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# Claimant model
## **System<sup>CHECKSUM</sup>**:
System<sup>CHECKSUM</sup> is about the claims made by a _data publisher_.
* **Claim<sup>CHECKSUM</sup>**:
_I, data publisher, claim that the data_:
1. has cryptographic hash X
2. can be located using X as an identifier
3. has properties Y (_"ecosystem specific_")
* **Statement<sup>CHECKSUM</sup>**: signed checksum<br>
* **Claimant<sup>CHECKSUM</sup>**: data publisher<br>
The data publisher is a party that wants to publish some data to an
end-user.
* **Believer<sup>CHECKSUM</sup>**: end-user<br>
Belief is based on seeing a valid Statement<sup>CHECKSUM</sup>.
* **Verifier<sup>CHECKSUM</sup>**: any interested party<br>
These parties try to verify the above claims. For example:
* the data publisher itself (_"has my identity been compromised?"_)
* third-parties that want to look further into the data (_"ecosystem
specific_")
* **Arbiter<sup>CHECKSUM</sup>**:<br>
There's no official body. Invalidated claims would affect reputation.
**Example.**
The published data could be an executable binary from a reproducible build. The
ecosystem-specific claim would be that the corresponding source code can be
looked-up in a public database using X as an identifier. A rebuilder would
verify this claim by compiling the source, comparing the hashed output to the
claimed value.
## **System<sup>CHECKSUM-LOG<sup>**:
System<sup>CHECKSUM-LOG</sup> is about the claims made by a _log operator_.
It adds _discoverability_ into System<sup>CHECKSUM</sup>. Discoverability means
that Verifier<sup>CHECKSUM</sup> can see all Statement<sup>CHECKSUM</sup> that
Believer<sup>CHECKSUM</sup> will accept.
* **Claim<sup>CHECKSUM-LOG</sup>**:
_I, log operator, make available:_
1. a globally consistent append-only log of Statement<sup>CHECKSUM</sup>
* **Statement<sup>CHECKSUM-LOG</sup>**: signed tree head
* **Claimant<sup>CHECKSUM-LOG</sup>**: log operator<br>
Possible operators might be:
* a small subset of data publishers
* members of relevant consortia
* **Believer<sup>CHECKSUM-LOG</sup>**:
Believer<sup>CHECKSUM</sup> and
Verifier<sup>CHECKSUM</sup><br>
Belief is based on two factors:
1. seeing a valid Statement<sup>CHECKSUM-LOG</sup>
2. seeing a number of valid Statement<sup>CHECKSUM-WITNESS</sup> from
independent instances on System<sup>CHECKSUM-WITNESS</sup>
A _policy_ defines the exact conditions that must be met.
* **Verifier<sup>CHECKSUM-LOG</sup>**: System<sup>CHECKSUM-WITNESS</sup><br>
Witnesses verify the log's append-only property from their own local
vantage point(s).
* **Arbiter<sup>CHECKSUM-LOG</sup>**:<br>
There is no official body. The ecosystem at large should stop using an
instance of System<sup>CHECKSUM-LOG</sup> if cryptographic proofs of log
misbehavior are preseneted by some Verifier<sup>CHECKSUM-LOG</sup>.
## **System<sup>CHECKSUM-WITNESS<sup>**:
System<sup>CHECKSUM-WITNESS</sup> is about making the claims of a log operator
_trustworthy_.
* **Claim<sup>CHECKSUM-WITNESS</sup>**:
_I, witness, claim that_:
1. System<sup>CHECKSUM-LOG</sup> provides a locally consistent append-only
log
* **Statement<sup>CHECKSUM-WITNESS</sup>**: signed tree head
* **Claimant<sup>CHECKSUM-WITNESS</sup>**: third party<br>
Examples of parties that may take on this role include:
* members of relevant consortia
* non-profits and other reputable organizations
* security enthusiasts and researchers
* log operators (cross-ecosystem)
* monitors (cross-ecosystem)
* a small subset of data publishers (cross-ecosystem)
* **Believer<sup>CHECKSUM-WITNESS</sup>**:
Believer<sup>CHECKSUM</sup> and
Verifier<sup>CHECKSUM</sup><br>
Belief is based on seeing a valid Statement<sup>CHECKSUM-WITNESS</sup>.
* **Verifier<sup>CHECKSUM-WITNESS</sup>**: n/a <br>
Witnesses are trusted parties. Security is based on _strength in numbers_.
* **Arbiter<sup>CHECKSUM-WITNESS</sup>**:<br>
There is no official body. Invalidated claims would affect reputation.
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