private static void _DecryptPreprocess(string inputFile)
{
string outputFile = inputFile + ".tmp";
int numberOfBytes = 16;
byte[] bytes = new byte[numberOfBytes];
//get GUID from file
using (var fs = new FileStream(inputFile, FileMode.Open, FileAccess.Read))
{
fs.Read(bytes, 0, bytes.Length);
}
// var buffer2 = File.ReadAllBytes(inputFile);
Guid guid = new Guid(bytes);
string GUID = guid.ToString();
//create new file without GUID
char[] delimiterChars = { '.' };
string[] newFile = outputFile.Split(delimiterChars);
string newFileFullPathName = String.Join(".", newFile.Take(newFile.Length - 2));
using (var fs = new FileStream(inputFile, FileMode.Open, FileAccess.Read))
{
byte[] fullfile = new byte[fs.Length];
int toRead = (int)fs.Length - 1, bytesRead;
fs.Seek(16, SeekOrigin.Begin);
while (toRead > 0 && (bytesRead = fs.Read(fullfile, 0, toRead)) > 0)
{
toRead -= bytesRead;
numberOfBytes += bytesRead;
}
using (var newFS = new FileStream(outputFile, FileMode.Create, FileAccess.Write))
{
newFS.Write(fullfile, 0, fullfile.Length);
}
}
//get IV and key from SQLite DB
SecureboxKey el = DatabaseManagement.GetSecureboxKey(GUID);
if (el != null &&
el.IV != null &&
el.IV.Length > 0)
{
Securebox._DecryptFile(outputFile, newFileFullPathName, el);
}
Securebox.DeleteCurrentFile(outputFile);
}
private static void _EncryptFile(string inputFile, string outputFile, Guid GUID)
{
try
{
using (AesCryptoServiceProvider aes = new AesCryptoServiceProvider())
{
/* This is for demostrating purposes only.
* Ideally you will want the IV key to be different from your key and you should always generate a new one for each encryption in other to achieve maximum security*/
byte[] IV = GUID.ToByteArray();
byte[] key = GUID.ToByteArray();
DatabaseManagement.InsertKey(GUID.ToString(), IV, key);
using (FileStream fsCrypt = new FileStream(outputFile, FileMode.Create))
{
using (ICryptoTransform encryptor = aes.CreateEncryptor(key, IV))
{
using (CryptoStream cs = new CryptoStream(fsCrypt, encryptor, CryptoStreamMode.Write))
{
using (FileStream fsIn = new FileStream(inputFile, FileMode.Open))
{
int data;
while ((data = fsIn.ReadByte()) != -1)
{
cs.WriteByte((byte)data);
}
}
}
}
}
}
}
catch (Exception ex)
{
Debug.WriteLine(ex.Message);
}
Securebox.DeleteCurrentFile(inputFile);
}
private static Boolean _PostProcessEncryptFile(string inputFile, string outputFile, Guid GUID)
{
Boolean isCancelEncryptionProcess = false;
if (File.Exists(outputFile))
{
DialogResult dialogResult = System.Windows.Forms.MessageBox.Show("Would you like to overwrite an existing file?\nSelecting 'No' will append the current file name with a - and a numeral for the current file.\nSelecting 'Cancel' will skip all remaining files as well as this file", "Overwrite confirmation", MessageBoxButtons.YesNoCancel);
if (dialogResult == DialogResult.Yes)
{
Securebox.DeleteCurrentFile(outputFile);
Securebox._PostProcessEncryptFileMethod(inputFile, outputFile, GUID);
}
isCancelEncryptionProcess = dialogResult == DialogResult.Cancel;
}
else
{
Securebox._PostProcessEncryptFileMethod(inputFile, outputFile, GUID);
}
Securebox.DeleteCurrentFile(inputFile);
return(isCancelEncryptionProcess);
}
