Rfc2898DeriveBytes Classe

Definizione

public ref class Rfc2898DeriveBytes : System::Security::Cryptography::DeriveBytes

[System.Runtime.Versioning.UnsupportedOSPlatform("browser")]
public class Rfc2898DeriveBytes : System.Security.Cryptography.DeriveBytes

public class Rfc2898DeriveBytes : System.Security.Cryptography.DeriveBytes

[System.Runtime.InteropServices.ComVisible(true)]
public class Rfc2898DeriveBytes : System.Security.Cryptography.DeriveBytes

[<System.Runtime.Versioning.UnsupportedOSPlatform("browser")>]
type Rfc2898DeriveBytes = class
    inherit DeriveBytes

type Rfc2898DeriveBytes = class
    inherit DeriveBytes

[<System.Runtime.InteropServices.ComVisible(true)>]
type Rfc2898DeriveBytes = class
    inherit DeriveBytes

Public Class Rfc2898DeriveBytes
Inherits DeriveBytes

Ereditarietà

Object

DeriveBytes

Rfc2898DeriveBytes

Attributi

UnsupportedOSPlatformAttribute ComVisibleAttribute

Esempio

Nell'esempio di codice seguente viene usata la Rfc2898DeriveBytes classe per creare due chiavi identiche per la Aes classe. Crittografa e decrittografa alcuni dati usando le chiavi.

using namespace System;
using namespace System::IO;
using namespace System::Text;
using namespace System::Security::Cryptography;

// Generate a key k1 with password pwd1 and salt salt1.
// Generate a key k2 with password pwd1 and salt salt1.
// Encrypt data1 with key k1 using symmetric encryption, creating edata1.
// Decrypt edata1 with key k2 using symmetric decryption, creating data2.
// data2 should equal data1.

int main()
{
   array<String^>^passwordargs = Environment::GetCommandLineArgs();
   String^ usageText = "Usage: RFC2898 <password>\nYou must specify the password for encryption.\n";

   //If no file name is specified, write usage text.
   if ( passwordargs->Length == 1 )
   {
      Console::WriteLine( usageText );
   }
   else
   {
      String^ pwd1 = passwordargs[ 1 ];
      
      array<Byte>^salt1 = gcnew array<Byte>(8);
      RNGCryptoServiceProvider ^ rngCsp = gcnew RNGCryptoServiceProvider();
         rngCsp->GetBytes(salt1);
      //data1 can be a string or contents of a file.
      String^ data1 = "Some test data";

      //The default iteration count is 1000 so the two methods use the same iteration count.
      int myIterations = 1000;

      try
      {
         Rfc2898DeriveBytes ^ k1 = gcnew Rfc2898DeriveBytes( pwd1,salt1,myIterations );
         Rfc2898DeriveBytes ^ k2 = gcnew Rfc2898DeriveBytes( pwd1,salt1 );

         // Encrypt the data.
         Aes^ encAlg = Aes::Create();
         encAlg->Key = k1->GetBytes( 16 );
         MemoryStream^ encryptionStream = gcnew MemoryStream;
         CryptoStream^ encrypt = gcnew CryptoStream( encryptionStream,encAlg->CreateEncryptor(),CryptoStreamMode::Write );
         array<Byte>^utfD1 = (gcnew System::Text::UTF8Encoding( false ))->GetBytes( data1 );

         encrypt->Write( utfD1, 0, utfD1->Length );
         encrypt->FlushFinalBlock();
         encrypt->Close();
         array<Byte>^edata1 = encryptionStream->ToArray();
         k1->Reset();

         // Try to decrypt, thus showing it can be round-tripped.
         Aes^ decAlg = Aes::Create();
         decAlg->Key = k2->GetBytes( 16 );
         decAlg->IV = encAlg->IV;
         MemoryStream^ decryptionStreamBacking = gcnew MemoryStream;
         CryptoStream^ decrypt = gcnew CryptoStream( decryptionStreamBacking,decAlg->CreateDecryptor(),CryptoStreamMode::Write );

         decrypt->Write( edata1, 0, edata1->Length );
         decrypt->Flush();
         decrypt->Close();
         k2->Reset();

