Struct DurableKeyMaterial 

pub struct DurableKeyMaterial {
    pub cipher: Option<Arc<dyn PayloadCipher>>,
    pub hmac_key: Option<[u8; 32]>,
    pub hwm_key: Option<(u32, [u8; 32])>,
    pub previous_hmac_key: Option<[u8; 32]>,
    pub previous_hwm_key: Option<(u32, [u8; 32])>,
    pub integrity_sealed: bool,
    pub integrity_grandfather: HashSet<ExecutionId>,
}

Key material and integrity-seal state shared by every durable-backend construction call site: open_durable_backend, the P1/P2 AgentBuilder::with_durable_* methods (builder.rs), and their reassembly points in Agent::ensure_session_durable_ctx and plan.rs’s ensure_durable_backend (#6458).

hmac_key is None for a single-user local, non-shared database (INV-8) — the documented stance where control entries carry no HMAC. hwm_key (issue #6360) is meant to be attached unconditionally (FR-009): None only when ZEPH_DURABLE_KEY itself is unavailable — unlike hmac_key, single-user local deployments still get high-water-mark deletion detection. previous_hmac_key is Some only while a zeph durable rotate-key rotation window is open (#6451). previous_hwm_key is the HWM-side counterpart, Some under the same condition (addendum to #6451): unlike previous_hmac_key, its epoch reuses the AEAD cipher’s key_id lifecycle rather than being epoch-less try-both (see HwmKeySlot/with_previous_hwm_key in zeph-durable). integrity_sealed/integrity_grandfather (issue #6449) are resolved from the vault by crate::commands::durable::load_integrity_seal in the zeph binary crate.

A mis-wired key field here — wrong key, wrong slot, or an unintended None — never results in a silent accept: every control-entry and high-water-mark verification this key material feeds fails closed, surfacing as ControlIntegrity or HighWaterMarkIntegrity rather than a silently accepted read.

Deliberately does not derive Debug: every key field holds raw key-material bytes that must never be logged or printed (see project pitfall: secret-bearing Debug derives).

Examples

use zeph_core::DurableKeyMaterial;

// A non-durable / disabled-encryption configuration: every key slot empty.
let key_material = DurableKeyMaterial {
    cipher: None,
    hmac_key: None,
    hwm_key: None,
    previous_hmac_key: None,
    previous_hwm_key: None,
    integrity_sealed: false,
    integrity_grandfather: Default::default(),
};
assert!(key_material.hmac_key.is_none());

Fields

cipher: Option<Arc<dyn PayloadCipher>>

AEAD payload cipher; None when config.encrypt_payload = false (development mode only).

hmac_key: Option<[u8; 32]>

Current control-entry HMAC key.

hwm_key: Option<(u32, [u8; 32])>

Current high-water-mark key as (epoch, key).

previous_hmac_key: Option<[u8; 32]>

Previous control-entry HMAC key, valid only during an open rotation window.

previous_hwm_key: Option<(u32, [u8; 32])>

Previous high-water-mark key as (epoch, key), valid only during an open rotation window.

integrity_sealed: bool

Whether the durable integrity seal is set.

integrity_grandfather: HashSet<ExecutionId>

Executions grandfathered in before the integrity seal was set, exempt from verification.