptoServiceProvider ring = new RNGCryptoServiceProvider(); 
        rsaFormatter.Rng = ring;

        Console.WriteLine();
        Console.WriteLine("**" + rsaFormatter.ToString() + "**");
        Console.Write("The following random number was generated using the ");
        Console.WriteLine("class:");
        Console.WriteLine(rsaFormatter.Rng);

        string xmlParameters = rsaFormatter.Parameters;

        Console.WriteLine();
        Console.WriteLine("The RSA formatter has the following parameters:");
        Console.WriteLine(rsaFormatter.Parameters);
    }

    // Create an RSAPKCS1KeyExchangeDeformatter object with a new RSA key.
    // Display its properties to the console.
    private void ConstructDeformatter()
    {
        // Construct an empty OAEP key exchange.
        RSAPKCS1KeyExchangeDeformatter rsaDeformatter = 
            new RSAPKCS1KeyExchangeDeformatter();

        // Create an RSAKey and set it into the specified 
        // RSAPKCS1KeyExchangeFormatter.
        RSA key = RSA.Create();
        rsaDeformatter.SetKey(key);

        RNGCryptoServiceProvider ring = new RNGCryptoServiceProvider(); 
        rsaDeformatter.RNG = ring;

        Console.WriteLine();
        Console.WriteLine("**" + rsaDeformatter.ToString() + "**");

        string xmlParameters = rsaDeformatter.Parameters;

        Console.WriteLine();
        Console.WriteLine("The RSA deformatter has the following ");
        Console.WriteLine("parameters:" + xmlParameters);
    }
}

import System.*;
import System.Security.Cryptography.*;
import System.Text.*;

class RSAEncoder
{
    // Use a member variable to hold the RSA key for encoding and decoding.
    private RSA rsaKey;

    /** @attribute STAThread()
     */
    public static void main(String[] args)
    {
        String message = "A phrase to be encoded.";

        RSAEncoder rsaEncoder = new RSAEncoder();
        rsaEncoder.InitializeKey(RSA.Create());

        Console.WriteLine("Encoding the following message:");
        Console.WriteLine(message);
        ubyte encodedMessage[] = rsaEncoder.EncodeMessage(message);
        Console.WriteLine("Resulting message encoded:");
        Console.WriteLine(Encoding.get_ASCII().GetString(encodedMessage));

        String decodedMessage = rsaEncoder.DecodeMessage(encodedMessage);
        Console.WriteLine("Resulting message decoded:");
        Console.WriteLine(decodedMessage);
        // Construct a formatter to demonstrate how to set each property.
        rsaEncoder.ConstructFormatter();
        // Construct a deformatter to demonstrate how to set each property.
        rsaEncoder.ConstructDeformatter();

        Console.WriteLine("This sample completed successfully; " 
            + "press Enter to exit.");
        Console.ReadLine();
    } //main

    // Initialize an rsaKey member variable with the specified RSA key.
    private void InitializeKey(RSA key)
    {
        rsaKey = key;
    } //InitializeKey

    // Use the RSAPKCS1KeyExchangeDeformatter class to decode the 
    // specified message.
    private ubyte[] EncodeMessage(String message)
    {
        ubyte encodedMessage[] = null;
        try {
            // Construct a formatter with the specified RSA key.
            RSAPKCS1KeyExchangeFormatter keyEncryptor 
                = new RSAPKCS1KeyExchangeFormatter(rsaKey);

            // Convert the message to bytes to create the encrypted data.
            ubyte byteMessage[] = Encoding.get_ASCII().GetBytes(message);
            encodedMessage = keyEncryptor.CreateKeyExchange(byteMessage);
        } 
        catch (System.Exception ex) {
            Console.WriteLine("Unexpected exception caught:" + ex.ToString());
        }
        return encodedMessage;
    } //EncodeMessage

    // Use the RSAPKCS1KeyExchangeDeformatter class to decode the
    // specified message.
    private String DecodeMessage(ubyte encodedMessage[])
    {
        String decodedMessage = null;
        try {
            // Construct a deformatter with the specified RSA key.
            RSAPKCS1KeyExchangeDeformatter keyDecryptor 
                = new RSAPKCS1KeyExchangeDeformatter(rsaKey);

            // Decrypt the encoded message.
            ubyte decodedBytes[] = keyDecryptor.
                DecryptKeyExchange(encodedMessage);

            // Retrieve a string representation of the decoded message.
            decodedMessage = Encoding.get_ASCII().GetString(decodedBytes);
        }
        catch (System.Exception ex) {
            Console.WriteLine("Unexpected exception caught:" 
                + ex.ToString());
        }
        return decodedMessage;
    } //DecodeMessage

    // Create an RSAPKCS1KeyExchangeFormatter object with a new RSA key.
    // Display its properties to the console.
    private void ConstructFormatter()
    {
        // Construct an empty Optimal Asymmetric Encryption Padding (OAEP)
        // key exchange.
        RSAPKCS1KeyExchangeFormatter rsaFormatter 
            = new RSAPKCS1KeyExchangeFormatter();

        // Create an RSAKey and set it into the specified 
        // RSAPKCS1KeyExchangeFormatter.
        RSA key = RSA.Create();
        rsaFormatter.SetKey(key);

        // Create a random number using RNGCryptoServiceProvider.
        RNGCryptoServiceProvider ring = new RNGCryptoServiceProvider();
        rsaFormatter.set_Rng(ring);

        Console.WriteLine();
        Console.WriteLine("**" + rsaFormatter.ToString() + "**");
        Console.Write("The following random number was generated using the ");
        Console.WriteLine("class:");
        Console.WriteLine(rsaFormatter.get_Rng());
        String xmlParameters = rsaFormatter.get_Parameters();

        Console.WriteLine();
        Console.WriteLine("The RSA formatter has the following parameters:");
        Console.WriteLine(rsaFormatter.get_Parameters());
    } //ConstructFormatter

    // Create an RSAPKCS1KeyExchangeDeformatter object with a new RSA key.
    // Display its properties to the console.
    private void ConstructDeformatter()
    {
        // Construct an empty OAEP key exchange.
        RSAPKCS1KeyExchangeDeformatter rsaDeformatter 
            = new RSAPKCS1KeyExchangeDeformatter();

        // Create an RSAKey and set it into the specified 
        // RSAPKCS1KeyExchangeFormatter.
        RSA key = RSA.Create();
        rsaDeformatter.SetKey(key);

        RNGCryptoServiceProvider ring = new RNGCryptoServiceProvider();
        rsaDeformatter.set_RNG(ring);

        Console.WriteLine();
        Console.WriteLine("**" + rsaDeformatter.ToString() + "**");
        String xmlParameters = rsaDeformatter.get_Parameters();

        Console.WriteLine();
        Console.WriteLine("The RSA deformatter has the following ");
        Console.WriteLine("parameters:" + xmlParameters);
    } //ConstructDeformatter
} //RSAEncoder

System.Object
   System.Security.Cryptography.AsymmetricKeyExchangeFormatter
    System.Security.Cryptography.RSAPKCS1KeyExchangeFormatter
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

.NET Framework

Supported in: 2.0, 1.1, 1.0

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