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RSACryptoServiceProvider Constructor (Int32)

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

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

public RSACryptoServiceProvider(
	int dwKeySize
)

Parameters

dwKeySize
Type: System.Int32

The size of the key to use in bits.

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 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
        {
            //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.  Pass an integer specifying a key- 
            //length of 2048.
            RSACryptoServiceProvider RSAalg = new RSACryptoServiceProvider(2048);

            //Display the key-legth to the console.
            Console.WriteLine("A new key pair of legth {0} was created", RSAalg.KeySize);

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

            //Import the RSA Key information. This only needs 
            //toinclude the public key information.
            RSAalg.ImportParameters(RSAKeyInfo);

            //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, RSAParameters RSAKeyInfo,bool DoOAEPPadding)
    {
        try
        {
            //Create a new instance of RSACryptoServiceProvider.
            RSACryptoServiceProvider RSAalg = new RSACryptoServiceProvider();

            //Import the RSA Key information. This needs 
            //to include the private key information.
            RSAalg.ImportParameters(RSAKeyInfo);

            //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;
        }

    }
}

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC

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

.NET Framework

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

.NET Compact Framework

Supported in: 3.5, 2.0

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