Module crypt 

Crypt zone keys and per-member wraps (ADR-038, Crypt.md).

Each Crypt zone has one random AES-256-GCM key. Per-member access is granted by wrapping that key under a KEK derived from a pairwise X25519 ECDH between the granter’s identity and the recipient’s identity (ADR-038, JOY-0157-86). Going through identity material that is stable across passphrase rotation (ADR-039) means passphrase changes do not invalidate Crypt access.

Wrap format on disk: hex-encoded granter_verify_key (32 bytes) || nonce (12) || ciphertext || tag (16).

Self-wrap (auto-create on joy crypt add) is the special case where granter and recipient are the same member; the wrap format is identical so the unwrap path is uniform.

Structs

ZoneKey

32-byte AES-256-GCM key for a Crypt zone.

Constants

DEFAULT_ZONE

Conventional name of the implicit default zone.

FILTER_MAGIC

Magic prefix for Crypt-encrypted file blobs (Git filter format).

FILTER_VERSION

On-disk blob format version. Bump on incompatible changes.

Functions

active_zone_key

Look up an active zone key. Used by joy-core’s read path when decrypting a JOYCRYPT blob.

clear_active_zone_keys

Wipe the thread-local active zone-keys. Call at the end of a command to ensure no plaintext key material outlives the process (Drop in main.rs covers normal exit).

decrypt_blob

Inverse of encrypt_blob. Returns (zone_name, plaintext).

encrypt_blob

Encrypt content for a zone in the Git-filter blob format (JOY-014B-09):

has_active_zone_keys

Whether any zone key is currently active. Useful for joy-cli to decide whether to prompt for passphrase before reading items.

looks_like_blob

Quick check for whether a byte slice begins with the Crypt blob magic. Read paths use this to short-circuit when content is already plaintext (item not encrypted, or file outside any zone).

set_active_zone_keys

Replace the thread-local active zone-keys with the given map. Typically called once per joy command after passphrase verification.

unwrap_for_member

Unwrap a zone key. Reads the granter’s verify_key from the wrap header, derives the same pairwise KEK on the recipient side, and decrypts the inner blob.

wrap_for_member

Wrap a zone key for a recipient. The granter contributes their X25519 secret (derived from their identity seed); the recipient is addressed by their Ed25519 verify_key. Self-wrap is a special case where granter and recipient identify the same member.

wrap_for_self

Convenience wrapper: self-wrap produced by a member for themselves.