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RSACryptoServiceProvider Constructor (Int32, CspParameters)

Initializes a new instance of the RSACryptoServiceProvider class with the specified key size and parameters.

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

public RSACryptoServiceProvider (
	int dwKeySize,
	CspParameters parameters
)
public RSACryptoServiceProvider (
	int dwKeySize, 
	CspParameters parameters
)
public function RSACryptoServiceProvider (
	dwKeySize : int, 
	parameters : CspParameters
)

Parameters

dwKeySize

The size of the key to use in bits.

parameters

The parameters to be passed to the cryptographic service provider (CSP).

Exception typeCondition

CryptographicException

The CSP cannot be acquired.

-or-

The key cannot be created.

This constructor creates or reuses a key container specified using the KeyContainerName field of the parameters parameter.

By default, 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).

You can create a Signature key pair suitable for authenticating (digitally signed) messages or files by setting the KeyNumber field of the parameters parameter to the Signature value. This type of key corresponds to the AT_SIGNATURE value used in CAPI.

If you create an RSACryptoServiceProvider object with the Exchange value specified and then create another RSACryptoServiceProvider object with the Signature value specified, both keys will be placed in a single container if both objects specify the same key container name.

To create a key that is compatible with stong-name signing using the RSACryptoServiceProvider class, you must create a Signature key pair.

The following code example creates a RSACryptoServiceProvider, generates a new key, and stores it in a key container.

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

class RSACSPSample
{

    static void Main()
    {
        try
        {
            string KeyContainerName = "MyKeyContainer";

            //Create a new key and persist it in 
            //the key container.
            RSAPersistKeyInCSP(KeyContainerName);

            //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;

            //Pass the data to ENCRYPT, the name of the key container,
            //and a boolean flag specifying no OAEP padding.
            encryptedData = RSAEncrypt(dataToEncrypt,KeyContainerName, false);

            //Pass the data to DECRYPT, the name of the key container,
            //and a boolean flag specifying no OAEP padding.
            decryptedData = RSADecrypt(encryptedData,KeyContainerName, false);

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

            RSADeleteKeyInCSP(KeyContainerName);
        }
        catch(ArgumentNullException)
        {
            //Catch this exception in case the encryption did
            //not succeed.
            Console.WriteLine("Encryption failed.");

        }
    }

    public static void RSAPersistKeyInCSP(string ContainerName)
    {
        try
        {
            // Create a new instance of CspParameters.  Pass
            // 13 to specify a DSA container or 1 to specify
            // an RSA container.  The default is 1.
            CspParameters cspParams = new CspParameters();

            // Specify the container name using the passed variable.
            cspParams.KeyContainerName = ContainerName;

            //Create a new instance of RSACryptoServiceProvider to generate
            //a new key pair.  Pass the CspParameters class to persist the 
            //key in the container.  Pass an intger of 2048 to specify the 
            //key-size.
            RSACryptoServiceProvider RSAalg = new RSACryptoServiceProvider( 2048, cspParams);

            //Indicate that the key was persisted.
            Console.WriteLine("The RSA key with a key-size of {0} was persisted in the container, \"{1}\".", 
                              RSAalg.KeySize , ContainerName);
        }
        catch(CryptographicException e)
        {
            Console.WriteLine(e.Message);

        }
    }

    public static void RSADeleteKeyInCSP(string ContainerName)
    {
        try
        {
            // Create a new instance of CspParameters.  Pass
            // 13 to specify a DSA container or 1 to specify
            // an RSA container.  The default is 1.
            CspParameters cspParams = new CspParameters();

            // Specify the container name using the passed variable.
            cspParams.KeyContainerName = ContainerName;

            //Create a new instance of DSACryptoServiceProvider. 
            //Pass the CspParameters class to use the 
            //key in the container.
            RSACryptoServiceProvider RSAalg = new RSACryptoServiceProvider(cspParams);

            //Delete the key entry in the container.
            RSAalg.PersistKeyInCsp = false;

            //Call Clear to release resources and delete the key from the container.
            RSAalg.Clear();

