What I meant is that any resource we used so far thats different from S40, gives the error. I noticed it since Cassio's S60 resource build when the S40 builds still worked for some.That means the server is expecting some other header we dont know.
No-no, I have tested it for several evenings, and figured out what does it expext

It expects a string in the following format: "Device-1.11.11-433"
A "device" must be one of the following existing headers: "S40", "Symbian", "Android", "iPhone", "BB", and some header for WindowsPhone which I failed to figure out. All of them are accepted by the server and work with encryption.
1.11.11 - is whatsapp client version. I'm not sure about the format, but too old versions are blocked by the server, making the users to update periodically. You can actually set 9.99.99, and it will work.
The last value is a port number. It is not necessary.
Firstly I have figured out that encryption doesn't work if you send incorrect resource (I set "iOS" as device, it worked, and we used it for several days untill they fixed it and the server started blocking all the incorrect resources). And now it is empty resource. That's it

Miranda tell me the message 'blocked'. So I try to Register with the Tool "wart.exe". That tell me same. I don't use whatsapp at my Smartphone.
Seems like a ban indeed. But all the bans so far were temporary as far as I know. Moreover, there was a discussion in the thread about possible ban for not-paying for the service. That's why I suggest trying official client (just to test and make sure). Personally I'm using WhatsApp in Miranda for more than two years now, never payed for it and still not banned. But it is still a trouble we should expect.