         String^ data2 = (gcnew UTF8Encoding( false ))->GetString( decryptionStreamBacking->ToArray() );
         if (  !data1->Equals( data2 ) )
         {
            Console::WriteLine( "Error: The two values are not equal." );
         }
         else
         {
            Console::WriteLine( "The two values are equal." );
            Console::WriteLine( "k1 iterations: {0}", k1->IterationCount );
            Console::WriteLine( "k2 iterations: {0}", k2->IterationCount );
         }
      }

      catch ( Exception^ e ) 
      {
         Console::WriteLine( "Error: ", e );
      }
   }
}

using System;
using System.IO;
using System.Text;
using System.Security.Cryptography;

public class rfc2898test
{
    // Generate a key k1 with password pwd1 and salt salt1.
    // Generate a key k2 with password pwd1 and salt salt1.
    // Encrypt data1 with key k1 using symmetric encryption, creating edata1.
    // Decrypt edata1 with key k2 using symmetric decryption, creating data2.
    // data2 should equal data1.

    private const string usageText = "Usage: RFC2898 <password>\nYou must specify the password for encryption.\n";
    public static void Main(string[] passwordargs)
    {
        //If no file name is specified, write usage text.
        if (passwordargs.Length == 0)
        {
            Console.WriteLine(usageText);
        }
        else
        {
            string pwd1 = passwordargs[0];
            // Create a byte array to hold the random value.
            byte[] salt1 = new byte[8];
            using (RNGCryptoServiceProvider rngCsp = new
RNGCryptoServiceProvider())
            {
                // Fill the array with a random value.
                rngCsp.GetBytes(salt1);
            }

            //data1 can be a string or contents of a file.
            string data1 = "Some test data";
            //The default iteration count is 1000 so the two methods use the same iteration count.
            int myIterations = 1000;
            try
            {
                Rfc2898DeriveBytes k1 = new Rfc2898DeriveBytes(pwd1, salt1,
myIterations);
                Rfc2898DeriveBytes k2 = new Rfc2898DeriveBytes(pwd1, salt1);
                // Encrypt the data.
                Aes encAlg = Aes.Create();
                encAlg.Key = k1.GetBytes(16);
                MemoryStream encryptionStream = new MemoryStream();
                CryptoStream encrypt = new CryptoStream(encryptionStream,
encAlg.CreateEncryptor(), CryptoStreamMode.Write);
                byte[] utfD1 = new System.Text.UTF8Encoding(false).GetBytes(
data1);

                encrypt.Write(utfD1, 0, utfD1.Length);
                encrypt.FlushFinalBlock();
                encrypt.Close();
                byte[] edata1 = encryptionStream.ToArray();
                k1.Reset();

                // Try to decrypt, thus showing it can be round-tripped.
                Aes decAlg = Aes.Create();
                decAlg.Key = k2.GetBytes(16);
                decAlg.IV = encAlg.IV;
                MemoryStream decryptionStreamBacking = new MemoryStream();
                CryptoStream decrypt = new CryptoStream(
decryptionStreamBacking, decAlg.CreateDecryptor(), CryptoStreamMode.Write);
                decrypt.Write(edata1, 0, edata1.Length);
                decrypt.Flush();
                decrypt.Close();
                k2.Reset();
                string data2 = new UTF8Encoding(false).GetString(
decryptionStreamBacking.ToArray());

                if (!data1.Equals(data2))
                {
                    Console.WriteLine("Error: The two values are not equal.");
                }
                else
                {
                    Console.WriteLine("The two values are equal.");
                    Console.WriteLine("k1 iterations: {0}", k1.IterationCount);
                    Console.WriteLine("k2 iterations: {0}", k2.IterationCount);
                }
            }
            catch (Exception e)
            {
                Console.WriteLine("Error: {0}", e);
            }
        }
    }
}