            //Indicate that the key was persisted.
            Console.WriteLine("The RSA key was deleted from the container, \"{0}\".", ContainerName);
        }
        catch(CryptographicException e)
        {
            Console.WriteLine(e.Message);

        }
    }

    static public byte[] RSAEncrypt(byte[] DataToEncrypt, string ContainerName, bool DoOAEPPadding)
    {
        try
        {	
            // Create a new instance of CspParameters.  Pass
            // 13 to specify a DSA container or 1 to specify
            // an RSA container.  The default is 1.
            CspParameters cspParams = new CspParameters();

            // Specify the container name using the passed variable.
            cspParams.KeyContainerName = ContainerName;

            //Create a new instance of DSACryptoServiceProvider.
            //Pass the CspParameters class to use the key 
            //from the key in the container.
            RSACryptoServiceProvider RSAalg = new RSACryptoServiceProvider(cspParams);

            //Encrypt the passed byte array and specify OAEP padding.  
            //OAEP padding is only available on Microsoft Windows XP or
            //later.  
            return RSAalg.Encrypt(DataToEncrypt, DoOAEPPadding);
        }
            //Catch and display a CryptographicException  
            //to the console.
        catch(CryptographicException e)
        {
            Console.WriteLine(e.Message);

            return null;
        }

    }

    static public byte[] RSADecrypt(byte[] DataToDecrypt, string ContainerName, bool DoOAEPPadding)
    {
        try
        {
            // Create a new instance of CspParameters.  Pass
            // 13 to specify a DSA container or 1 to specify
            // an RSA container.  The default is 1.
            CspParameters cspParams = new CspParameters();

            // Specify the container name using the passed variable.
            cspParams.KeyContainerName = ContainerName;

            //Create a new instance of DSACryptoServiceProvider.
            //Pass the CspParameters class to use the key 
            //from the key in the container.
            RSACryptoServiceProvider RSAalg = new RSACryptoServiceProvider(cspParams);

            //Decrypt the passed byte array and specify OAEP padding.  
            //OAEP padding is only available on Microsoft Windows XP or
            //later.  
            return RSAalg.Decrypt(DataToDecrypt, DoOAEPPadding);
        }
            //Catch and display a CryptographicException  
            //to the console.
        catch(CryptographicException e)
        {
            Console.WriteLine(e.ToString());

            return null;
        }

    }
}

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

class RSACSPSample
{
    public static void main(String[] args)
    {
        try {
            String keyContainerName = "MyKeyContainer";

            // Create a new key and persist it in 
            // the key container.
            RSAPersistKeyInCSP(keyContainerName);

            // Create a UnicodeEncoder to convert between byte array and string.
            UnicodeEncoding byteConverter = new UnicodeEncoding();

            // Create byte arrays to hold original, encrypted, and decrypted 
            // data.
            ubyte dataToEncrypt[] = byteConverter.GetBytes("Data to Encrypt");
            ubyte encryptedData[];
            ubyte decryptedData[];

            // Pass the data to ENCRYPT, the name of the key container,
            // and a boolean flag specifying no OAEP padding.
            encryptedData = RSAEncrypt(dataToEncrypt, keyContainerName, false);

            // Pass the data to DECRYPT, the name of the key container,
            // and a boolean flag specifying no OAEP padding.
            decryptedData = RSADecrypt(encryptedData, keyContainerName, false);

            // Display the decrypted plaintext to the console. 
            Console.WriteLine("Decrypted plaintext: {0}", 
                byteConverter.GetString(decryptedData));
            RSADeleteKeyInCSP(keyContainerName);
        }
        catch (ArgumentNullException exp) {
            // Catch this exception in case the encryption did
            // not succeed.
            Console.WriteLine("Encryption failed.");
        }
    } //main

    public static void RSAPersistKeyInCSP(String containerName)
    {
        try {
            // Create a new instance of CspParameters.  Pass
            // 13 to specify a DSA container or 1 to specify
            // an RSA container.  The default is 1.
            CspParameters cspParams = new CspParameters();

            // Specify the container name using the passed variable.
            cspParams.KeyContainerName = containerName;

