# Claimant model
## **SystemCHECKSUM**:
SystemCHECKSUM is about the claims made by a _data publisher_.
* **ClaimCHECKSUM**:
_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_")
* **StatementCHECKSUM**: signed checksum
* **ClaimantCHECKSUM**: data publisher
The data publisher is a party that wants to publish some data to an
end-user.
* **BelieverCHECKSUM**: end-user
Belief is based on seeing a valid StatementCHECKSUM.
* **VerifierCHECKSUM**: any interested party
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_")
* **ArbiterCHECKSUM**:
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.
## **SystemCHECKSUM-LOG**:
SystemCHECKSUM-LOG is about the claims made by a _log operator_.
It adds _discoverability_ into SystemCHECKSUM. Discoverability means
that VerifierCHECKSUM can see all StatementCHECKSUM that
BelieverCHECKSUM will accept.
* **ClaimCHECKSUM-LOG**:
_I, log operator, make available:_
1. a globally consistent append-only log of StatementCHECKSUM
* **StatementCHECKSUM-LOG**: signed tree head
* **ClaimantCHECKSUM-LOG**: log operator
Possible operators might be:
* a small subset of data publishers
* members of relevant consortia
* **BelieverCHECKSUM-LOG**:
BelieverCHECKSUM and
VerifierCHECKSUM
Belief is based on two factors:
1. seeing a valid StatementCHECKSUM-LOG
2. seeing a number of valid StatementCHECKSUM-WITNESS from
independent instances on SystemCHECKSUM-WITNESS.
* **VerifierCHECKSUM-LOG**: SystemCHECKSUM-WITNESS
Witnesses verify the log's append-only property from their own local
vantage point(s).
* **ArbiterCHECKSUM-LOG**:
There is no official body. The ecosystem at large should stop using an
instance of SystemCHECKSUM-LOG if cryptographic proofs of log
misbehavior are preseneted by some VerifierCHECKSUM-LOG.
## **SystemCHECKSUM-WITNESS**:
SystemCHECKSUM-WITNESS is about making the claims of a log operator
_trustworthy_.
* **ClaimCHECKSUM-WITNESS**:
_I, witness, claim that_:
1. SystemCHECKSUM-LOG provides a locally consistent append-only
log
* **StatementCHECKSUM-WITNESS**: signed tree head
* **ClaimantCHECKSUM-WITNESS**: third party
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)
* **BelieverCHECKSUM-WITNESS**:
BelieverCHECKSUM and
VerifierCHECKSUM
Belief is based on seeing a valid StatementCHECKSUM-WITNESS.
* **VerifierCHECKSUM-WITNESS**: n/a
Witnesses are trusted parties. Security is based on _strength in numbers_.
* **ArbiterCHECKSUM-WITNESS**:
There is no official body. Invalidated claims would affect reputation.