RSAPKCS1KeyExchangeFormatter Class
Creates the PKCS#1 key exchange data using RSA.
Assembly: mscorlib (in mscorlib.dll)
System.Security.Cryptography.AsymmetricKeyExchangeFormatter
System.Security.Cryptography.RSAPKCS1KeyExchangeFormatter
| Name | Description | |
|---|---|---|
![]() | RSAPKCS1KeyExchangeFormatter() | Initializes a new instance of the RSAPKCS1KeyExchangeFormatter class. |
![]() | RSAPKCS1KeyExchangeFormatter(AsymmetricAlgorithm) | Initializes a new instance of the RSAPKCS1KeyExchangeFormatter class with the specified key. |
| Name | Description | |
|---|---|---|
![]() | Parameters | Gets the parameters for the PKCS #1 key exchange.(Overrides AsymmetricKeyExchangeFormatter.Parameters.) |
![]() | Rng | Gets or sets the random number generator algorithm to use in the creation of the key exchange. |
| Name | Description | |
|---|---|---|
![]() | CreateKeyExchange(Byte()) | Creates the encrypted key exchange data from the specified input data.(Overrides AsymmetricKeyExchangeFormatter.CreateKeyExchange(Byte()).) |
![]() | CreateKeyExchange(Byte(), Type) | Creates the encrypted key exchange data from the specified input data.(Overrides AsymmetricKeyExchangeFormatter.CreateKeyExchange(Byte(), Type).) |
![]() | Equals(Object) | Determines whether the specified object is equal to the current object.(Inherited from Object.) |
![]() | Finalize() | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.) |
![]() | GetHashCode() | Serves as the default hash function. (Inherited from Object.) |
![]() | GetType() | |
![]() | MemberwiseClone() | |
![]() | SetKey(AsymmetricAlgorithm) | Sets the public key to use for encrypting the key exchange data.(Overrides AsymmetricKeyExchangeFormatter.SetKey(AsymmetricAlgorithm).) |
![]() | ToString() | Returns a string that represents the current object.(Inherited from Object.) |
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 |
|---|
We recommend that you do 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 example shows how to use the RSAPKCS1KeyExchangeFormatter class to create an exchange key for a message recipient.
Imports System Imports System.IO Imports System.Security.Cryptography Imports System.Text Class Alice Public Shared Sub Main(ByVal args() As String) Dim bob As New Bob() Try Dim rsaKey As New RSACryptoServiceProvider() Try ' Get Bob's public key rsaKey.ImportCspBlob(bob.key) Dim encryptedSessionKey As Byte() = Nothing Dim encryptedMessage As Byte() = Nothing Dim iv As Byte() = Nothing Send(rsaKey, "Secret message", iv, encryptedSessionKey, encryptedMessage) bob.Receive(iv, encryptedSessionKey, encryptedMessage) Finally rsaKey.Dispose() End Try Finally bob.Dispose() End Try End Sub 'Main Private Shared Sub Send(ByVal key As RSA, ByVal secretMessage As String, ByRef iv() As Byte, ByRef encryptedSessionKey() As Byte, ByRef encryptedMessage() As Byte) Dim aes = New AesCryptoServiceProvider() Try iv = aes.IV ' Encrypt the session key Dim keyFormatter As New RSAPKCS1KeyExchangeFormatter(key) encryptedSessionKey = keyFormatter.CreateKeyExchange(aes.Key, GetType(Aes)) ' Encrypt the message Dim ciphertext As New MemoryStream() Try Dim cs As New CryptoStream(ciphertext, aes.CreateEncryptor(), CryptoStreamMode.Write) Try Dim plaintextMessage As Byte() = Encoding.UTF8.GetBytes(secretMessage) cs.Write(plaintextMessage, 0, plaintextMessage.Length) cs.Close() encryptedMessage = ciphertext.ToArray() Finally cs.Dispose() End Try Finally ciphertext.Dispose() End Try Finally aes.Dispose() End Try End Sub 'Send End Class 'Alice Public Class Bob Implements IDisposable Public key() As Byte Private rsaKey As New RSACryptoServiceProvider() Public Sub New() key = rsaKey.ExportCspBlob(False) End Sub 'NewNew Public Sub Receive(ByVal iv() As Byte, ByVal encryptedSessionKey() As Byte, ByVal encryptedMessage() As Byte) Dim aes = New AesCryptoServiceProvider() Try aes.IV = iv ' Decrypt the session key Dim keyDeformatter As New RSAPKCS1KeyExchangeDeformatter(rsaKey) aes.Key = keyDeformatter.DecryptKeyExchange(encryptedSessionKey) ' Decrypt the message Dim plaintext As New MemoryStream() Try Dim cs As New CryptoStream(plaintext, aes.CreateDecryptor(), CryptoStreamMode.Write) Try cs.Write(encryptedMessage, 0, encryptedMessage.Length) cs.Close() Dim message As String = Encoding.UTF8.GetString(plaintext.ToArray()) Console.WriteLine(message) Finally cs.Dispose() End Try Finally plaintext.Dispose() End Try Finally aes.Dispose() End Try End Sub 'Receive Public Overloads Sub Dispose() Implements IDisposable.Dispose rsaKey.Dispose() End Sub 'Dispose End Class 'Bob
Available since 1.1
Windows Phone Silverlight
Available since 7.1
Any public static ( Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.



