c# - .NET 是否支持 OFB cipherMode？

Question

我正在使用 AESCryptoServiceProvider 类。我正在尝试测试不同的 CipherMode 值。

使用OFB模式时出现异常:指定的算法无效。

在文档中记录了模式:

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

密码模式 http://msdn.microsoft.com/es-es/library/system.security.cryptography.ciphermode.aspx

我也看过这个类似的帖子，但没有找到答案:

Does .NET support of AES OFB

我的代码:

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

查看这篇文章:http://social.msdn.microsoft.com/Forums/is/netfxbcl/thread/891955cd-3125-487c-9746-9fd07f24b12f

RijndaelManaged 目前不支持 OFB 模式。您可以(几乎轻松地)在 ECB 模式之上自己编写 OFB 模式代码，或者使用辅助加密库，例如 BouncyCaSTLe、SecureBlackbox 等。