private static byte[] ReadAndSkip(byte[] data, out byte[] readBytes)
{
int length = BitConverter.ToInt32(data.Take(4).ToArray(), 0);
data = data.Skip(4).ToArray();
readBytes = data.Take(length).ToArray();
data = data.Skip(readBytes.Length).ToArray();
readBytes = AsymmetricEncDec.DecryptInformation(receiver, readBytes);
return(data);
}
public static bool Encrypt(string algorithm, string hashAlg, string filePath)
{
byte[] key = RandomKeyGenerator(SymetricEncDec.keyLenght[algorithm]);
//get data
byte[] dataForEncryption = ReadFile(filePath);
byte[] dataEncrypted = SymetricEncDec.Encrypt(dataForEncryption, algorithm, key);
//get hash
byte[] hash = HashAlg.Hash(dataForEncryption, hashAlg);
hash = AsymmetricEncDec.SignData(hash, sender, hashAlg);
WriteWithHeader(algorithm, hashAlg, key, hash.Length, dataEncrypted, hash, receiver.Folder + "\\" + sender.Username + new Random().Next(0, 100) + ".cs");
return(true);
}
public static string Decrypt(string filePath)
{
byte[] data;
byte[] symetricAlg;
byte[] key;
byte[] hash;
byte[] hashingAlg;
int hashLength;
using (BinaryReader reader = new BinaryReader(File.Open(filePath, FileMode.Open)))
{
try
{
data = reader.ReadBytes((int)(new System.IO.FileInfo(filePath).Length));
data = ReadAndSkip(data, out symetricAlg);
data = ReadAndSkip(data, out hashingAlg);
data = ReadAndSkip(data, out key);
}
catch (Exception)
{
MessageBox.Show("Decryption with your private key failed.");
return(null);
}
//get signed hash
hashLength = BitConverter.ToInt32(data.Take(4).ToArray(), 0);
data = data.Skip(4).ToArray();
hash = data.Take(hashLength).ToArray();
//get encrypted data
data = data.Skip(hashLength).ToArray();
}
byte[] dataDecrypted = SymetricEncDec.Decrypt(data, Encoding.UTF8.GetString(symetricAlg), key);
byte[] result = HashAlg.Hash(dataDecrypted, Encoding.UTF8.GetString(hashingAlg));
if (AsymmetricEncDec.VerifySignature(hash, sender, result, Encoding.UTF8.GetString(hashingAlg)) == false)
{
return(null);
}
string filePathOut = filePath.Remove(filePath.LastIndexOf('.')) + "Dec.cs";
WriteToFile(filePathOut, dataDecrypted);
return(filePathOut);
}
private static void WriteAndAdd(byte[] data, BinaryWriter writer)
{
byte[] tmp = AsymmetricEncDec.EncryptInformation(receiver, data);
writer.Write(tmp.Length);
WriteHeader(tmp, writer);
}
