Re: Assembly.GetExecutingAssembly - can we get "Key" which signed the assembly? [modified] - C# Discussion Boards

2-Mar-11 1:05

That's far too broad a scope for anybody to stand a chance of answering here on the boards. If you narrow the scope of your question, you might get more help. Beyond that, try to google for DirectX tutorials C# and OpenGL tutorials C#.

I'm not a stalker, I just know things. Oh by the way, you're out of milk.

Forgive your enemies - it messes with their heads

Problem in sending sms from pc to mobile through AT commands [modified]

aeman1-Mar-11 23:27

aeman

1-Mar-11 23:27

Hi,

I am using Nokia 6630 for sending sms from my pc to mobile via gsm modem.I have connected all this through serial cable.I am using C# tool but now i have just used the following commands in hyperterminal and it gave following responses:

AT
OK
AT+CMGF=?
+CMGF: (0,1)

OK
AT+CMGF=1
OK
AT+CMGW="0123456789"    //my mobile number
&gt; HI 
+CMGW: 26
OK

Everything is OK but message is not sent to mobile.I dont know where is the problem.Can anyone solve this?? Thanks in advance.

Regards,
Aeman

modified on Wednesday, March 2, 2011 5:43 AM

Re: Problem in sending sms from pc to mobile through AT commands

Thomas Krojer1-Mar-11 23:33

Thomas Krojer

1-Mar-11 23:33

the +CMGW writes the sms to the mobiles memory, you need also something like AT+GMSS= ....

try this:
http://www.developershome.com/sms/howToSendSMSFromPC.asp

I cannot remember: What did I before google?

AppDomain.CurrentDomain.SetData(SOME_SECRET_KEY, PrivateKey) [modified]

devvvy1-Mar-11 22:53

devvvy

1-Mar-11 22:53

Hello

If I set some secret/sensitive information in AppDomain ...
AppDomain.CurrentDomain.SetData(SOME_SECRET_KEY, PrivateKey)

How can I protect it from third party dll loaded on demand? For example, in our application which hosts third party dll,

<br />
MaliciousLib = Assembly.LoadFrom(DllPath);<br />
oService = MaliciousLib.CreateInstance("xxxx.xxxx.xxxx");<br />
ISomeService Service = (ISomeService) oService;<br />
Service.DoSomeWork(...);<br />

Here, MaliciousLib can also access AppDomain and retrieves secret key.

I'm considering loading third party dll's into separate app domain (In which case they can't have access to the main AppDomain right...? In which case, next logical question - how 3rd party lib communicates back to main assembly... while it can't access main assembly's AppDomain variables, perhaps "function call return" would suffice ...)[^]

But I just done some testing, User dll methods can still access AppDomain.CurrentDomain!

<br />
oSecret = AppDomain.CurrentDomain.GetData("KEY1");<br />

Many articles discuss theories surrounding AppDomain, how one process can host multiple AppDomain and disaster occurring in one won't bring down the whole process - but really? Thought that's .NET v1 behavior - from v2 on disaster in one AppDomain will bring down the whole process. Also, regarding Get/SetData from security perspective, there's nothing on Google. From my experiment, there isn't any security control on Get/SetData![^]

So really how to protect main app from loaded third party components? Any suggestion?

dev

modified on Wednesday, March 2, 2011 11:25 PM

Assembly.GetExecutingAssembly - can we get "Key" which signed the assembly?

devvvy1-Mar-11 22:49

devvvy

1-Mar-11 22:49

Hi
Assembly.GetExecutingAssembly - can we get "Key" which signed the assembly?

I examined the internals of Assembly using Visual Studio Watch window, I found properties such as CodeBase, EntryPoint, Evidence, FullName, GlobalAssemblyCache, ImageRuntimeVersion ... but didn't find anything which resembles Key ...

Thanks

dev

Re: Assembly.GetExecutingAssembly - can we get "Key" which signed the assembly?

