C2 Forum — Nonce and State Review
Summary
A source-assisted review of nonce tracking and concurrent state updates in the signature-validation path.
Document record
- Author
- Eduardo Camarillo [Noir0x63]
- Published
- Version
- v1.0
- Language
- English
Validation path
The reviewed flow verified a signature and then consulted in-memory state to determine whether a nonce had already been accepted. State expiry and concurrent requests were analyzed around that sequence.
Observed condition
Because validation and state mutation were separate operations, concurrent requests could reach the decision point before the accepted nonce was recorded. Eviction of process-local entries also weakened the intended replay boundary across time and process restarts.
Impact boundary
The condition could permit reuse of an otherwise valid signed request within the affected workflow. The practical consequence depended on the operation represented by that request and on downstream idempotency controls; it was not equivalent to forging a new signature.
Remediation direction
Nonce acceptance should be an atomic, durable operation scoped to the signer and action. Expiration, retry semantics and multi-process behavior need to be part of the same design rather than delegated to a local cache.