Essential Functions: getLocalIp() and ByteArToHex()

That I don’t want to re-write in case my hard drive breaks, all public domain:

Private Function getLocalIp() As String

        Dim myips As Net.IPHostEntry = System.Net.Dns.GetHostEntry(Net.Dns.GetHostName)

        Dim myip As String = “127.0.0.1”

        For Each ipaddress As Net.IPAddress In myips.AddressList
            If ipaddress.ToString.Split(“.”).Count = 4 Then
                If ipaddress.ToString <> “127.0.0.1” Then
                    myip = ipaddress.ToString
                    Exit For
                End If
            End If
        Next

        Return myip

    End Function

 

---

 

    Private Function ByteArToHex(ByVal byteAr As Byte())
        Dim s1 As String = “”
        For Each c1 As Byte In byteAr
            s1 = s1 + String.Format(“{0:X2}”, c1)

        Next
        Return s1

    End Function

 

---

 

Possible bugs in Visual Studio 2010 and WordPress

On wordpress first:
I get followers and likes even though I have no views during the day and block viewers from reading the whole text on “reader”

On visual studio:
If one creates a raw socket, it doesn’t receive data from tcp/udp requests(neither from visual studio nor firefox)
If you create a non-blocking udp server, and try to modify a control without invoke the program simply closes without raising errors(It didn’t happen with the asynchronous tcp server I built yesterday)
About raw sockets again, it says on the tooltip that you need to create your own ip header, in practice it sends the header by itself.

Cryptography #2

So, it turns out I couldn’t generate public keys from private ones using Diffie-Hellman algorithm, it took several minutes for even a limited size private key.

In the end I went back to visual basic and after lots of researching(thanks stackoverflow) I got a handle on how to extract(export) private and public keys.
That may be unnecessary though, I can simply send a signature with the algorithm I’m using(one called “ECDsa”). If I were to save the private key I’d need to authorize it at object(Security.Cryptography.CngKey) instantiation.

EDIT:
I need to send the public key even if I have a signature. No idea why I said I didn’t need to. I spent most of the previous days trying to accomplish just that.

Cryptography

Asides from GUI this seems to be the second major weakness in python. No public/private key generator. To make things worse, visual studio documentation doesn’t seem simple either. It has all stuff I probably need but it’s confusing. Does CngKey refers to a public or private key? And how do I store it in a plain text file?

Here is what I really needed:

getPrivateKey()
Gets a new private key that is random/prime/secure/etc

getPublicKey(privateKey)
Gets the matching public key

getSharedSecret(privateKey,friendPublicKey)
Gets a shared secret(that I’ll use in a keyed hash, like hmac)

Done. I could implement that in Python but I am 99% sure I would make a serious mistake and expose the private key.

I don’t want a certificate or to associate either key or the shared secret with any company or person. Just to have that link between private and public key.

P2P in Visual Studio 2010

I was having trouble making my server/client(it is going to be a node) communicate with firefox(for purposes of testing), I wasted some time learning what “hole punching” is and even thought I was going to have an uphill battle with this issue. Alas, VB has a TcpListener with the following function: AllowNatTraversal. All you need to do is to bind your external IP address on your TcpListener and then call AllowNatTraversal(True). Done. You can now receive stuff from the client 😀

Thank you Bill Gates.

Now, on a side note, how do they do it? Last time I checked “hole punching” required a non-firewalled server and didn’t work very well trough TCP. Hmmmm. Perhaps some other method of NAT traversing? I hope I’m not building something that will rely on a centralized server. It would kill the point of having P2P.

Whoa, “new” components!

Great tip for you if you are using Visual Studio 2010, right click the component toolbox and click “Choose items”