Without having open hardware designs and trusted fabs about the best
   you can do is use as many discrete components as possible and FPGAs
   (whose designs greatly minimize places to hide backdoors). Definitely
   avoid SoCs.
   These guys appear to be using some of the best ideas:
   [1]https://puri.sm/

   On Thu, Apr 26, 2018, 9:11 PM grarpamp <[2]grarpamp@gmail.com> wrote:

     >         "we are working on encrypting the entire ledger using
     Intel
     >         SGX, such that no human has access to the raw unencrypted
     data
     >         "
     "SGX isn't perfect - life is full of tradeoffs, and I'd love to move
     to zero knowledge proofs once the technology has developed further"
     "Intel ME isn't a backdoor - it's just a secondary computer"
     "it's treated as part of the chipset so the tools for doing so were
     given to computer manufacturers, not end users."
     Right, a computer you have no fucking idea what it does,
     what's inside it, what it's software is, or how to own it.
     And you want to put money and secrets on it
     and connect it to the internet? Lol.
     Not that it matters since the entire planet runs
     on completely closed and thus untrustable
     hardware, and software, connected to the internet.
     Sane people would rather trust opensource math
     than closed hardware, or at least call out that
     their worshipped hardware is in fact... closed.
     There's just no excuse for not publicly loudly calling out
     closed shit and demanding #OpenFabs , #OpenHW .
     Instead of doing that, seems like everyone bought
     the "security is number one" kool-aid Intel spun out
     during Meltdown / Spectre / etc. Fools.

References

   1. https://puri.sm/
   2. mailto:grarpamp@gmail.com