Imports System.IO
Imports System.Text
Imports System.Security.Cryptography



Public Class rfc2898test
    ' Generate a key k1 with password pwd1 and salt salt1.
    ' Generate a key k2 with password pwd1 and salt salt1.
    ' Encrypt data1 with key k1 using symmetric encryption, creating edata1.
    ' Decrypt edata1 with key k2 using symmetric decryption, creating data2.
    ' data2 should equal data1.
    Private Const usageText As String = "Usage: RFC2898 <password>" + vbLf + "You must specify the password for encryption." + vbLf

    Public Shared Sub Main(ByVal passwordargs() As String)
        'If no file name is specified, write usage text.
        If passwordargs.Length = 0 Then
            Console.WriteLine(usageText)
        Else
            Dim pwd1 As String = passwordargs(0)

            Dim salt1(8) As Byte
            Using rngCsp As New RNGCryptoServiceProvider()
                rngCsp.GetBytes(salt1)
            End Using
            'data1 can be a string or contents of a file.
            Dim data1 As String = "Some test data"
            'The default iteration count is 1000 so the two methods use the same iteration count.
            Dim myIterations As Integer = 1000
            Try
                Dim k1 As New Rfc2898DeriveBytes(pwd1, salt1, myIterations)
                Dim k2 As New Rfc2898DeriveBytes(pwd1, salt1)
                ' Encrypt the data.
                Dim encAlg As Aes = Aes.Create()
                encAlg.Key = k1.GetBytes(16)
                Dim encryptionStream As New MemoryStream()
                Dim encrypt As New CryptoStream(encryptionStream, encAlg.CreateEncryptor(), CryptoStreamMode.Write)
                Dim utfD1 As Byte() = New System.Text.UTF8Encoding(False).GetBytes(data1)
                encrypt.Write(utfD1, 0, utfD1.Length)
                encrypt.FlushFinalBlock()
                encrypt.Close()
                Dim edata1 As Byte() = encryptionStream.ToArray()
                k1.Reset()

                ' Try to decrypt, thus showing it can be round-tripped.
                Dim decAlg As Aes = Aes.Create()
                decAlg.Key = k2.GetBytes(16)
                decAlg.IV = encAlg.IV
                Dim decryptionStreamBacking As New MemoryStream()
                Dim decrypt As New CryptoStream(decryptionStreamBacking, decAlg.CreateDecryptor(), CryptoStreamMode.Write)
                decrypt.Write(edata1, 0, edata1.Length)
                decrypt.Flush()
                decrypt.Close()
                k2.Reset()
                Dim data2 As String = New UTF8Encoding(False).GetString(decryptionStreamBacking.ToArray())

                If Not data1.Equals(data2) Then
                    Console.WriteLine("Error: The two values are not equal.")
                Else
                    Console.WriteLine("The two values are equal.")
                    Console.WriteLine("k1 iterations: {0}", k1.IterationCount)
                    Console.WriteLine("k2 iterations: {0}", k2.IterationCount)
                End If
            Catch e As Exception
                Console.WriteLine("Error: ", e)
            End Try
        End If

    End Sub
End Class

Commenti

Rfc2898DeriveBytes accetta una password, un sale e un numero di iterazioni e quindi genera chiavi tramite chiamate al GetBytes metodo.

RFC 2898 include metodi per la creazione di una chiave e un vettore di inizializzazione (IV) da una password e un sale. È possibile usare PBKDF2, una funzione di derivazione della chiave basata su password, per derivare chiavi usando una funzione pseudo casuale che consente la generazione di chiavi di lunghezza virtualmente illimitata. La Rfc2898DeriveBytes classe può essere usata per produrre una chiave derivata da una chiave di base e da altri parametri. In una funzione di derivazione della chiave basata su password, la chiave di base è una password e gli altri parametri sono un valore salt e un numero di iterazioni.

Per altre informazioni su PBKDF2, vedere RFC 2898, denominato "PKCS #5: Password-Based specifica di crittografia versione 2.0". Per informazioni dettagliate, vedere la sezione 5.2, "PBKDF2".

Costruttori

Proprietà

Metodi

Si applica a

Vedi anche

• servizi crittografici