Keith Barrow1-Mar-11 23:23

Keith Barrow

1-Mar-11 23:23

You can't get the key that signed the assembly. If you could, you'd be able to create your own "fake" assembly and sign it with the key, making it look legitimate. Obviously, this would be a security hole.
You can get the public key as per this article on Stack Overflow.: http://stackoverflow.com/questions/809934/assembly-loadfrom-using-evidence-overload-to-verify-strong-name-signature[^]

Sort of a cross between Lawrence of Arabia and Dilbert.[^]
-Or-
A Dead ringer for Kate Winslett[^]

Re: Assembly.GetExecutingAssembly - can we get "Key" which signed the assembly? [modified]

devvvy2-Mar-11 16:08

devvvy

2-Mar-11 16:08

I just tested, even if User dll loaded and proxy created on a separate AppDomain - User dll methods can still access "AppDomain.CurrentDomain.GetData("KEY1")!

<br />
***** Program.cs ***** <br />
<br />
using System;<br />
using System.Collections.Generic;<br />
using System.Linq;<br />
using System.Text;<br />
<br />
using System.Reflection;<br />
using System.Security.Policy;<br />
<br />
using UserUtil;<br />
using SimpleUtil;<br />
<br />
namespace TestAppDomain<br />
{<br />
    class Program<br />
    {<br />
        public const string KEY1 = "KEY1";<br />
        public static AppDomain UserDomain = null;<br />
<br />
        static void Main(string[] args)<br />
        {<br />
            Assembly UserAssembly = null;<br />
            Object oProvider = null;<br />
            SimpleUtil.IServiceProvider UserProvider = null;<br />
<br />
            try<br />
            {<br />
                AppDomain.CurrentDomain.SetData(KEY1, "PrivateKey");<br />
<br />
                UserDomain = AppDomain.CreateDomain("UserDomain");<br />
                UserDomain.SetData(KEY1, "Sh*t!");<br />
                <br />
                UserAssembly = Assembly.LoadFrom("UserUtil.dll");<br />
                <br />
                oProvider = UserDomain.CreateInstanceFrom("UserUtil.dll", "UserUtil.ServiceProvider").Unwrap();<br />
                // oProvider = UserAssembly.CreateInstance("UserUtil.ServiceProvider");<br />
<br />
                if (oProvider != null)<br />
                {<br />
                    if (oProvider is SimpleUtil.IServiceProvider)<br />
                    {<br />
                        UserProvider = (SimpleUtil.IServiceProvider)oProvider;<br />
<br />
                        UserProvider.DoWork("Calling UserProvider.DoWork");<br />
                    }<br />
                }<br />
            }<br />
            catch (Exception Ex)<br />
            {<br />
                Console.WriteLine(Ex.Message);<br />
            }<br />
<br />
            return;<br />
        }<br />
    }<br />
}<br />
<br />
*** SimpleUtil.ServiceProvider ***<br />
using System;<br />
using System.Collections.Generic;<br />
using System.Linq;<br />
using System.Text;<br />
<br />
using System.Runtime.Serialization;<br />
<br />
namespace SimpleUtil<br />
{<br />
    [Serializable()]<br />
    class ServiceProvider : SimpleUtil.IServiceProvider<br />
    {<br />
        public void DoWork(string Message)<br />
        {<br />
            Console.WriteLine("SimpleUtil.DoWork");<br />
            return;<br />
        }<br />
<br />
        public ServiceProvider()<br />
        {<br />
            return;<br />
        }<br />
<br />
        public ServiceProvider(SerializationInfo info, StreamingContext context)<br />
        {<br />
            return;<br />
        }<br />
<br />
        public void GetObjectData(<br />
            SerializationInfo info,<br />
            StreamingContext context<br />
        )<br />
        {<br />
            return;<br />
        }<br />
    <br />
    }<br />
}<br />
<br />
using System;<br />
using System.Collections.Generic;<br />
using System.Linq;<br />
using System.Text;<br />
<br />
using System.Runtime.Serialization;<br />
<br />
namespace SimpleUtil<br />
{<br />
    public interface IServiceProvider : ISerializable<br />
    {<br />
        void DoWork(string Message);<br />
    }<br />
}<br />
<br />
<br />
***** UserUtil.ServiceProvider *****<br />
using System;<br />
using System.Collections.Generic;<br />
using System.Linq;<br />
using System.Text;<br />
<br />
using System.Runtime.Serialization;<br />
<br />
using SimpleUtil;<br />
<br />
namespace UserUtil<br />
{<br />
    [Serializable()]<br />
    public class ServiceProvider : SimpleUtil.IServiceProvider<br />
    {<br />
        public void DoWork(string Message)<br />
        {<br />
            object oSecret = null;<br />
            string secret = null;<br />
<br />
            oSecret = AppDomain.CurrentDomain.GetData("KEY1");<br />
            if (oSecret != null)<br />
            {<br />
                secret = (string)oSecret;<br />
                Console.WriteLine("UserUtil.DoWork - secret=" + secret);<br />
            }<br />
            else<br />
            {<br />
                Console.WriteLine("UserUtil.DoWork - secret=NULL!");<br />
            }<br />
            return;<br />
        }<br />
<br />
        public ServiceProvider()<br />
        {<br />
            return;<br />
        }<br />
<br />
        public ServiceProvider(SerializationInfo info, StreamingContext context)<br />
        {<br />
            return;<br />
        }<br />
<br />
        public void GetObjectData(<br />
            SerializationInfo info,<br />
            StreamingContext context<br />
        )<br />
        {<br />
            return;<br />
        }<br />
    }<br />
}<br />
<br />

