Slowass license provider

[Nak]

Hi there,

I just made my own license provider (at last!) that uses signed XML
license files. When the license provider gets the license it does the
following,

*At runtime

1) Gets the signed XML license file from the calling assemblys resources
2) Gets the public RSA key from the calling assemblys resources
3) Attempts the validate the signature

*At design time

1) Gets the signed XML license file from same path the binary is
executing from (i.e. Obj\Debug or Obj\Release)
2) Gets the public RSA key from same path the binary is executing from
(i.e. Obj\Debug or Obj\Release)
3) Attempts the validate the signature

This works fine, and it seems to be quite a reliable method of control
licensing with 1 exception. It's damn slow!

Check this out, I timed the creation and disposal of 2 types of control,
1 licensed via my method and 1 not licensed at all. I timed how many could
be created in 1 minute in both circumstances and these were my results,

* I created 3,456,717 un-licensed controls in 1 minute

* I created 438 licensed controls in 1 minute

On closer inspection it turns out that the GetLicense method starts at
about 578ms then jumps around 94ms and 250ms each time. So obviously this
greatly reduces the speed of creating large numbers of controls. I would
ideally like to speed this up and I believe that there is a way to cache the
license file and possibly the public key too.

So that leaves me asking if anyone has any idea how I can create my own
LicenseContext class and get it passed to my license provider so that I can
use the SetSavedLicenseKey and the GetSavedLicenseKey methods (unless of
course there is another way around this). I have found an example from the
Windows Forms web site that creates a licensed component class, but I'm not
quite sure if this is what I need or not as this would intil creating lots
of derived classes from the licensed one.

Anyways, thanks for your time and I look forward to any suggestions!

Nick.

 

[Peter Huang]

Hi Nick,

Here is the link about create customlicensecontext, you may take a look.
http://www.windowsforms.net/Samples/download.aspx?PageId=1&ItemId=123&tabind
ex=4

Best regards,

Peter Huang
Microsoft Online Partner Support

Get Secure! - www.microsoft.com/security
This posting is provided "AS IS" with no warranties, and confers no rights.

 

[Nak]

Hi Peter,

<quote>...
"I have found an example from the Windows Forms web site that creates a
licensed component class, but I'm not
quite sure if this is what I need or not as this would intil creating lots
of derived classes from the licensed one."

I know it was a bit of a long question so never mind. I think I have
just found out something quite interesting. *ALL* Licensed objects via a
license provider are "slowass" at being created in comparrison to unlicensed
controls, which would explain any bottle necks in my application. My PC is
making around 749,862 standard LicFileLicenseProvider licensed controls in 1
minute too.

I have thought of 1 idea to help speed up the process but it doesnt seem
to make any difference, I have created a custom attribute that allows you to
specify the public key to verify the XML file with, it seems that retrieving
data from an assemblys resources actually takes very little time. So at
the moment I am looking for another bottle neck and all I can think it is;
is that the license key for that type is *not* being cached, if it were it
would take very little to no time at all to create the 2nd object.

I *think* this is all the licene context does, *but* the example on
Windows Forms does *not* use a license provider and I must as I am wanting
to license any class via my own license provider so that I can in-turn sell
this product as a licensing solution. Surely other XML based licensing
systems arent this slow so it must be something I'm missing! :-(

Nick.

 

[Nak]

Hi again,

Even more scary results, I have managed to implement a custom
LicenseContext by altering the license managers context when my application
loads, now it caches the resource file in the form of a string in a
hashtable and the public key is passed via a custom attribute but it is
*still* as slow as a sloath swimming in molasses! So this leads me to
believe that it is the XML signature verification that is slow, this is my
routine,

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

Private Function verifyViaString(ByVal iType As Type, ByVal iLicense() As
Byte, ByVal iPublicKey As String) As Boolean
Try

'Firstly we load the XML license from a byte array into a memory
stream

Dim pMSmInput As New MemoryStream(iLicense)

'Then we load it into the XML document object

Dim pXDtXMLDoc As New XmlDocument()
Call pXDtXMLDoc.Load(pMSmInput)

'Then we create a new signature object

Dim pSXlSigned As New SignedXml(pXDtXMLDoc)
Dim pXNeSig As XmlNode =
pXDtXMLDoc.GetElementsByTagName("Signature",
SignedXml.XmlDsigNamespaceUrl)(0)
Call pSXlSigned.LoadXml(CType(pXNeSig, XmlElement))

'Then we set the public key to verify with

Dim pStrKey As String = iPublicKey

'The following check is used as an internal precauting within my
application

If (Not (pStrKey Is Nothing)) Then

'Then we create the CSP object to verify the signature with

Dim pRSACrypto As RSACryptoServiceProvider = New
RSACryptoServiceProvider()
Call pRSACrypto.FromXmlString(pStrKey)

'Lastly we verify the signature

If (pSXlSigned.CheckSignature(pRSACrypto)) Then
Return (True)
End If
End If
Finally
End Try
End Function

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

My understanding is that this is as fast as this method could possibly
be, but surely slowing it down as much as it is is not a viable solution.
Has anyone any ideas on how I can speed this little method up maybe? Or an
alternative method?

Nick.

 

[Nak]

AAaaah, and dumb I surely am!

I was caching the license keys in the context but still verifying them, and
in theory if a license key has already been verified in order to be cached
there is no point in verifying it again, so I just create a new license with
that key and return it straight away! Bobs your aunty or whatever and now
over 1 million licensed controls per minute! ;-)

Nick.

 

[Peter Huang]

Hi Nick,

It is cool that you have resolved the problem.
Cheers!

Best regards,

Peter Huang
Microsoft Online Partner Support

Get Secure! - www.microsoft.com/security
This posting is provided "AS IS" with no warranties, and confers no rights.