Pure Rust · Live on Solana Mainnet

Air-gapped cold signing
written in pure Rust

Your private key lives encrypted on a $10 USB drive. When you sign, it's decrypted in mlock'd RAM for ~100 microseconds, then zeroized. No GC, no FFI, no Python runtime. 12 crates, 228 tests, 18,380 lines of auditable Rust.

View on GitHub Install Now crates.io

                $
                cargo install coldstar

Crates

228

Tests

18,380

Lines of Rust

Unsafe Blocks

How It Works

Three steps. No special hardware required.

1

Encrypt keys to USB

Create a wallet or import an existing one. Your private key is encrypted with AES-256-GCM + Argon2id KDF, then saved to any USB drive.

2

Sign in mlock'd RAM

When you send a transaction, the key is decrypted in mlock'd memory for ~100 microseconds to sign, then zeroized. No GC means no copies linger.

3

Broadcast

Only the ed25519 signature (public data) is sent to the Solana network. Your private key never touched the internet, never touched disk.

Install Coldstar

Three ways to get started. Pick your favorite.

terminal

# From crates.io (recommended)
cargo install coldstar

# From Homebrew
brew tap ExpertVagabond/coldstar-homebrew
brew install coldstar

# From source
git clone https://github.com/ExpertVagabond/coldstar-rs
cd coldstar-rs && cargo build --release

Requires Rust 1.75+ (or Homebrew on macOS/Linux). Cross-platform: macOS, Linux, Windows. For air-gapped mode, see full docs.

coldstar output

COLDSTAR v2.0 — Pure Rust Air-Gapped Cold Wallet

[+] USB detected: KINGSTON 32GB (/dev/disk4s1)
[+] Wallet loaded: 7xKp...9mFv
[+] Balance: 12.847 SOL ($2,441.08)
[+] Security: mlock + zeroize active

  1. View Wallet / Balance
  2. Send SOL (Create Unsigned Transaction)
  3. Sign Transaction (Air-Gapped)
  4. Broadcast Signed Transaction
  5. Swap Tokens (Jupiter)
  6. Generate ZK Proof
  7. Backup / Restore Wallet

▸ Select an option: █

Air-Gap Architecture

Keys never leave the USB. Signatures never touch disk.

USB Drive AES-256-GCM encrypted keypair + Argon2id KDF salt ENCRYPTED AT REST

↓

mlock'd RAM Key decrypted for ~100us, ed25519 sign, immediate zeroize() NEVER SWAPPED TO DISK

↓

Signature Only 64-byte ed25519 signature broadcast to Solana RPC PUBLIC DATA ONLY

mlock()

Memory pages pinned, cannot be swapped to disk

zeroize()

Compiler-guaranteed zeroing on Drop, no dead-store elimination

No GC / No FFI

No garbage collector copies, no foreign function boundary leaks

Why Coldstar?

Pure Rust

Every line is Rust. No Python runtime, no Node.js, no GC. Deterministic memory management means your keys are never copied by a garbage collector.

18,380 LOC

mlock + zeroize

Memory-locked pages prevent swap-to-disk. Zeroize trait guarantees keys are overwritten on drop. No compiler can optimize the wipe away.

AES-256-GCM + Argon2id

$10 vs $200

Any USB drive works. No proprietary chips, no serial numbers, no vendor to trust. If a drive is compromised, destroy it and restore from backup for $5.

Cost: $0

ZK Proofs

Generate zero-knowledge proofs of wallet ownership without revealing the private key. Prove you control an address without signing a transaction.

Groth16

Cross-Platform

Compiles natively on macOS, Linux, and Windows. Single binary, no runtime dependencies. Install from crates.io, Homebrew, or build from source.

macOS + Linux + Windows

Fully Open Source

Every line is public on GitHub. 12 modular crates on crates.io. You can audit the entire security model — no hidden firmware, no trust required.

MIT License

12 Crates on crates.io

Modular architecture. Use the full CLI or integrate individual crates into your project.

★

coldstar

Main CLI binary. Air-gapped cold wallet for Solana with TUI interface.

⚙

coldstar-core

Core types, traits, and shared primitives used across all crates.

🔒

coldstar-crypto

AES-256-GCM encryption, Argon2id KDF, mlock/zeroize memory security.

👛

coldstar-wallet

Wallet creation, import, backup, and restore operations.

✎

coldstar-signer

ed25519 transaction signing in mlock'd RAM with automatic zeroize.

💾

coldstar-usb

USB drive detection, mounting, and encrypted keystore management.

🌐

coldstar-rpc

Solana RPC client for balance queries, transaction broadcast, and status.

⇄

coldstar-swap

Jupiter DEX integration for token swaps from the command line.

∅

coldstar-zk

Zero-knowledge proof generation for wallet ownership verification.

▒

coldstar-tui

Terminal user interface with ratatui for interactive wallet management.

🤖

coldstar-mcp

MCP server for AI agent wallet access. 14 tools, read-only by default.

⚙

coldstar-config

Configuration management, network selection, and RPC endpoint handling.

How It Compares

	Coldstar	Ledger	Unruggable
Language	Pure Rust (no GC, no FFI)	C / proprietary firmware	Mixed
Hardware	Any USB drive	Proprietary device	Custom hardware
Memory security	mlock + zeroize (compiler-guaranteed)	Secure element	Device-dependent
Supply chain risk	None — commodity USB, open-source code	Must trust vendor hardware + firmware	Must trust manufacturer
ZK proofs	✓ Built-in	✗	✗
Open source	✓ Fully (12 crates)	✗	✓
Price	Free + any USB	$79-149	$40-80