So, this is not going to work if intention of loading third party dll into separate appDomain is security. Not to mention, there are ways to enumerate app domains in the executing process[^]

Any suggestion how we can save sensitive data in AppDomain (using SetData/GetData) "safely"!?

Thanks

dev

modified on Wednesday, March 2, 2011 10:42 PM

How to block read / write operation of cd/dvd [modified]

Aisha sharma1-Mar-11 22:24

Aisha sharma

1-Mar-11 22:24

thanx....

modified on Wednesday, March 2, 2011 5:23 AM

Re: How to block read / write operation of cd/dvd

Keith Barrow1-Mar-11 22:55

Keith Barrow

1-Mar-11 22:55

Do not repost[^], it is rude. This might be urgent for you, but not for the people who volunteer their time.

Sort of a cross between Lawrence of Arabia and Dilbert.[^]
-Or-
A Dead ringer for Kate Winslett[^]

Re: How to block read / write operation of cd/dvd

Dalek Dave7-Mar-11 11:22

Dalek Dave

7-Mar-11 11:22

Thanks for what?

------------------------------------

I will never again mention that I was the poster of the One Millionth Lounge Post, nor that it was complete drivel. Dalek Dave

CCC Link[^]
Trolls[^]

Load picture from resource file with XAML

Mc_Topaz1-Mar-11 21:25

Mc_Topaz

1-Mar-11 21:25

I would like to display a picture in my WPF application, where the picture is loaded from a resource file. I'm not interesting doing this with C# code, only with XAML code. But I have no idéa how to pull this off. Please help me.

This is what I have done:

1) Created a new WPF application called: WpfApplication1
2) Created a resource file called: Pictures.resx
3) Added the picture into the resource file
4) The picture is called: CELabel, in the resoruce file explorer window
5) Automatically a folder in in my application is created, called Resources, containing the picture: CELabel.png

Now I would like to code the appropriate XAML code to display the picture. So I try this:

<Window x:Class="WpfApplication1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <Image Source="/Pictures/CELabel.png"></Image>
    </Grid>
</Window>

And of course the damn compiler results in an error:
Could not find a part of the path 'C:\Pictures\CELabel.png'

Yes, of course the resource file is not recognizable in the XMAL editor and then my picture cannot be loaded.
How do I pull this off? I'm sure this is rediculious easy when knowing how...

Re: Load picture from resource file with XAML

Pete O'Hanlon1-Mar-11 21:31

1-Mar-11 21:31

You've stated you don't want to do this in C#, so why ask it in the C# forum? You should ask WPF questions in the WPF forum.

I'm not a stalker, I just know things. Oh by the way, you're out of milk.

Forgive your enemies - it messes with their heads

Re: Load picture from resource file with XAML

Mc_Topaz1-Mar-11 21:36

Mc_Topaz

1-Mar-11 21:36

Wopsi...

Re: Load picture from resource file with XAML

ltuljo2-Mar-11 14:46

ltuljo

2-Mar-11 14:46

Topaz you 're missing the point with usage of Resource.rsx. Just create folder, put a picture in it , drag a image control to your form in properties set path to your picture and that's it!
cheers

Postgres database connection

Software20071-Mar-11 9:32

1-Mar-11 9:32

I am new to databases and C#. In my main program in C#, I can open a connection to postgresdb , do some queries and close connection afterwards. But, I don't like to open it up every time I query the db, is there a way where the db stays opened for the life of the application, so I can query things anytime through out the life of the program and only close when I kill the app.... How is it normally done in big apps that query db quite often?

