go/common/node: Add runtime encryption key (REK)

[peternose]

Used attestation signature to authenticate the REK. When computing the signature the new version hashes also REK.

Next (optional) step would be to:

• move height and signature to CapabilitiesTEE,
• define custom CBOR marshalling which would copy those two fields from the SGXAttestation v2, and
• move signature verification to CapabilitiesTEE.

We would probably also need to introduce versioning for CapabilitiesTEE. As this step is more complicated and not needed, I decided to skip it.

[codecov]

Codecov Report

Merging #5125 (9c8fb59) into master (1e625b6) will increase coverage by 0.01%.
The diff coverage is 72.72%.

❗ Current head 9c8fb59 differs from pull request most recent head cf222c2. Consider uploading reports for the commit cf222c2 to get more accurate results

@@            Coverage Diff             @@
##           master    #5125      +/-   ##
==========================================
+ Coverage   66.83%   66.85%   +0.01%     
==========================================
  Files         496      496              
  Lines       53271    53275       +4     
==========================================
+ Hits        35606    35619      +13     
+ Misses      13331    13314      -17     
- Partials     4334     4342       +8     

Impacted Files	Coverage Δ
...o/consensus/tendermint/apps/scheduler/scheduler.go	72.86% <0.00%> (ø)
go/roothash/api/commitment/txnscheduler.go	50.00% <0.00%> (ø)
go/runtime/host/protocol/types.go	54.54% <ø> (ø)
go/common/node/node.go	71.07% <50.00%> (ø)
go/common/node/sgx.go	78.26% <100.00%> (+0.38%)	⬆️
go/runtime/host/sgx/sgx.go	72.27% <100.00%> (+0.27%)	⬆️
go/runtime/txpool/check_queue.go	86.48% <0.00%> (-13.52%)	⬇️
go/runtime/host/protocol/connection.go	64.28% <0.00%> (-6.02%)	⬇️
go/p2p/rpc/client.go	77.97% <0.00%> (-4.41%)	⬇️
go/common/sgx/common.go	66.01% <0.00%> (-3.89%)	⬇️
... and 27 more

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.