>I am trying to store username & password in isolated storage. I have no issue when I use plain test, but I have now added encryption to the password and can not get it to decrypt when I read it back.
>
>The code is run from a form which has 2 testboxes on txtUserName and txtPassword, the writing of the password to isolated storage works fine, it's when I try and decrypt the password, the problem appears to be;
>
>CryptoStream myCryptoStream = new CryptoStream(myMemoryStream,cryptoKey.CreateDecryptor(), CryptoStreamMode.Read);
>
>
>MyMemoryStream has a length of 28, but querying the length of myCryptoStream shows
>
>Length = 'myCryptoStream.Length' threw an exception of type 'System.NotSupportedException'
>
>
>And then the code calls over on
>
>string myPlainText = myStreamReader.ReadToEnd();
>
>
>With an "invalid Length" error.
>
>Any ideas? Full code below
>
>Gary.
>
>
>
>
> private void WriteUserLogon()
> {
> //create a store stream
> IsolatedStorageFile myStorage = IsolatedStorageFile.GetUserStoreForAssembly();
> IsolatedStorageFileStream userStream = new IsolatedStorageFileStream("Logon.dat", System.IO.FileMode.OpenOrCreate);
>
> String userPassword_Encrypted = Cryptography.EncryptString(txtPassword.Text);
> StreamWriter userLogonStream = new StreamWriter(userStream);
> userLogonStream.WriteLine("<UserName>" + txtUserName.Text + "</UserName>");
> userLogonStream.WriteLine("<Password>" + userPassword_Encrypted + "</Password>");
> userLogonStream.Close();
> userStream.Close();
> myStorage.Close();
>
> private void ReadUserLogon()
> {
> //create a store stream
> IsolatedStorageFile myStorage = IsolatedStorageFile.GetUserStoreForAssembly();
> IsolatedStorageFileStream userStream = new IsolatedStorageFileStream("Logon.dat", System.IO.FileMode.OpenOrCreate);
>
> StreamReader userLogonStream = new StreamReader(userStream);
> String logonData = userLogonStream.ReadToEnd();
> userLogonStream.Close();
> userStream.Close();
> myStorage.Close();
>
> if(logonData.IndexOf("UserName")>0)
> {
> int startPos = logonData.IndexOf("<UserName>")+10;
> int endPos = logonData.IndexOf("</UserName>");
> String userName = logonData.Substring(startPos , endPos-startPos);
>
> txtUserName.Text = userName;
> }
>
> if (logonData.IndexOf("Password") > 0)
> {
> int startPos = logonData.IndexOf("<Password>") + 10;
> int endPos = logonData.IndexOf("</Password>");
> String userPassword_Encrypted = logonData.Substring(startPos, endPos - startPos);
> String userPassword = Cryptography.DecryptString(userPassword_Encrypted);
> txtPassword.Text = userPassword;
> }
>
> }
>
>public static byte[] Encrypt(string myPlainText)
> {
> MemoryStream myMemoryStream = new MemoryStream();
> DESCryptoServiceProvider cryptoKey = new DESCryptoServiceProvider();
> CryptoStream myCryptoStream = new CryptoStream(myMemoryStream, cryptoKey.CreateEncryptor(), CryptoStreamMode.Write);
> StreamWriter myStreamWriter = new StreamWriter(myCryptoStream);
> myStreamWriter.WriteLine(myPlainText);
> myStreamWriter.Close();
> myCryptoStream.Close();
> byte[] myBuffer = myMemoryStream.ToArray();
> myMemoryStream.Close();
> return myBuffer;
>
> }
> public static string Decrypt(byte[] myCryptoText)
> {
> MemoryStream myMemoryStream = new MemoryStream(myCryptoText);
> DESCryptoServiceProvider cryptoKey = new DESCryptoServiceProvider();
> CryptoStream myCryptoStream = new CryptoStream(myMemoryStream, cryptoKey.CreateDecryptor(), CryptoStreamMode.Read);
>
> StreamReader myStreamReader = new StreamReader(myCryptoStream);
>
>//Next Line Fails
> string myPlainText = myStreamReader.ReadToEnd();
>
> myStreamReader.Close();
> myCryptoStream.Close();
> myMemoryStream.Close();
> return myPlainText;
>
> }
>
>Maybe haven't looked closely enough but I think you either have to use the same instance of CryptoStream for encrypting and decrypting or pass the same key value as a CreateDecryptor() parameter in both constructors. If that needs clarifying please let me know..
