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RSACryptoServiceProvider.Encrypt Method

Encrypts data with the RSA algorithm.

Namespace:  System.Security.Cryptography
Assembly:  mscorlib (in mscorlib.dll)
public byte[] Encrypt(
	byte[] rgb,
	bool fOAEP
)

Parameters

rgb
Type: System.Byte[]

The data to be encrypted.

fOAEP
Type: System.Boolean

true to perform direct RSA encryption using OAEP padding (only available on a computer running Microsoft Windows XP or later); otherwise, false to use PKCS#1 v1.5 padding.

Return Value

Type: System.Byte[]
The encrypted data.
ExceptionCondition
CryptographicException

The cryptographic service provider (CSP) cannot be acquired.

-or-

The length of the rgb parameter is greater than the maximum allowed length.

-or-

The fOAEP parameter is true and OAEP padding is not supported.

ArgumentNullException

rgb is null.

The following table describes the padding supported by different versions of Microsoft Windows and the maximum length of rgb allowed by the different combinations of operating systems and padding.

Padding

Operating System Supported

Maximum Length of rgb Parameter

OAEP padding (PKCS#1 v2)

Microsoft Windows XP or later.

Modulus size -2 -2*hLen, where hLen is the size of the hash.

Direct Encryption (PKCS#1 v1.5)

Microsoft Windows 2000 or later with the high encryption pack installed.

Modulus size - 11. (11 bytes is the minimum padding possible.)

Direct Encryption and OAEP padding not supported

Microsoft Windows 98, Microsoft Windows Millennium, or Windows 2000 or later without the high encryption pack installed.

The maximum size allowed for a symmetric key.

Use Decrypt to decrypt the results of this method.

The following code example initializes an RSACryptoServiceProvider object to the value of a public key (sent by another party), generates a session key using the RijndaelManaged algorithm, and then encrypts the session key using the RSACryptoServiceProvider object. Using this scheme, the session key could be sent back to the owner of the private RSA key and the two parties could use the session key to exchange encrypted data.

using System;
using System.Security.Cryptography;

class RSACSPSample
{

	static void Main()
	{
		try
		{		//initialze the byte arrays to the public key information. 
			byte[] PublicKey = {214,46,220,83,160,73,40,39,201,155,19,202,3,11,191,178,56,
								   74,90,36,248,103,18,144,170,163,145,87,54,61,34,220,222,
								   207,137,149,173,14,92,120,206,222,158,28,40,24,30,16,175,
								   108,128,35,230,118,40,121,113,125,216,130,11,24,90,48,194,
								   240,105,44,76,34,57,249,228,125,80,38,9,136,29,117,207,139,
								   168,181,85,137,126,10,126,242,120,247,121,8,100,12,201,171,
								   38,226,193,180,190,117,177,87,143,242,213,11,44,180,113,93,
								   106,99,179,68,175,211,164,116,64,148,226,254,172,147};

			byte[] Exponent = {1,0,1};

			//Values to store encrypted symmetric keys. 
			byte[] EncryptedSymmetricKey;
			byte[] EncryptedSymmetricIV;

			//Create a new instance of RSACryptoServiceProvider.
			RSACryptoServiceProvider RSA = new RSACryptoServiceProvider();

			//Create a new instance of RSAParameters.
			RSAParameters RSAKeyInfo = new RSAParameters();

			//Set RSAKeyInfo to the public key values. 
			RSAKeyInfo.Modulus = PublicKey;
			RSAKeyInfo.Exponent = Exponent;

			//Import key parameters into RSA.
			RSA.ImportParameters(RSAKeyInfo);

			//Create a new instance of the RijndaelManaged class.
			RijndaelManaged RM = new RijndaelManaged();

			//Encrypt the symmetric key and IV.
			EncryptedSymmetricKey = RSA.Encrypt(RM.Key, false);
			EncryptedSymmetricIV = RSA.Encrypt(RM.IV, false);

			Console.WriteLine("RijndaelManaged Key and IV have been encrypted with RSACryptoServiceProvider."); 
		
		}
		//Catch and display a CryptographicException   
		//to the console. 
		catch(CryptographicException e)
		{
			Console.WriteLine(e.Message);
		}
	}
}

.NET Framework

Supported in: 4.5.1, 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 8, Silverlight 8.1

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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