Trait KelContinuityChecker 

pub trait KelContinuityChecker {
    // Required method
    fn verify_rotation_continuity(
        &self,
        did: &str,
        pinned_tip_said: &str,
        presented_pk: &[u8],
    ) -> Result<Option<RotationProof>, TrustError>;
}

Trait for verifying rotation continuity from a pinned state to a presented key.

Implemented by auths-id (which owns KEL types). The trust module in auths-core calls this trait without importing auths-id.

Implementation Requirements

The implementation must:

1. Locate the event with SAID == pinned_tip_said in the KEL.
2. Replay forward from that event (not from inception), verifying:
   • Hash chain linkage (each event’s p matches predecessor’s d).
   • Sequence ordering (strict monotonic increment).
   • Pre-rotation commitment satisfaction for rotation events.
   • Event signatures.
3. Confirm the resulting key state’s current key matches presented_pk.

Return Values

• Ok(Some(proof)) if continuity is verified.
• Ok(None) if the pinned tip is not found or the chain doesn’t lead to the presented key.
• Err on internal errors (corrupt KEL, deserialization failure).

Required Methods

fn verify_rotation_continuity( &self, did: &str, pinned_tip_said: &str, presented_pk: &[u8], ) -> Result<Option<RotationProof>, TrustError>

Verify that there is a valid, unbroken event chain from pinned_tip_said to a state whose current key matches presented_pk.

Arguments

• did - The DID being verified (e.g., “did:keri:EXq5…”)
• pinned_tip_said - The SAID of the event at which we last pinned this identity
• presented_pk - The raw public key bytes presented for verification

Returns

• Ok(Some(proof)) - Rotation verified, contains new state to update pin
• Ok(None) - Cannot verify continuity (tip not found, chain broken, key mismatch)
• Err(...) - Internal error (corrupt data, I/O failure)

Implementors