Struct AuditKey 

pub struct AuditKey { /* private fields */ }

Loaded Ed25519 signing key + its identifier. Construct via AuditKey::load_or_generate.

Clone is intentional: the audit-verify CLI needs to load the key once and share it between the SQLite read-only path and the Postgres pool.

Debug is implemented manually to redact the signing key. A derived Debug would dump the private key via any tracing::debug!("{key:?}") or dbg!(key) site, which would leak the audit secret into journald. We keep key_id visible because operators need to identify which key generation a record belongs to when triaging chain breaks.

Implementations

impl AuditKey

pub fn load_or_generate(path: &Path) -> Result<Self, AuditKeyError>

Load the audit key from path. If the file does not exist, generate a 32-byte cryptographically random key and write it with mode 0o600.

On every load (including freshly generated), the file’s permissions are checked: any bit beyond 0o600 for owner-only access is rejected — a world-readable audit key is a self-defeating audit chain.

pub fn key_id(&self) -> &str

Stable identifier for this key generation.

pub fn request_hash_key(&self) -> RequestHashKey

Derive the RequestHashKey that keys request_hash (#268).

HKDF-SHA256 over the signing seed with the request-hash domain tag as info and no salt: the derived key is cryptographically separate from the Ed25519 scalar, so holding one says nothing about the other, and the domain tag keeps this derivation from aliasing any other use of the same key material.

pub fn chain_hash( &self, content: &ChainContent<'_>, prev_chain_hash: &str, ) -> String

Compute the chain signature for content linked to prev_chain_hash.

Hex-encoded Ed25519 signature over canonical(content) || prev_chain_hash. Deterministic (RFC 8032): identical inputs always yield the same value.

pub fn verifying_key(&self) -> VerifyingKey

The public verifying key for this audit key.

pub fn verifying_key_hex(&self) -> String

Hex-encoded 32-byte Ed25519 public key. Safe to publish; auditors use it to verify the chain without the ability to forge entries.

pub fn approval_receipt( &self, transaction_id: &str, request_hash: &str, ) -> String

Derive the bearer receipt for one immutable preview. The signature is deterministic, so a failed response delivery can be retried without storing plaintext bearer credentials in the database.

pub fn approval_commitment( &self, transaction_id: &str, request_hash: &str, ) -> String

Chain-stored SHA-256 commitment to the deterministic approval receipt.

impl AuditKey

pub fn event_hash( &self, content: &EventContent<'_>, prev_chain_hash: &str, ) -> String

Compute the event-chain signature for content linked to prev_chain_hash. Separate domain tag from rows and checkpoints, so an event signature can never be replayed as a transaction row.

impl AuditKey

pub fn sign_checkpoint( &self, seq: u64, chain_tip: &str, created_at: &str, ) -> Checkpoint

Sign a checkpoint committing to (seq, chain_tip) at created_at.

Trait Implementations

impl Clone for AuditKey

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for AuditKey

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.