RSAOAEPKeyExchangeDeformatter Class
Updated: March 2011
Decrypts Optimal Asymmetric Encryption Padding (OAEP) key exchange data.
System.Security.Cryptography.AsymmetricKeyExchangeDeformatter
System.Security.Cryptography.RSAOAEPKeyExchangeDeformatter
Assembly: mscorlib (in mscorlib.dll)
The RSAOAEPKeyExchangeDeformatter type exposes the following members.
| Name | Description | |
|---|---|---|
![]() | RSAOAEPKeyExchangeDeformatter() | Initializes a new instance of the RSAOAEPKeyExchangeDeformatter class. |
![]() | RSAOAEPKeyExchangeDeformatter(AsymmetricAlgorithm) | Initializes a new instance of the RSAOAEPKeyExchangeDeformatter class with the specified key. |
| Name | Description | |
|---|---|---|
![]() | Parameters | Gets the parameters for the Optimal Asymmetric Encryption Padding (OAEP) key exchange. (Overrides AsymmetricKeyExchangeDeformatter.Parameters.) |
| Name | Description | |
|---|---|---|
![]() | DecryptKeyExchange | Extracts secret information from the encrypted key exchange data. (Overrides AsymmetricKeyExchangeDeformatter.DecryptKeyExchange(Byte[]).) |
![]() | 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 a hash function for a particular type. (Inherited from Object.) |
![]() | GetType | Gets the Type of the current instance. (Inherited from Object.) |
![]() | MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
![]() | SetKey | Sets the private key to use for decrypting the secret information. (Overrides AsymmetricKeyExchangeDeformatter.SetKey(AsymmetricAlgorithm).) |
![]() | ToString | Returns a string that represents the current object. (Inherited from Object.) |
Key exchange allows a sender to create secret information, for example, 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 RSAOAEPKeyExchangeFormatter to create the key exchange message with the RSA algorithm.
Caution |
|---|
It is highly recommended that you 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 RSAOAEPKeyExchangeDeformatter class to recreate an exchange key to be used to decrypt a message.
using System; using System.IO; using System.Security.Cryptography; using System.Text; class Alice { public static void Main(string[] args) { using (Bob bob = new Bob()) { using (RSACryptoServiceProvider rsaKey = new RSACryptoServiceProvider()) { // Get Bob's public key rsaKey.ImportCspBlob(bob.key); byte[] encryptedSessionKey = null; byte[] encryptedMessage = null; byte[] iv = null; Send(rsaKey, "Secret message", out iv, out encryptedSessionKey, out encryptedMessage); bob.Receive(iv, encryptedSessionKey, encryptedMessage); } } } private static void Send(RSA key, string secretMessage, out byte[] iv, out byte[] encryptedSessionKey, out byte[] encryptedMessage) { using (Aes aes = new AesCryptoServiceProvider()) { iv = aes.IV; // Encrypt the session key RSAOAEPKeyExchangeFormatter keyFormatter = new RSAOAEPKeyExchangeFormatter(key); encryptedSessionKey = keyFormatter.CreateKeyExchange(aes.Key, typeof(Aes)); // Encrypt the message using (MemoryStream ciphertext = new MemoryStream()) using (CryptoStream cs = new CryptoStream(ciphertext, aes.CreateEncryptor(), CryptoStreamMode.Write)) { byte[] plaintextMessage = Encoding.UTF8.GetBytes(secretMessage); cs.Write(plaintextMessage, 0, plaintextMessage.Length); cs.Close(); encryptedMessage = ciphertext.ToArray(); } } } } public class Bob : IDisposable { public byte[] key; private RSACryptoServiceProvider rsaKey = new RSACryptoServiceProvider(); public Bob() { key = rsaKey.ExportCspBlob(false); } public void Receive(byte[] iv, byte[] encryptedSessionKey, byte[] encryptedMessage) { using (Aes aes = new AesCryptoServiceProvider()) { aes.IV = iv; // Decrypt the session key RSAOAEPKeyExchangeDeformatter keyDeformatter = new RSAOAEPKeyExchangeDeformatter(rsaKey); aes.Key = keyDeformatter.DecryptKeyExchange(encryptedSessionKey); // Decrypt the message using (MemoryStream plaintext = new MemoryStream()) using (CryptoStream cs = new CryptoStream(plaintext, aes.CreateDecryptor(), CryptoStreamMode.Write)) { cs.Write(encryptedMessage, 0, encryptedMessage.Length); cs.Close(); string message = Encoding.UTF8.GetString(plaintext.ToArray()); Console.WriteLine(message); } } } public void Dispose() { rsaKey.Dispose(); } }
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.



Caution