c# - encriptar - Encriptación AES en archivos grandes

encriptar cookies c#

Question

Necesito cifrar y descifrar un archivo grande (~ 1GB). Intenté usar este ejemplo: http://www.codeproject.com/Articles/769741/Csharp-AES-bits-Encryption-Library-with-Salt Pero mi problema es que el archivo es muy grande, me sale la excepción de OutOfMemory . Así que necesito reemplazar la secuencia de la memoria con la secuencia de archivos, simplemente no estoy seguro de cómo hacerlo ...

(Agregando mi código :)

private static void AES_Encrypt(string srcFile, string encryptedFile, byte[] passwordBytes)
{
// Set your salt here, change it to meet your flavor:
// The salt bytes must be at least 8 bytes.
byte[] saltBytes = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8};
FileStream fsInput = new FileStream(srcFile,
FileMode.Open,
FileAccess.Read);
FileStream fsEncrypted = new FileStream(encryptedFile,
FileMode.Create,
FileAccess.Write);
using (RijndaelManaged AES = new RijndaelManaged())
{
AES.KeySize = 256;
AES.BlockSize = 128;
var key = new Rfc2898DeriveBytes(passwordBytes, saltBytes, 1000);
AES.Key = key.GetBytes(AES.KeySize / 8);
AES.IV = key.GetBytes(AES.BlockSize / 8);
AES.Mode = CipherMode.CBC;
using (var cs = new CryptoStream(fsEncrypted, AES.CreateEncryptor(), CryptoStreamMode.Write))
{
byte[] bytearrayinput = new byte[fsInput.Length - 1];
fsInput.Read(bytearrayinput, 0, bytearrayinput.Length);
cs.Write(bytearrayinput, 0, bytearrayinput.Length);
cs.Close();
fsInput.Flush();
fsInput.Close();
fsEncrypted.Close();
}
}
}
public static void AES_Decrypt(string encryptedFile, string decryptedFile, byte[] passwordBytes)
{
byte[] decryptedBytes = null;
// Set your salt here, change it to meet your flavor:
// The salt bytes must be at least 8 bytes.
byte[] saltBytes = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8};
FileStream fsread = new FileStream(encryptedFile,
FileMode.Open,
FileAccess.Read);
using (RijndaelManaged AES = new RijndaelManaged())
{
AES.KeySize = 256;
AES.BlockSize = 128;
var key = new Rfc2898DeriveBytes(passwordBytes, saltBytes, 1000);
AES.Key = key.GetBytes(AES.KeySize / 8);
AES.IV = key.GetBytes(AES.BlockSize / 8);
AES.Mode = CipherMode.CBC;
FileStream fsDecrypted = new FileStream(decryptedFile,
FileMode.Create,
FileAccess.Write);
using (var cs = new CryptoStream(fsDecrypted, AES.CreateDecryptor(), CryptoStreamMode.Write))
{
byte[] bytearrayinput = new byte[fsread.Length - 1];
fsread.Read(bytearrayinput, 0, bytearrayinput.Length);
cs.Write(bytearrayinput, 0, bytearrayinput.Length);
cs.Close();
fsread.Close();
fsDecrypted.Close();
}
}
}

Answer 1

Como está leyendo un archivo y escribiendo en un archivo, simplemente reemplace las secuencias de memoria por IOStream o FileStream.

Tendrá que refactorizar los procedimientos un poco para que no esperen / devuelvan matrices de bytes.

Answer 2

Eventualmente, este es el código que funcionó para mí:

 private static void AES_Encrypt(string inputFile, string outputFile, byte[] passwordBytes)
{
byte[] saltBytes = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8};
string cryptFile = outputFile;
FileStream fsCrypt = new FileStream(cryptFile, FileMode.Create);
RijndaelManaged AES = new RijndaelManaged();
AES.KeySize = 256;
AES.BlockSize = 128;
var key = new Rfc2898DeriveBytes(passwordBytes, saltBytes, 1000);
AES.Key = key.GetBytes(AES.KeySize / 8);
AES.IV = key.GetBytes(AES.BlockSize / 8);
AES.Padding = PaddingMode.Zeros;
AES.Mode = CipherMode.CBC;
CryptoStream cs = new CryptoStream(fsCrypt,
AES.CreateEncryptor(),
CryptoStreamMode.Write);
FileStream fsIn = new FileStream(inputFile, FileMode.Open);
int data;
while ((data = fsIn.ReadByte()) != -1)
cs.WriteByte((byte)data);
fsIn.Close();
cs.Close();
fsCrypt.Close();
}
private static void AES_Decrypt(string inputFile, string outputFile, byte[] passwordBytes)
{
byte[] saltBytes = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8};
FileStream fsCrypt = new FileStream(inputFile, FileMode.Open);
RijndaelManaged AES = new RijndaelManaged();
AES.KeySize = 256;
AES.BlockSize = 128;
var key = new Rfc2898DeriveBytes(passwordBytes, saltBytes, 1000);
AES.Key = key.GetBytes(AES.KeySize / 8);
AES.IV = key.GetBytes(AES.BlockSize / 8);
AES.Padding = PaddingMode.Zeros;
AES.Mode = CipherMode.CBC;
CryptoStream cs = new CryptoStream(fsCrypt,
AES.CreateDecryptor(),
CryptoStreamMode.Read);
FileStream fsOut = new FileStream(outputFile, FileMode.Create);
int data;
while ((data = cs.ReadByte()) != -1)
fsOut.WriteByte((byte)data);
fsOut.Close();
cs.Close();
fsCrypt.Close();
}
}

