RSAPKCS1KeyExchangeDeformatter.DecryptKeyExchange(Byte[]) Method

Reference

Definition

Namespace:: System.Security.Cryptography

Assembly:: System.Security.Cryptography.Algorithms.dll

Assembly:: System.Security.Cryptography.dll

Assembly:: mscorlib.dll

Assembly:: netstandard.dll

Source:: RSAPKCS1KeyExchangeDeformatter.cs

Source:: RSAPKCS1KeyExchangeDeformatter.cs

Source:: RSAPKCS1KeyExchangeDeformatter.cs

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

Extracts secret information from the encrypted key exchange data.

public:
 override cli::array <System::Byte> ^ DecryptKeyExchange(cli::array <System::Byte> ^ rgbIn);

public override byte[] DecryptKeyExchange (byte[] rgbIn);

override this.DecryptKeyExchange : byte[] -> byte[]

Public Overrides Function DecryptKeyExchange (rgbIn As Byte()) As Byte()

Parameters

rgbIn: Byte[]

The key exchange data within which the secret information is hidden.

Returns

Byte[]

The secret information derived from the key exchange data.

Exceptions

CryptographicUnexpectedOperationException

The key is missing.

Examples

The following example shows how to use the DecryptKeyExchange method to recreate an exchange key from a message sender. This code example is part of a larger example provided for the RSAPKCS1KeyExchangeDeformatter class.

public void Receive(byte[] iv, byte[] encryptedSessionKey, byte[] encryptedMessage)
{

    using (Aes aes = new AesCryptoServiceProvider())
    {
        aes.IV = iv;

        // Decrypt the session key
        RSAPKCS1KeyExchangeDeformatter keyDeformatter = new RSAPKCS1KeyExchangeDeformatter(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 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

Remarks

You must specify a key before calling this method.

Applies to

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