feat: add marshal/unmarshall to command/response

[loicsikidi]

a naive implementation of Command/Response marshalling in order to address #414

I'm open to feedback if there a better way to provide this feature.

[loicsikidi]

@chrisfenner once this PR will be approved it will be required to squash because latest commit messages won't be useful.

[chrisfenner]

This is looking really awesome! I have a few more comments to try to drive down the complexity of this solution and maximize the usability, but I think we're really close. Thanks for incorporating my feedback!

[loicsikidi]

Hi @chrisfenner sorry for the delay,

I've added 3 atomic commits to address your latest feedbacks.

• 6842806 :
  • refactor CommandPreimage's marshal/unmarshal
  • add comments to say that we currently don't support encrypted params
  • remove ToCPHashPreimage()
• bb5085e : deduplicate unmarshalparameter logic. WDYT?
• 9b4e0b3 : refactor populateHandlesFromNames

[chrisfenner]

Thanks for your patience on my review, @loicsikidi -- your reply came in while I was at a conference, and then I have been out sick the past week. I think we are very close here, just a couple more things to make sure that this satisfies your original use case of making it as easy as possible for users to compute cpHash/rpHash for audit- and audit-adjacent TPM activities.

[loicsikidi]

As agreed I've refactored Marshal/Unmarshal.

Command

cmdData, err := MarshalCommand(myCmd)
// handle err
cpHash := sha256.Sum256(cmdData)
// do something interesting with cpHash

Response

rspData, err := MarshalResponse(myCmd, myRsp)
// handle err
rpHash := sha256.Sum256(rspData)
// do something interesting with rpHash

I'm waiting for your feedbacks.

PS: I see the light at the end of the tunnel 😄

[loicsikidi]

@chrisfenner

I need to get the Command Code as an input.

I think that it's more natural to pass the command but maybe that TPMCC is better.

WDYT?

[chrisfenner]

I think what you've written is perfect. Very natural. Thanks!

[chrisfenner]

Thanks so much for this change and for incorporating the feedback!

[chrisfenner]

I think what you've written is perfect. Very natural. Thanks!

[chrisfenner]

Thank you @loicsikidi for this change! I'm very happy with how the feature turned out. I appreciate your willingness to entertain my many comments :)