Nulla — Bitcoin Light Wallet

A minimalist Bitcoin light client built in the spirit of Electrum. No full node required. Connects directly to the Bitcoin network via ElectrumX servers.

Standalone app — future integration with LightAnonChain (LAC) for BTC↔LAC atomic swaps.

Features

• BIP39 — 24-word mnemonic (256-bit entropy)
• BIP84 — Native SegWit addresses (bc1q…)
• BIP44 — Legacy addresses (1…)
• ElectrumX — connects to Bitcoin network without running a full node
• UTXO management — coin selection, fee estimation, change addresses
• BIP143 — correct sighash for SegWit transactions
• Encrypted keystore — AES-256-GCM + PBKDF2 × 600k iterations + HMAC-SHA256
• CLI + Web UI — both interfaces included
• Testnet support — --testnet flag

Architecture

nulla_core.py       BIP39/32/44/84 HD wallet, bech32, keystore
nulla_electrum.py   ElectrumX protocol client (SSL/TCP, JSON-RPC)
nulla_tx.py         Bitcoin transaction builder (P2WPKH + P2PKH, BIP143)
nulla_cli.py        Command-line interface
nulla_server.py     Flask JSON API + React SPA
ui/                 React frontend (dark theme, Bitcoin orange)

Quick Start

git clone https://github.com/epidemiaya/nulla
cd nulla

python -m venv .venv

# Windows
.venv\Scripts\activate
# macOS / Linux
source .venv/bin/activate

pip install -r requirements.txt

# Build UI
cd ui
npm install
npm run build
cd ..

# Start (opens browser automatically)
python nulla_server.py

Open: http://localhost:7421

---

CLI Usage

python nulla_cli.py create              # Create new wallet
python nulla_cli.py import word1 ...    # Restore from mnemonic
python nulla_cli.py balance             # Show balance
python nulla_cli.py receive             # Show receive address
python nulla_cli.py send bc1q... 0.001  # Send BTC
python nulla_cli.py utxos               # List UTXOs
python nulla_cli.py history             # Transaction history
python nulla_cli.py fee                 # Current fee estimates
python nulla_cli.py node                # ElectrumX server status
python nulla_cli.py accounts            # All derived addresses

# Testnet
python nulla_cli.py --testnet balance
python nulla_server.py --testnet

---

ElectrumX Servers (Mainnet)

Nulla automatically selects the fastest available server:

• electrum.blockstream.info:700
• electrum.bitaroo.net:50002
• fortress.qtornado.com:443
• electrum.jochen-hoenicke.de:50006
• bitcoin.aranguren.org:50002

---

Security

Component	Detail
secp256k1	coincurve bindings (same library as Bitcoin Core)
Signing	Deterministic ECDSA (RFC6979), low-S enforced (BIP62)
Keystore	AES-256-GCM, PBKDF2-SHA256 × 600,000 iterations
MAC	HMAC-SHA256 verified before decryption (constant-time)
Server	Binds to 127.0.0.1 only — never exposed to network
Memory	wallet.lock() wipes key material from RAM

---

Roadmap

• BIP39 / BIP84 / BIP44 HD wallet
• ElectrumX protocol client
• P2WPKH transaction building & signing
• CLI + Web UI
• P2SH-SegWit (BIP49) support
• Hardware wallet (Trezor / Ledger)
• BTC↔LAC atomic swap module

---

License

MIT — part of the LightAnonChain ecosystem.