Answer 3

Así que creé una versión bastante rápida y de bajo consumo de memoria:
Utilizo un "buffer temporal" y también "uso una sal aleatoria y lo almaceno con el texto cifrado".
Para encriptar:

private void AES_Encrypt(string inputFile, string password)
{
//http://.com/questions/27645527/aes-encryption-on-large-files
//generate random salt
byte[] salt = GenerateRandomSalt();
//create output file name
FileStream fsCrypt = new FileStream(inputFile + ".aes", FileMode.Create);
//convert password string to byte arrray
byte[] passwordBytes = System.Text.Encoding.UTF8.GetBytes(password);
//Set Rijndael symmetric encryption algorithm
RijndaelManaged AES = new RijndaelManaged();
AES.KeySize = 256;
AES.BlockSize = 128;
AES.Padding = PaddingMode.PKCS7;
//http://.com/questions/2659214/why-do-i-need-to-use-the-rfc2898derivebytes-class-in-net-instead-of-directly
//"What it does is repeatedly hash the user password along with the salt." High iteration counts.
var key = new Rfc2898DeriveBytes(passwordBytes, salt, 50000);
AES.Key = key.GetBytes(AES.KeySize / 8);
AES.IV = key.GetBytes(AES.BlockSize / 8);
//Cipher modes: http://security.stackexchange.com/questions/52665/which-is-the-best-cipher-mode-and-padding-mode-for-aes-encryption
AES.Mode = CipherMode.CFB;
//write salt to the begining of the output file, so in this case can be random every time
fsCrypt.Write(salt, 0, salt.Length);
CryptoStream cs = new CryptoStream(fsCrypt, AES.CreateEncryptor(), CryptoStreamMode.Write);
FileStream fsIn = new FileStream(inputFile, FileMode.Open);
//create a buffer (1mb) so only this amount will allocate in the memory and not the whole file
byte[] buffer = new byte[1048576];
int read;
try
{
while ((read = fsIn.Read(buffer, 0, buffer.Length)) > 0)
{
Application.DoEvents(); // -> for responsive GUI, using Task will be better!
cs.Write(buffer, 0, read);
}
//close up
fsIn.Close();
}
catch (Exception ex)
{
Debug.WriteLine("Error: " + ex.Message);
}
finally
{
cs.Close();
fsCrypt.Close();
}
}

Para descifrar:

private void AES_Decrypt(string inputFile, string password)
{
//todo:
// - create error message on wrong password
// - on cancel: close and delete file
// - on wrong password: close and delete file!
// - create a better filen name
// - could be check md5 hash on the files but it make this slow
byte[] passwordBytes = System.Text.Encoding.UTF8.GetBytes(password);
byte[] salt = new byte[32];
FileStream fsCrypt = new FileStream(inputFile, FileMode.Open);
fsCrypt.Read(salt, 0, salt.Length);
RijndaelManaged AES = new RijndaelManaged();
AES.KeySize = 256;
AES.BlockSize = 128;
var key = new Rfc2898DeriveBytes(passwordBytes, salt, 50000);
AES.Key = key.GetBytes(AES.KeySize / 8);
AES.IV = key.GetBytes(AES.BlockSize / 8);
AES.Padding = PaddingMode.PKCS7;
AES.Mode = CipherMode.CFB;
CryptoStream cs = new CryptoStream(fsCrypt, AES.CreateDecryptor(), CryptoStreamMode.Read);
FileStream fsOut = new FileStream(inputFile + ".decrypted", FileMode.Create);
int read;
byte[] buffer = new byte[1048576];
try
{
while ((read = cs.Read(buffer, 0, buffer.Length)) > 0)
{
Application.DoEvents();
fsOut.Write(buffer, 0, read);
}
}
catch (System.Security.Cryptography.CryptographicException ex_CryptographicException)
{
Debug.WriteLine("CryptographicException error: " + ex_CryptographicException.Message);
}
catch (Exception ex)
{
Debug.WriteLine("Error: " + ex.Message);
}
try
{
cs.Close();
}
catch (Exception ex)
{
Debug.WriteLine("Error by closing CryptoStream: " + ex.Message);
}
finally
{
fsOut.Close();
fsCrypt.Close();
}
}

Para generar sal aleatoria:

 public static byte[] GenerateRandomSalt()
{
//Source: http://www.dotnetperls.com/rngcryptoserviceprovider
byte[] data = new byte[32];
using (RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider())
{
// Ten iterations.
for (int i = 0; i < 10; i++)
{
// Fill buffer.
rng.GetBytes(data);
}
}
return data;
}