private void Worker_DoWorkEncryption(object sender, DoWorkEventArgs e)
{
var worker = sender as BackgroundWorker;
worker.ReportProgress(0);
eo = Encryption.GenerateEncodedFile(inputFilePath, outputFilePath,
Globals.blockSize, cipherMode, fileExtension, recipents, worker);
}
public static EncryptionObject GenerateEncodedFile(string inputFilePath,
string outputFilePath, int blockSize, string cipherModeString,
string fileExtension, List <User> recipents,
BackgroundWorker worker)
{
int keySizeBits = 128;
//generate session key
byte[] sessionKey = EncryptionHelper.GenerateSessionKey(keySizeBits);
//get a dictionary with recipent emails and their encrypted session keys
Dictionary <string, string> recipentsKeysDict = Encryption.GetRecipentsEncryptedSessionKeys(sessionKey, recipents);
//initialization vector is set in AesEncryptFromFile and then put into header
byte[] IV = null;
string tempEncodedFile = "tempEncoded.xml";
CipherMode cipherMode = EncryptionHelper.CipherModeFromString(cipherModeString);
//encrypting input file and saving it in destined out file
using (Aes myAes = Aes.Create())
{
EncryptionHelper.AesEncryptFromFile(inputFilePath, tempEncodedFile, sessionKey, cipherMode, blockSize, out IV, worker);
//EncryptionHelper.AesEncryptFromFile(inputFilePath, tempEncodedFile, myAes.Key, myAes.Mode, myAes.BlockSize, out IV, worker);
//Encryption.DecryptToFile(pathToOutFile, decodedFileName, myAes.Key, myAes.Mode, myAes.BlockSize, IV);
}
string ivString = Convert.ToBase64String(IV);
string tempFileWithHeader = "tempHeader.xml";
XmlHelpers.GenerateXMLHeader(tempFileWithHeader, Globals.Algorithm,
keySizeBits.ToString(), blockSize.ToString(), cipherModeString, ivString, recipentsKeysDict, fileExtension);
//todo now only encoded text in file (no header)
MergeHeaderAndEncodedContentIntoOutputFile(outputFilePath, tempFileWithHeader, tempEncodedFile);
//todo temp
EncryptionObject eo = new EncryptionObject();
eo.blockSize = blockSize;
eo.ivString = ivString;
recipentsKeysDict.TryGetValue(recipents.First().Email, out string encSessionKey);
Console.WriteLine("enc session key " + encSessionKey);
eo.encryptedSessionKey = encSessionKey;
return(eo);
}
public static void DecryptFile(EncryptionObject eo, string filePath, string decodedFileName, User selectedUser)
{
Console.WriteLine("decrypting");
//todo temp
/*string tempEncodedFilePath = "tempEncodedContents";
* XmlHelpers.RetrieveXmlHeaderFromFile(filePath, out string xmlHeaderString, tempEncodedFilePath);
*
* XmlHelpers.ReadDataFromXMLHeader(xmlHeaderString,
* out string algorithm, out string keySize,
* out string blockSize, out string cipherMode,
* out string iv, out Dictionary<string, string> recipents,
* out string fileExtension);
*
*/
//recipents are kept in a dictionary as
//<recipentEmail, encryptedUserSessionKey> pairs
//to decrypt the file we need a session key
//we need to find selectedUser- the user that current user of the app claims to be-
//get their encryptedUserSessionKey
//and decrypt the key using user's private key
//todo maybe set to some noise, so that if foreach doesn't find anything, the decoding will work and produce noise-file
//todo temp
/*string encryptedSessionKeyString ="aaaa";
* foreach(KeyValuePair<string, string> emailKey in recipents)
* {
* if (emailKey.Key.Equals(selectedUser.Email))
* {
* encryptedSessionKeyString = emailKey.Value;
* break;
* }
* }
*
* //decrypt session key using user's private key
* string userPrivateKeyString = UsersManagement.GetUserPrivateKeyFromFile(selectedUser.Email);
*
* byte[] decryptedSessionKeyByte = EncryptionHelper.DecryptSessionKeyFromString(encryptedSessionKeyString, userPrivateKeyString);
*/
//todo temp to remove
string userPrivateKeyString = UsersManagement.GetUserPrivateKeyFromFile(selectedUser.Email);
byte[] decryptedSessionKeyByte = EncryptionHelper.DecryptSessionKeyFromString(eo.encryptedSessionKey, userPrivateKeyString);
Console.WriteLine("private key of " + selectedUser.Email + " is " + userPrivateKeyString);
CipherMode mode = CipherMode.CBC;
EncryptionHelper.AesDecryptToFile(filePath,
decodedFileName + ".txt",
decryptedSessionKeyByte, mode, eo.blockSize,
Convert.FromBase64String(eo.ivString));
//set cipher mode
//todo uncomment
/*CipherMode mode = CipherMode.CBC;
*
* switch (cipherMode)
* {
* case Globals.modeCBC:
* mode = CipherMode.CBC;
* break;
* case Globals.modeCFB:
* mode = CipherMode.CFB;
* break;
* case Globals.modeECB:
* mode = CipherMode.ECB;
* break;
* case Globals.modeOFB:
* mode = CipherMode.OFB;
* break;
*
* }
*
* EncryptionHelper.AesDecryptToFile(tempEncodedFilePath,
* decodedFileName + fileExtension,
* decryptedSessionKeyByte, mode, Int32.Parse(keySize), //not key size, should be block size!
* Convert.FromBase64String(iv));
*/
}
