orc tool: support for signing SGXS binaries

[ptrus]

This adds support for offline singing of SGX enclaves, removing the need for https://github.com/oasislabs/rust-sgx/tree/ravenac95/sgxs-sign-support-offline-sign

Changes:

• orc sgx-sign-data <bundle.orc> subcommand is added which constructs the SIGSTRUCT and outputs the hash to be signed (this replaces the sgx-sign gendata from the rust-sgx tool).
• orc sgx-set-sig <bundle.orc> <signature.sig> <public_key.pub> is updated so that it accepts the signature (of the SIGSTRUCT hash) and the signing public key. It then constructs the signed SIGSTRUCT and inserts it into the manifest (this replaces the two-step process from before, which used: sgx-sign catsig and orc sgx-set-sig)

At the moment the command flags for configuring the SIGSTRUCT fileds matches arguments in the rust-sgx tool: https://github.com/oasislabs/rust-sgx/blob/79ceb56714234f30576d8ccb61548828cfd934c4/sgxs-tools/src/bin/sgxs-sign.rs#L110-L121

NOTE: The above code says that: "ATTRIBUTES.XFRM and inverse ATTRIBUTEMASK.XFRM fields (default: 0x3/0)", but due to a bug the ATTRIBUTEMASK.XFRM actually defaults to 0x3 (the command ignores the flag) and it uses the default defined here: https://github.com/oasislabs/rust-sgx/blob/79ceb56714234f30576d8ccb61548828cfd934c4/sgxs/src/sigstruct.rs#L80-L84

TODO:

• requires release of oasis-core 22.1.9 with: [BACKPORT/22.1.x] go/common/sgx/sigstruct: Add support for offline signing oasis-core#4860 included
• test the offline signing flow (and compare results with fortanix/rust-sgx@master...oasislabs:rust-sgx:ravenac95/sgxs-sign-support-offline-sign the orc sgx-sign-data should match the sgx-sign gendata)
• add documentation for the offline signing flow

[codecov]

Codecov Report

Merging #1056 (e174385) into main (60136c9) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #1056   +/-   ##
=======================================
  Coverage   68.14%   68.14%           
=======================================
  Files         128      128           
  Lines       11061    11061           
=======================================
  Hits         7537     7537           
  Misses       3492     3492           
  Partials       32       32           

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