Getting current MachineKey, or equivilent, for HMAC (in web-farm)

Question

I am using HMACSHA256 for message authentication in a web-farm environment.

Within the web-farm each machine has the same machine key, so the ViewState will work acr

Answer 1

You can read the machine key from the web.config. This link shows how to do so: http://aspnetresources.com/blog/how_to_read_auto_generated_machinekey

Keep in mind, that the author of the article reads the generated machine key - so you have to do some changes in the code.

I just read the article a little bit more and saw, that it uses reflection, which isn't neccessary, if you store the machine key inside the web.config. Essentially it breaks down to this line:

MachineKeySection section = (MachineKeySection) 
  ConfigurationManager.GetSection ("system.web/machineKey");