Moving read_nvram(...) into XTT library

[kathrynfejer]

While implementing support of XTT for enftun, we realized that read_nvram and other functions may be able to move into the xtt library.

read_nvram currently creates a TCTI context each time it reads from the TPM. Is it possible that we could create a function to do that once, and then use that context/credentials to read out the information?

[drbild]

@kathrynfejer Could you split this into three separate issues, one for read_nvram, one for defining the "context" formats, and one for making the group_context stuff more object-oriented.

That will be easier for discussions. It's fine to reference one from the other.

[zanebeckwith]

This can now be implemented by moving the nvram.[h,c] code from xaptum-tpm into this project.

That should live in the xaptum/tpm namespace, and use the handles defined in xaptum/tpm/handles.h. The client code should then be refactored to create a TPM system context once, and pass it to the xtt_tpm_read_object (previouslyxtpm_read_object) function for each NVRAM "object" it needs to read out.