[Rats] Propose a new event-log-type in CHARRA

["Panwei (William)" <[e-mail]>]

Hi authors, all,

We've proposed a new attested-event-log-type in the Github (PR#5<https://github.com/ietf-rats-wg/basic-yang-module/pull/5>) a while ago, but unfortunately there is little discussion about it. This is also mentioned at IETF 108 meeting. I think it might be better to bring this topic to the mailing list and give more description about it.
The blue part below is the format of the new type of log that we propose. It literally looks somewhat similar to the IMA log format, because it uses part of the IMA's concepts in the devices boot measurement.
When the device boots, it needs to load/execute a lot of files, but the order in which these files are loaded/executed is not deterministic or hard to keep fixed, so it's difficult to give an accurate reference value.
The method to overcome this difficulty is below:
1. The Attester measures each file before execution, extends the hash value of the file into PCR, and records the measurement information of the file in the log.
2. When doing the remote attestation, the Attester sends the final values of the PCRs and the detailed logs to the Verifier.
3. The Verifier has a list of reference values for all files. It compares the hash value of each file recorded in the log with the corresponding reference value. If all files' hash values match with their reference values, then the Verifier extends the hash values one by one according to the order recorded in the log, gets the final value, and compares the final value with the PCR value sent by the Attester.
Based on this method, we propose the new type of log. Any thoughts?

+--ro output
   +--ro system-event-logs
      +--ro node-data* []
         +--ro tpm-name?     string
         +--ro up-time?      uint32
         +--ro log-result
            +--ro (attested-event-log-type)
               +--:(bios)
               |  +--ro bios-event-logs
               |     +--ro bios-event-entry* [event-number]
               |        +--ro event-number    uint32
               |        +--ro event-type?     uint32
               |        +--ro pcr-index?      pcr
               |        +--ro digest-list* []
               |        |  +--ro hash-algo?   identityref
               |        |  +--ro digest*      binary
               |        +--ro event-size?     uint32
               |        +--ro event-data*     uint8
               +--:(netequip-boot)
               |  +--ro boot-event-logs
               |     +--ro boot-event-entry* [event-number]
               |        +--ro event-number               uint64
               |        +--ro filename-hint?             string
               |        +--ro filedata-hash?             binary
               |        +--ro filedata-hash-algorithm?   string
               |        +--ro file-version?              string
               |        +--ro file-type?                 string
               |        +--ro pcr-index?                 pcr
               +--:(ima)
                  +--ro ima-event-logs
                     +--ro ima-event-entry* [event-number]
                        +--ro event-number               uint64
                        +--ro ima-template?              string
                        +--ro filename-hint?             string
                        +--ro filedata-hash?             binary
                        +--ro filedata-hash-algorithm?   string
                        +--ro template-hash-algorithm?   string
                        +--ro template-hash?             binary
                        +--ro pcr-index?                 pcr
                        +--ro signature?                 binary

Regards & Thanks!
Wei Pan