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What is the problem of increasing the time encryption of my stream cipher algorithm?

I have my own stream cipher algorithm, and I made a comparison between it and AES performance. I tested it on several files with different sizes(to 500KB). Its encryption/decryption time is less than AES for files about 500KB. but with files more than 500KB, its encryption time is more than AES but still its decryption time is the least one.
public static byte[] AES_Encrypt(byte[] bytesToBeEncrypted, byte[] passwordBytes)
{
byte[] encryptedBytes = null;
byte[] saltBytes = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };
using (MemoryStream ms = new MemoryStream())
{
using (RijndaelManaged AES = new RijndaelManaged())
{
AES.KeySize = 128;
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.CFB;
using (var cs = new CryptoStream(ms,
AES.CreateEncryptor(), CryptoStreamMode.Write))
{
cs.Write(bytesToBeEncrypted, 0,
bytesToBeEncrypted.Length);
cs.Close();
}
encryptedBytes = ms.ToArray();
}
ms.Close();
}
return encryptedBytes;
}
public static byte[] AES_Decrypt(byte[] bytesToBeDecrypted, byte[] passwordBytes)
{
byte[] decryptedBytes = null;
byte[] saltBytes = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };
using (MemoryStream ms = new MemoryStream())
{
using (RijndaelManaged AES = new RijndaelManaged())
{
AES.KeySize = 128;
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.CFB;
using (var cs = new CryptoStream(ms,
AES.CreateDecryptor(), CryptoStreamMode.Write))
{
cs.Write(bytesToBeDecrypted, 0,
bytesToBeDecrypted.Length);
cs.Close();
}
decryptedBytes = ms.ToArray();
}
}
return decryptedBytes;
}

How to encrypt files in a folder

I'm making a program to encrypt all files in a folder to not encrypt files 1 by 1.
So, here is my code for the AES 256 encryption
public class CoreEncryption
{
public static byte[] AES_Encrypt(byte[] bytesToBeEncrypted, byte[] passwordBytes)
{
byte[] encryptedBytes = 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 };
using (MemoryStream ms = new MemoryStream())
{
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(ms, AES.CreateEncryptor(), CryptoStreamMode.Write))
{
cs.Write(bytesToBeEncrypted, 0, bytesToBeEncrypted.Length);
cs.Close();
}
encryptedBytes = ms.ToArray();
}
}
return encryptedBytes;
}
}
public class CoreDecryption
{
public static byte[] AES_Decrypt(byte[] bytesToBeDecrypted, 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 };
using (MemoryStream ms = new MemoryStream())
{
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(ms, AES.CreateDecryptor(), CryptoStreamMode.Write))
{
cs.Write(bytesToBeDecrypted, 0, bytesToBeDecrypted.Length);
cs.Close();
}
decryptedBytes = ms.ToArray();
}
}
return decryptedBytes;
}
}
And this to start encrypting and decrypting files
public class EncryptionFile
{
public void EncryptFile(string file, string password)
{
byte[] bytesToBeEncrypted = File.ReadAllBytes(file);
byte[] passwordBytes = Encoding.UTF8.GetBytes(password);
// Hash the password with SHA256
passwordBytes = SHA256.Create().ComputeHash(passwordBytes);
byte[] bytesEncrypted = CoreEncryption.AES_Encrypt(bytesToBeEncrypted, passwordBytes);
string fileEncrypted = file;
File.WriteAllBytes(fileEncrypted, bytesEncrypted);
}
}
public class DecryptionFile
{
public void DecryptFile(string fileEncrypted, string password)
{
byte[] bytesToBeDecrypted = File.ReadAllBytes(fileEncrypted);
byte[] passwordBytes = Encoding.UTF8.GetBytes(password);
passwordBytes = SHA256.Create().ComputeHash(passwordBytes);
byte[] bytesDecrypted = CoreDecryption.AES_Decrypt(bytesToBeDecrypted, passwordBytes);
string file = fileEncrypted;
File.WriteAllBytes(file, bytesDecrypted);
}
}
So now, I want to enter a folder path, and that my encryption process crypt every files in that chosen folder. How can I do that ?

Um....
Just like this?
It works fine on (Windows10 pro x64 / Visual Studio 2017).
Good luck.
//! ----------------------------------------------------------------
static void Test1()
{
string[] files = Directory.GetFiles(#"D:\_test", "*", SearchOption.AllDirectories);
EncryptionFile enc = new EncryptionFile();
//DecryptionFile dec = new DecryptionFile();
string password = "abcd";
for (int i=0; i<files.Length; i++)
{
Console.WriteLine(files[i]);
enc.EncryptFile(files[i], password);
//dec.DecryptFile(files[i], password);
}
}

RijndaelManaged - encrypt in C# and decrypt in Java

I have c sharp code snippet for encryption which uses .Key file for key and my requirement is to decrypt the encrypted text using same key in android, having problem
public static byte[] AES_Encrypt(byte[] bytesToBeEncrypted, byte[] passwordBytes) {
byte[] encryptedBytes = 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 };
using (MemoryStream ms = new MemoryStream())
{
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(ms, AES.CreateEncryptor(), CryptoStreamMode.Write))
{
cs.Write(bytesToBeEncrypted, 0, bytesToBeEncrypted.Length);
cs.Close();
}
encryptedBytes = ms.ToArray();
}
}
return encryptedBytes;
}

If you want to decrypt some data with AES you can use this method:
private static byte[] decrypt(byte[] raw, byte[] encrypted) throws Exception {
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.DECRYPT_MODE, skeySpec);
byte[] decrypted = cipher.doFinal(encrypted);
return decrypted;
}
for complete code look at : android encryption/decryption with AES

C# Encrypt data AES

Is there a way to encrypt data with AES? I'd love to use at least 128 Bits for the encryption Key.
I tried with AES default class provided by Microsoft but I can't do a lot... I can't set the Key Lenght.
Is there another Class that I can use?

