dig-session

The DIG session / keystore layer: a small, custody-safe facade that turns stored, encrypted key material into a live signer and injects a bare signing primitive into downstream consumers.

It composes two lower-level crates and adds no cryptography of its own:

• dig-keystore — encrypted, per-scheme secret-key storage (Keystore::<K>::load -> unlock -> SignerHandle).
• dig-identity — the canonical DIG BLS identity derivation (m/12381'/8444'/9'/0').

Install

[dependencies]
dig-session = "0.1"

Use

use std::sync::Arc;
use dig_session::{Session, FileBackend, BackendKey, Password};

# fn main() -> dig_session::Result<()> {
let backend = Arc::new(FileBackend::new("/var/lib/dig/keys"));

// Enroll a new identity from BIP-39 seed bytes (derives the canonical
// dig-identity signing key and stores it encrypted).
let identity = Session::enroll_identity(
    backend.clone(),
    BackendKey::new("identity"),
    Password::from("correct horse battery staple"),
    b"seed bytes",
)?;

// Sign directly...
let _sig = identity.sign(b"message");

// ...or hand a downstream a bare signing primitive — it never sees a session type.
let sign = identity.signing_fn();
let _sig = sign(b"message");

// Reopen later.
let identity = Session::unlock::<dig_session::L1WalletBls>(
    backend,
    BackendKey::new("identity"),
    Password::from("correct horse battery staple"),
)?;
# let _ = identity;
# Ok(())
# }

Design notes

• No seal / decap. Recipient message encryption belongs to dig-message, not here.
• Identity keys are stored with L1WalletBls, not BlsSigning. The identity key is already derived by dig-identity; storage must round-trip it via from_bytes. BlsSigning would re-derive via from_seed and yield a different key (the dig_ecosystem #64/#57 pitfall).
• Custody-safe. UnlockedIdentity zeroizes its secret on drop, never Debug-prints key material, and must never cross an IPC boundary.

See SPEC.md for the normative contract.

License

GPL-2.0-only.