            // Create a new instance of RSACryptoServiceProvider to generate
            // a new key pair.  Pass the CspParameters class to persist the 
            // key in the container.  Pass an intger of 2048 to specify the 
            // key-size.
            RSACryptoServiceProvider rsaAlg = 
                new RSACryptoServiceProvider(2048, cspParams);

            // Indicate that the key was persisted.
            Console.WriteLine("The RSA key with a key-size of {0} was "
                + "persisted in the container, \"{1}\".", 
                System.Convert.ToString(rsaAlg.get_KeySize()), containerName);
        }
        catch (CryptographicException e) {
            Console.WriteLine(e.get_Message());
        }
    } //RSAPersistKeyInCSP

    public static void RSADeleteKeyInCSP(String containerName)
    {
        try {
            // Create a new instance of CspParameters.  Pass
            // 13 to specify a DSA container or 1 to specify
            // an RSA container.  The default is 1.
            CspParameters cspParams = new CspParameters();

            // Specify the container name using the passed variable.
            cspParams.KeyContainerName = containerName;

            // Create a new instance of DSACryptoServiceProvider. 
            // Pass the CspParameters class to use the 
            // key in the container.
            RSACryptoServiceProvider rsaAlg = 
                new RSACryptoServiceProvider(cspParams);

            // Delete the key entry in the container.
            rsaAlg.set_PersistKeyInCsp(false);

            // Call Clear to release resources and delete the key from 
            // the container.
            rsaAlg.Clear();

            // Indicate that the key was persisted.
            Console.WriteLine("The RSA key was deleted from the container, "
                + "\"{0}\".", containerName);
        }
        catch (CryptographicException e) {
            Console.WriteLine(e.get_Message());
        }
    } //RSADeleteKeyInCSP

    public static ubyte[] RSAEncrypt(ubyte dataToEncrypt[], 
        String containerName, boolean doOAEPPadding)
    {
        try {
            // Create a new instance of CspParameters.  Pass
            // 13 to specify a DSA container or 1 to specify
            // an RSA container.  The default is 1.
            CspParameters cspParams = new CspParameters();

            // Specify the container name using the passed variable.
            cspParams.KeyContainerName = containerName;

            // Create a new instance of DSACryptoServiceProvider.
            // Pass the CspParameters class to use the key 
            // from the key in the container.
            RSACryptoServiceProvider rsaAlg = 
                new RSACryptoServiceProvider(cspParams);

            // Encrypt the passed byte array and specify OAEP padding.  
            // OAEP padding is only available on Microsoft Windows XP or
            // later.  
            return rsaAlg.Encrypt(dataToEncrypt, doOAEPPadding);
        }
        // Catch and display a CryptographicException  
        // to the console.
        catch (CryptographicException e) {
            Console.WriteLine(e.get_Message());
            return null;
        }
    } //RSAEncrypt

    public static ubyte[] RSADecrypt(ubyte[] dataToDecrypt, 
        String containerName, boolean doOAEPPadding)
    {
        try {
            // Create a new instance of CspParameters.  Pass
            // 13 to specify a DSA container or 1 to specify
            // an RSA container.  The default is 1.
            CspParameters cspParams = new CspParameters();

            // Specify the container name using the passed variable.
            cspParams.KeyContainerName = containerName;

            // Create a new instance of DSACryptoServiceProvider.
            // Pass the CspParameters class to use the key 
            // from the key in the container.
            RSACryptoServiceProvider rsaAlg = 
                new RSACryptoServiceProvider(cspParams);

            // Decrypt the passed byte array and specify OAEP padding.  
            // OAEP padding is only available on Microsoft Windows XP or
            // later.  
            return rsaAlg.Decrypt(dataToDecrypt, doOAEPPadding);
        }
        // Catch and display a CryptographicException  
        // to the console.
        catch (CryptographicException e) {
            Console.WriteLine(e.ToString());
            return null;
        }
    } //RSADecrypt
} //RSACSPSample

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, 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

.NET Compact Framework

Supported in: 2.0
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