Another (non .NET, Oracle) application will be passing my .NET web application data via the QueryString. I was told that this data would be DES encrypted and Base64 encoded.

The problem is that they told me that their encryption package uses only a "key" to perform the encryption....
http://www.lc.leidenuniv.nl/awcourse/oracle/appdev.920/a96612/d_obtoo2.htm

....but the .NET DES object that I expect to use to decrypt the Querystring expects 2 parameters, the original KEY used to encode it plus an Initialization Vector (IV)

http://msdn2.microsoft.com/system.security.cryptography.des.aspx

It seems to me that unless I have the IV, that there is no way that I can decode the Querystring they send me. Any idea?



I saw an example on the web

http://www.devcity.net/Articles/47/1/encrypt_querystring.aspx

which uses the following IV :

Private IV() As Byte = {&H12, &H34, &H56, &H78, &H90, &HAB, &HCD, &HEF}

Since I saw this same IV value in multiple web examples, I thought perhaps for some reason it was commonly used, though using this value along with the key that was provided to me did not yeild a meaningful result.



Any suggestions would be appreciated.

That's correct. You can agree with them on a suitable vector that you would
hard code in if they don't want to pass it to you.

Another (non .NET, Oracle) application will be passing my .NET web
application data via the QueryString. I was told that this data would be DES
encrypted and Base64 encoded.

The problem is that they told me that their encryption package uses only a
"key" to perform the encryption....
http://www.lc.leidenuniv.nl/awcourse/oracle/appdev.920/a96612/d_obtoo2.htm

....but the .NET DES object that I expect to use to decrypt the Querystring
expects 2 parameters, the original KEY used to encode it plus an
Initialization Vector (IV)

http://msdn2.microsoft.com/system.security.cryptography.des.aspx

It seems to me that unless I have the IV, that there is no way that I can
decode the Querystring they send me. Any idea?



I saw an example on the web

http://www.devcity.net/Articles/47/1/encrypt_querystring.aspx

which uses the following IV :

Private IV() As Byte = {&H12, &H34, &H56, &H78, &H90, &HAB, &HCD, &HEF}

Since I saw this same IV value in multiple web examples, I thought perhaps
for some reason it was commonly used, though using this value along with the
key that was provided to me did not yeild a meaningful result.



Any suggestions would be appreciated.

Several years ago I had to do something similar using VB6 and a third party
encryption component. I had to decrypt the querystring data which was
encrypted by a Java application.

I think it was DES (instead of 3DES). They only gave me a PW and said not to
use an IV. I thought it strange but I did so and it worked.

Hope this helps...

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