I'm trying to learn cyber security and this is the very first thing I've done on it. I'm using this MSDN document ( https://learn.microsoft.com/en-us/dotnet/api/system.security.cryptography.rfc2898derivebytes?redirectedfrom=MSDN&view=netcore-3.1 ) and it partly works. I assume it's encrypting it fine as when it comes to the decryption some of the original data is there but some is lost. The data that is being encrypted is a class that has been formatted into a JSON string( I don't think this is relevant as it's still a string being encrypted).
But once it's been encrypted and decrypted it turns out like this:
I've ran this code and compared the results 5+ times and it's always: the start is wrong, username is partly right, password is always right and loginkey is partly right. So the error is recurring and always in the same spot.
Information you should know, the data get's encrypted and saved to a .txt file. The programme will run again and it will try and decrypted it. The Salt and password are saved on another file and those are read and used in the decryption.
There is a similar question on stackoverflow but the answer just says to use Rijndael(so not really an answer), this code is for me to learn and want an answer that isn't 4 lines long.
Code if curious(but it's basically the same as the MSDN document):
Encryption:
static void EncryptFile()
{
string pwd1 = SteamID;//steamID is referring to account ID on Valve Steam
using (RNGCryptoServiceProvider rngCsp = new
RNGCryptoServiceProvider())
{
rngCsp.GetBytes(salt1); //salt1 is a programme variable and will get saved to a file
}
SecureData File = new SecureData(_UserName,_PassWord,_LoginKey);
string JsonFile = JsonConvert.SerializeObject(File); //puts the class into Json format
int myIterations = 1000; //not needed
try
{
Rfc2898DeriveBytes k1 = new Rfc2898DeriveBytes(pwd1, salt1,
myIterations);
Aes encAlg = Aes.Create(); // This might be the issue as AES will be different when you decrypt
encAlg.Key = k1.GetBytes(16);
MemoryStream encryptionStream = new MemoryStream();
CryptoStream encrypt = new CryptoStream(encryptionStream,
encAlg.CreateEncryptor(), CryptoStreamMode.Write);
byte[] utfD1 = new System.Text.UTF8Encoding(false).GetBytes(
JsonFile); //encrypt Data
encrypt.Write(utfD1, 0, utfD1.Length);
encrypt.FlushFinalBlock();
encrypt.Close();
byte[] edata1 = encryptionStream.ToArray();
k1.Reset();
System.IO.File.WriteAllBytes(SecureFile, edata1); //writes encrypted data to file
}
catch (Exception e)
{
Console.WriteLine("Error: ", e);
}
}
Decryption:
static void DecryptFile()
{
string pwd1 = SteamID;
byte[] edata1;
try
{
edata1 = System.IO.File.ReadAllBytes(SecureFile); //reads the file with encrypted data on it
Aes encAlg = Aes.Create(); //I think this is the problem as the keyvalue changes when you create a new programme
Rfc2898DeriveBytes k2 = new Rfc2898DeriveBytes(pwd1, salt1); //inputs from last time carry over
Aes decAlg = Aes.Create();
decAlg.Key = k2.GetBytes(16);
decAlg.IV = encAlg.IV;
MemoryStream decryptionStreamBacking = new MemoryStream();
CryptoStream decrypt = new CryptoStream(
decryptionStreamBacking, decAlg.CreateDecryptor(), CryptoStreamMode.Write);
decrypt.Write(edata1, 0, edata1.Length);
decrypt.Flush();
decrypt.Close();
k2.Reset();
string data2 = new UTF8Encoding(false).GetString(
decryptionStreamBacking.ToArray());//decrypted data
SecureData items = JsonConvert.DeserializeObject<SecureData>(data2); //reformat it out of JSon(Crashes as format isn't accepted)
_UserName = items.S_UserName;
_PassWord = items.S_Password;
_LoginKey = items.S_LoginKey;
}
catch (Exception e)
{
Console.WriteLine("Error: ", e);
NewLogin();
}
}
Class Struct:
class SecureData
{
public string S_UserName { get; set; } //These are variables that are apart of Valve steam Login process
public string S_Password { get; set; }
public string S_LoginKey { get; set; }
public SecureData(string z, string x, string y)
{
S_UserName = z;
S_Password = x;
S_LoginKey = y;
}
}
