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RSACryptoServiceProvider.Encrypt Method

Encrypts data with the RSA algorithm.

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

'Declaration
Public Function Encrypt ( _
	rgb As Byte(), _
	fOAEP As Boolean _
) As Byte()

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 Nothing.

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.

Imports System
Imports System.Security.Cryptography

Class RSACSPSample

    Shared Sub Main()
        Try 
            'initialze the byte arrays to the public key information. 
            Dim PublicKey As Byte() = {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}

            Dim Exponent As Byte() = {1, 0, 1}

            'Values to store encrypted symmetric keys. 
            Dim EncryptedSymmetricKey() As Byte 
            Dim EncryptedSymmetricIV() As Byte 

            'Create a new instance of RSACryptoServiceProvider. 
            Dim RSA As New RSACryptoServiceProvider()

            'Create a new instance of RSAParameters. 
            Dim RSAKeyInfo As 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. 
            Dim RM As 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 e As CryptographicException
            Console.WriteLine(e.Message)
        End Try 
    End Sub 
End Class

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8
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