Goblin

Goblin is a private, Cash App-style wallet for GRIN ツ — confidential digital cash on Mimblewimble, with no amounts or addresses on the chain.

Instead of passing slatepack files back and forth, you pay a @username (or an npub) and the payment is delivered for you as an end-to-end encrypted message over nostr, routed through the Nym mixnet. Relays only ever see ciphertext — never the amount, the sender, or the recipient — and the mixnet hides who is talking to whom at the network layer.

Goblin is a fork of the Grim egui GRIN wallet: it keeps Grim's full GRIN node/wallet engine and layers a Nostr-native, mobile-first payments experience on top.

What it does

• Send to people — pay a @username or npub; the GRIN slatepack travels as a NIP-17 gift-wrapped DM (kind 1059) over the Nym mixnet and is applied automatically by the recipient's wallet. No files to swap, no need to both be online at once.
• In-app identity — a nostr payment key that is deliberately not part of your seed, so you can rotate it any time to stay unlinkable without touching your funds. An optional human-readable @name (and hosted avatar) comes from the goblin.st identity service.
• Private by construction — GRIN's address-less, confidential chain; every relay and HTTP request (relays, NIP-05 lookups, price, avatars) routed through the Nym mixnet via a bundled nym-socks5-client sidecar, so nothing touches the clear net; keys, names and history stay on your device.
• Configurable amount pairing — show balances against a world currency, Bitcoin, or sats (rates fetched over the mixnet), or turn the preview off.
• Cross-platform — Linux, macOS, Windows, Android, built in pure Rust on egui.

How a payment travels

   you ──slatepack──▶ NIP-17 gift wrap (kind 1059, NIP-44 encrypted)
                          │
                   Nym mixnet (5-hop)
                          │
            ┌─────────────┴─────────────┐
        your relays              recipient's DM relays (kind 10050)
            └─────────────┬─────────────┘
                          ▼
   recipient ◀──unwrap, verify seal author, apply slatepack

The wrap is NIP-44-encrypted, and delivery uses the recipient's DM relay list (kind 10050).

Both parties only need one relay in common. The default set is the Goblin relay plus large public relays (relay.damus.io, nos.lol), and the set is editable in Settings → Relays.

Build

Desktop (Linux / macOS / Windows)

git submodule update --init --recursive
cargo build --release
./target/release/goblin

Goblin routes all of its traffic over the Nym mixnet using a nym-socks5-client sidecar that runs alongside the wallet and exposes a local SOCKS5 proxy on 127.0.0.1:1080. Ship the nym-socks5-client binary next to the goblin executable (or point GOBLIN_NYM_BIN at it), and set the network requester it routes through via GOBLIN_NYM_PROVIDER (or bake it into NETWORK_REQUESTER in src/nym/sidecar.rs). If a SOCKS5 endpoint is already listening on 127.0.0.1:1080, Goblin reuses it.

Android

Install the Android SDK / NDK, then from the repo root:

./scripts/android.sh build|release v7|v8|x86

v7/v8/x86 is the device CPU architecture for build; for release pass a version in major.minor.patch form.

Identity service (goblin-nip05d)

The optional @name + avatar service lives in goblin-nip05d/ (axum + SQLite) and is deployed at goblin.st. It implements NIP-05 resolution, NIP-98-authenticated registration/transfer/release, and a hardened avatar pipeline (magic-byte sniffing, bounded decode, full re-encode to a clean 256×256 PNG). The wallet is fully usable — and fully anonymous — without it.

License

Apache License v2.0.

Credits

🤖 Built with AI pair-programming assistance (Claude)

The underlying cross-platform GRIN wallet engine is the upstream Grim project.