Glossary¶

Technical terms used throughout the Mycel documentation. User-level terms are marked with (User).

A¶

ACK (Acknowledgment)¶

Confirmation that a message was delivered. See DeliveryAck.

AES-256-GCM¶

Symmetric encryption algorithm used for group messages and DM content encryption.

B¶

Bundle¶

Self-contained message unit in DTN. Contains header (routing metadata) and payload (encrypted content). Think of it as a sealed envelope with address labels. See Bundle Structure.

Bundle Status¶

Lifecycle state of a bundle: NEW, RECEIVED, RECEIVED_FORWARDABLE, FWD, DEL, EXP, ERR, CANCELLED. See Bundle Lifecycle.

C¶

CBOR¶

Concise Binary Object Representation. Binary serialization format used for bundles and control messages.

Control Message¶

System message for routing, subscriptions, and network coordination. Types 1-12. See Message Types.

Copy Budget¶

Spray-and-Wait parameter limiting message replication. Decrements on each forward.

CRDT¶

Conflict-free Replicated Data Type. Used for group membership synchronization. See Private Groups.

D¶

DeliveryAck¶

Signed end-to-end acknowledgment from recipient (msgType=8). Primary ACK mechanism.

DeviceId¶

Ed25519 public key identifying a device. 32 bytes.

DRAIN¶

Session state: connected, transfer-ready, queues empty, idle.

Delivery (User)¶

When your message reaches its intended recipient. In Mycel, this can take seconds (nearby) or days (multi-hop across the mesh).

DTN¶

Delay-Tolerant Networking. Architecture for communication without continuous connectivity. The key insight: embrace delays rather than require always-on connections.

E¶

ECIES¶

Elliptic Curve Integrated Encryption Scheme. Used for DM encryption: X25519 ECDH + HKDF + AES-256-GCM.

Ed25519¶

Elliptic curve signature algorithm. Used for device identity and message signing.

F¶

Forward (FWD)¶

Bundle status indicating active forwarding in progress.

G¶

Gift-Wrap¶

NIP-17 Nostr encryption that hides sender/recipient from relays. Double encryption with random author.

Group Key¶

32-byte AES-256 symmetric key shared by all group members.

GroupInviteMsg¶

Control message (msgType=6) for encrypted group invitations.

H¶

H3¶

Uber's hexagonal hierarchical spatial index. Used for geographic routing.

HKDF¶

HMAC-based Key Derivation Function. Derives AES key from ECDH shared secret.

HopAck¶

Control message (msgType=2) confirming custody transfer at each hop.

I¶

Interest Filter¶

Bloom filter containing topics a device is interested in. Used for routing.

IDLE¶

Session state: disconnected, no active connection.

L¶

L2CAP¶

Bluetooth Logical Link Control and Adaptation Protocol. Used for BLE data transfer.

M¶

Mesh (User)¶

The network of Mycel devices that relay messages for each other. Everyone running Mycel is part of the mesh. More people = better coverage = faster delivery.

MeshService¶

Android foreground service managing DTN operations.

MycTag¶

Human-readable identity string. Format: myc:<10-char-base32>.

MycTagStar¶

Cluster identity derived from member public keys.

N¶

Nearby Connections¶

Google Play Services API for local device discovery and communication via BLE/WiFi.

NIP¶

Nostr Implementation Possibility. Protocol extension for Nostr.

NIP-17¶

Gift-wrap encryption for private DMs on Nostr relays.

NIP-44¶

Versioned encryption for Nostr event content.

Nostr¶

Protocol for decentralized communication via relay servers.

P¶

P-value¶

PRoPHET delivery predictability probability (0.0-1.0).

PRoPHET¶

Probabilistic Routing Protocol using History of Encounters and Transitivity. See PRoPHET Algorithm.

R¶

Relay (User)¶

Any device that carries your message toward its destination. Every Mycel user's phone acts as a relay for other people's messages. You help others; they help you.

Relay (Nostr)¶

WebSocket server that stores and forwards Nostr events.

Route Path¶

List of clusters a bundle has traversed. Max 8 hops.

S¶

Session State¶

Connection lifecycle state: IDLE, DISCOVERY, CONNECTING, SESSION_OPEN, SYNC, XFER, DRAIN, CLOSING. See Nearby Transport.

Spray-and-Wait¶

Routing algorithm limiting message copies to prevent flooding.

Store-and-Forward¶

DTN principle where nodes store messages locally until forwarding opportunity.

T¶

Topic¶

Identifier for group or channel. 32-byte hash used for interest-based routing.

TTL¶

Time-to-Live. Duration after which a bundle expires.

Transport¶

Physical delivery mechanism: Nearby Connections or Nostr.

U¶

UID¶

User ID. SHA256 hash of device public key. 32 bytes.

W¶

Watchdog¶

Background process monitoring Nearby connection health.

X¶

X25519¶

Elliptic curve Diffie-Hellman for key exchange. Derived from Ed25519 keys.

XFER¶

Session state: connected, actively transferring data.

XChaCha20-Poly1305¶

Authenticated encryption used for group invites. 24-byte nonce variant.

Quick Reference¶

Term	Size	Algorithm
Device Key	32 bytes	Ed25519 public
Private Key	64 bytes	Ed25519 (seed + public)
UID	32 bytes	SHA256(pubKey)
MycTag	10 chars	base32(UID[:6])
Bundle ID	32 bytes	SHA256(header + payload)
Signature	64 bytes	Ed25519
Group Key	32 bytes	AES-256
Nonce (GCM)	12 bytes	Random
Nonce (XChaCha)	24 bytes	Random

See also: Index | Architecture