<div class="gmail_quote">---------- Forwarded message ---------- From: "Randy Bush" <<a href="mailto:randy@psg.com">randy@psg.com</a>> Date: 8 Sep 2015 2:29 pm Subject: Re: Cryptech HSM enquiry To: "Thotheolh Tay" <<a href="mailto:twzgerald@gmail.com">twzgerald@gmail.com</a>> Cc: > I noticed that the Novena board was used as the HSM. That means the use of > ARM and probably Xilinx were used. > > 1.) May I know how the secret keys are stored ? > > 2.) I would like to know if inter-bus communications are encrypted and > signed as well ? > > 3.) Tamper resistance keystorage can be provided by smartcards or SIM cards > in your Alpha board model. A JavaCard enabled smartcard may accept certain > smartcard protocols to process the secret key instead of using a > power-backed memory chip that is not tamper resistance. > > The weakness of the Alpha board design in regards to tamper is it needs to > protect the entire board instead of just a chip and a huge net might be > less effective and efficient than a protected chip. Thus, the use of > smartcard(s) in such a place for the master key would be advantageous. > > The master key can unwrap a subordinate key and pass it to the FPGA or ARM > chip which you now only need to wrap the two chips and RTC in tamper > shields and pot. The inter-bus can be left exposed as long as chips are > using end-to-encryption and signing of bus messages. > > The exposed physical and logical interfaces must logically be protected at > least via Diffie-Hellman sessions and even better with the HSM's Root Cert. > > Things like equipping an attached display and keyboard or scroll wheel must > also be secured via the display unit having it's own crypto chip and same > for the scroll wheel and keyboard to ensure end-to-end security. > > The problem left is secure and trusted bootloading. Not trusting the ARM > TrustZone or FPGA to do the trusted boot is a wise choice to prevent > certain backdoors. This is by far the hardest problem which would take > sometime to solve without really needing to trustvthe secure boot baked > into chips due to backdoor concerns. could you please repost this to <a href="mailto:tech@cryptech.is">tech@cryptech.is</a>? thanks. randy </div>