Is this the right way of doing it, or am i missing something here?

Thanks

Orcun Iyigun1-Mar-11 9:38

Orcun Iyigun

1-Mar-11 9:38

You can do it by database pooling.

See this link to get more info about it;

http://msdn.microsoft.com/en-us/library/8xx3tyca.aspx[^]

In fact closing the connection is recommended. Here is a quote from the documentation:

It is recommended that you always close the Connection when you are finished using it in order for the connection to be returned to the pool. This can be done using either the Close or Dispose methods of the Connection object. Connections that are not explicitly closed might not be added or returned to the pool. For example, a connection that has gone out of scope but that has not been explicitly closed will only be returned to the connection pool if the maximum pool size has been reached and the connection is still valid.

Software20071-Mar-11 9:45

1-Mar-11 9:45

Thanks for the article. It sounds a bit expensive and kinda boring though, so if my app has to access the db 100 times, then I would have 100 connections and closes! Yikes!

Dave Kreskowiak1-Mar-11 9:46

Dave Kreskowiak

1-Mar-11 9:46

So? If you're hogging a $1,000 license and not using it, your manager goes "Yikes!", not you.

A guide to posting questions on CodeProject[^]

Dave Kreskowiak

Dave Kreskowiak1-Mar-11 9:45

Dave Kreskowiak

1-Mar-11 9:45

Software2007 wrote:
I can open a connection to postgresdb , do some queries and close connection
afterwards. But, I don't like to open it up every time I query the db

Tough. That's the "best practice" method to use.

Software2007 wrote:
is there a way where the db stays opened for the life of the application, so I
can query things anytime through out the life of the program and only close when
I kill the app

Bad idea. Database connection licenses are expensive. So, to minimize costs, you are expected to open the connection, use it, then close it as soon as possible so another application can use the connection license on the server.

Think about it. You open a connection for the life of your app, then your app crashes or the network connection goes down, but the SQL connection is never released. Now you've got a connection license being used on the server, but never being used until it's cleared out manually or the connection times out on the server for inactivity.

Software2007 wrote:
How is it normally done in big apps

Open the connection, query it, close it.

A guide to posting questions on CodeProject[^]

Dave Kreskowiak

Software20071-Mar-11 9:56

1-Mar-11 9:56

thanks for the clarification. Again, I am a newbie to db stuff, but in my little brain, I was thinking may be they have soft/virtual connections or something like that where it wouldn't be so expensive and dramatic. I must have been living in fantasy land!
Thanks again

Pete O'Hanlon1-Mar-11 9:56

1-Mar-11 9:56

Software2007 wrote:
am i missing something here?

Big style. It's called scalability. Database connections are expensive resources, and should be treated as precious resources.

Software2007 wrote:
But, I don't like to open it up every time I query the db

So, laziness is a virtue in your world?

Software2007 wrote:
In my main program in C#, I can open a connection to postgresdb , do some queries and close connection afterwards.

Is it a desktop application? If it's a web application then you can't do this anyway, so you might as well get used to the idea of acquiring the connection at the last minute and releasing it as soon as possible.

Here's a poser for you. Suppose you open your connection at the start of your application and your code relies on this connection being open. Now, suppose that the database crashes and restarts between you querying it. What do you think will happen the next time you issue a query? If you guessed that the code will fail, go to the top of the class. If you think you can rely on the connection always being available, slap yourself around the head with a pink halibut and call yourself Ethel.

I'm not a stalker, I just know things. Oh by the way, you're out of milk.

Forgive your enemies - it messes with their heads

Software20071-Mar-11 10:26

1-Mar-11 10:26

Good answers. I knew the whole costly issue and the concequences of crashing while executing, but I was hoping that I was wrong and there was a more efficient way.

Pete O'Hanlon1-Mar-11 10:34

1-Mar-11 10:34

Write yourself a wrapper class that opens up the connection for you when you execute your SQL if you're worried about remembering to do this.

I'm not a stalker, I just know things. Oh by the way, you're out of milk.

Forgive your enemies - it messes with their heads

Software20071-Mar-11 10:40