在.NET中是否支持OFB cipherMode？

Question

我正在使用AESCryptoServiceProvider類。我試圖測試不同的CipherMode值。

當使用OFB模式時，我收到一個異常：指定了無效的算法。

在文檔的方式記載：

AESCryptoServiceProvider類 http://msdn.microsoft.com/es-es/library/system.security.cryptography.aescryptoserviceprovider.aspx

CipherMode http://msdn.microsoft.com/es-es/library/system.security.cryptography.ciphermode.aspx

我也看過這個類似的帖子，也未找到答案：

Does .NET support of AES OFB

我的代碼：

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Text; 

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

namespace V_ModosDeEncadenamiento 
{ 
    class Program 
    { 
     static void Main(string[] args) 
     { 
      //Clave de 128 
      byte[] claveAES128Bits = { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 
             0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F }; 


      //Vector de inicialización 
      byte[] vectorInicializacion = { 0xA0, 0xA1, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7, 
              0xA8, 0xA9, 0xAA, 0xAB, 0xAC, 0xAD, 0xAE, 0xAF }; 

      //Texto plano de prueba para codificar. Bloque de 16 bytes todos iguales 
      byte[] textoPlanoBloques16BytesIguales = 
             {0xB0, 0xB1, 0xB2, 0xB3, 0xB4, 0xB5, 0xB6, 0xB7, 
             0xB8, 0xB9, 0xBA, 0xBB, 0xBC, 0xBD, 0xBE, 0xBF, 
             0xB0, 0xB1, 0xB2, 0xB3, 0xB4, 0xB5, 0xB6, 0xB7, 
             0xB8, 0xB9, 0xBA, 0xBB, 0xBC, 0xBD, 0xBE, 0xBF, 
             0xB0, 0xB1, 0xB2, 0xB3, 0xB4, 0xB5, 0xB6, 0xB7, 
             0xB8, 0xB9, 0xBA, 0xBB, 0xBC, 0xBD, 0xBE, 0xBF}; 


      //Nombre del fichero en disco con texto cifrado 
      String nombreFicheroECB = "zz_TextoCifradoECB.bin"; 
      String nombreFicheroCBC = "zz_TextoCifradoCBC.bin"; 
      String nombreFicheroCFB = "zz_TextoCifradoCFB.bin"; 
      String nombreFicheroOFB = "zz_TextoCifradoOFB.bin"; 

      //Array con el texto descifrado 
      byte[] textoDescifrado = new byte[textoPlanoBloques16BytesIguales.Length]; 

      AesCryptoServiceProvider aesCrypto = new AesCryptoServiceProvider(); 
      FileStream fileWrite; 
      FileStream fileRead; 
      ICryptoTransform encryptor; 
      ICryptoTransform decryptor; 
      CryptoStream stream; 
      CryptoStream streamOut; 



      //Establecer valores 
      aesCrypto.KeySize = 128; 
      aesCrypto.Key = claveAES128Bits; 
      aesCrypto.IV = vectorInicializacion; 
      aesCrypto.Padding = PaddingMode.PKCS7; 

    aesCrypto.Mode = CipherMode.OFB; 
    fileWrite = new FileStream(nombreFicheroOFB, FileMode.Create, FileAccess.Write, FileShare.None); 
    encryptor = aesCrypto.CreateEncryptor(); 
    stream = new CryptoStream(fileWrite, encryptor, CryptoStreamMode.Write); 

    // THE EXCEPTION HAPPENS HERE ************************************************** 
    //****************************************************************************** 
    stream.Write(textoPlanoBloques16BytesIguales, 0, textoPlanoBloques16BytesIguales.Length); 
    stream.Flush(); 
    stream.Close(); 
    stream.Dispose(); 
    fileWrite.Close(); 

    fileRead = new FileStream(nombreFicheroOFB, FileMode.Open, FileAccess.Read, FileShare.None); 
    decryptor = aesCrypto.CreateDecryptor(); 
    streamOut = new CryptoStream(fileRead, decryptor, CryptoStreamMode.Read); 
    streamOut.Read(textoDescifrado, 0, textoDescifrado.Length); 
    streamOut.Flush(); 
    streamOut.Close(); 
    streamOut.Dispose(); 
    fileRead.Close(); 

    //Mostrar datos descifrados 
    Console.WriteLine(); 
    Console.WriteLine(); 
    Console.WriteLine("Cifrado modo EFB."); 
    Console.WriteLine("Datos descifrados:"); 
    for (int i = 0; i <= textoDescifrado.Length - 1; i++) 
    { 
     if (((i % 8) == 0) && (i != 0)) Console.WriteLine(); //8 bytes en cada linea 
     Console.Write(" {0:X2}", textoDescifrado[i]); 
    } 

Answer 1

檢查這篇文章：http://social.msdn.microsoft.com/Forums/is/netfxbcl/thread/891955cd-3125-487c-9746-9fd07f24b12f

RijndaelManaged的不此刻的支持OFB模式。 您可以自己編寫（幾乎很容易）OFB模式，在ECB模式之上，或使用端密碼術庫，如BouncyCastle，SecureBlackbox，其他任何其他。