Yes. You can use the code listed at http://www.codeproject.com/Articles/769741/Csharp-AES-bits-Encryption-Library-with-Salt
You Can Use RIJNDAEL:
First you need to include using System.Security.Cryptography;
public byte[] AES_Encrypt(byte[] bytesToBeEncrypted, byte[] passwordBytes)
{
byte[] encryptedBytes = 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 };
using (MemoryStream ms = new MemoryStream())
{
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(ms, AES.CreateEncryptor(), CryptoStreamMode.Write))
{
cs.Write(bytesToBeEncrypted, 0, bytesToBeEncrypted.Length);
cs.Close();
}
encryptedBytes = ms.ToArray();
}
}
return encryptedBytes;
}
public byte[] AES_Decrypt(byte[] bytesToBeDecrypted, 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 };
using (MemoryStream ms = new MemoryStream())
{
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(ms, AES.CreateDecryptor(), CryptoStreamMode.Write))
{
cs.Write(bytesToBeDecrypted, 0, bytesToBeDecrypted.Length);
cs.Close();
}
decryptedBytes = ms.ToArray();
}
}
return decryptedBytes;
}
public void EncryptFile(string filename, string outfilename, string psw)
{
string file = filename;
string password = psw;
byte[] bytesToBeEncrypted = File.ReadAllBytes(file); //read bytes to encrypt them
byte[] passwordBytes = Encoding.UTF8.GetBytes(password); //read with UTF8 encoding the password.
passwordBytes = SHA256.Create().ComputeHash(passwordBytes); //hash the psw
byte[] bytesEncrypted = AES_Encrypt(bytesToBeEncrypted, passwordBytes);
string fileEncrypted = outfilename;
File.WriteAllBytes(fileEncrypted, bytesEncrypted);
}
public void DecryptFile(string filename, string outfilename, string psw)
{
string fileEncrypted = filename;
string password = psw;
byte[] bytesToBeDecrypted = File.ReadAllBytes(fileEncrypted);
byte[] passwordBytes = Encoding.UTF8.GetBytes(password);
passwordBytes = SHA256.Create().ComputeHash(passwordBytes);
byte[] bytesDecrypted = AES_Decrypt(bytesToBeDecrypted, passwordBytes);
string file = outfilename;
File.WriteAllBytes(file, bytesDecrypted);
}

AES encryption on large files

I need to encrypt and decrypt large file (~1GB).
I tried using this example: http://www.codeproject.com/Articles/769741/Csharp-AES-bits-Encryption-Library-with-Salt
But my problem is since the file is very large, I'm getting outOfMemory exception.
So I need to replace the memory stream with file stream, I just not sure how to do it...
(Adding my code:)
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();
}
}
}

Eventually, this is the code that worked for me:
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();
}
}

So I created a fairly fast and low memory consumption version:
I use a "temporary buffer" and also "use a random salt and store it with the ciphertext".
To encrypt:
private void AES_Encrypt(string inputFile, string password)
{
//http://stackoverflow.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://stackoverflow.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();
}
}
To decrypt:
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();
}
}
To generate random salt:
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;
}

Since you are reading from a file and writing to a file just replace the memory streams by IOStream or FileStream.
You'll have to refactor the procedures a bit so they don't expect/return byte arrays.

For anyone still looking into this and don't want the output to a file but rather a stream
the key is to make sure to call cryptoStream.FlushFinalBlock(); otherwise the decrypt will miss the last few characters.
public MemoryStream FileEncrypt(string inputFilePath, byte[] passwordBytes)
{
var saltBytes = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };
var memoryStream = new MemoryStream();
var aes = new RijndaelManaged {KeySize = 256, 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;
var cryptoStream = new CryptoStream(memoryStream, aes.CreateEncryptor(), CryptoStreamMode.Write);
var fileStream = new FileStream(inputFilePath, FileMode.Open);
int data;
while ((data = fileStream.ReadByte()) != -1)
cryptoStream.WriteByte((byte)data);
cryptoStream.FlushFinalBlock();
return memoryStream;
}
public MemoryStream FileDecrypt(Stream encryptedFileStream, byte[] passwordBytes)
{
var saltBytes = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };
var AES = new RijndaelManaged {KeySize = 256, 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;
var cryptoStream = new CryptoStream(encryptedFileStream, AES.CreateDecryptor(), CryptoStreamMode.Read);
var memoryStream = new MemoryStream();
int data;
while ((data = cryptoStream.ReadByte()) != -1)
memoryStream.WriteByte((byte)data);
return memoryStream;
}