What if the strongest way to protect your Bitcoin is not by adding features, but by removing them? That idea challenges the early hardware-wallet mindset. Back then, the belief was simple: the more cryptocurrencies a device supported, the better it was. More coins meant more capability. This belief shifted in 2020 when security researchers, including Monokh, revealed a category of flaws known as cryptocurrency isolation bypass. Their work showed that when a hardware wallet supports Bitcoin and its forks at the same time, the isolation between these assets can fail. When that happens, attackers may find a way to mis-sign transactions, and Bitcoin becomes vulnerable. Keystone created its BTC-Only firmware in response to this issue. It was designed to solve a real security weakness rather than create a marketing angle. How Removing Other Coins Can Increase Security? Imagine this scenario: - Your wallet software is compromised. - You think you are sending Litecoin. - The screen shows a Litecoin address, Litecoin amount, and Litecoin fee. Everything will appear correct. However, Bitcoin and many of its forks share the same signature format. This allows malicious software to silently replace your intended Litecoin transaction with a Bitcoin one. The hardware wallet is unable to distinguish the difference and signs the Bitcoin transaction while displaying Litecoin information. You believe you moved Litecoin. But you actually lost Bitcoin. This violates the central rule of hardware wallets: what you see should be what you sign. Why Multi-Coin Support Can Be Risky for Bitcoin Users? If you hold only Bitcoin for the long term, adding unnecessary features introduces unnecessary risk. A multi-coin firmware brings several disadvantages: 1. More code. A bigger codebase is harder to audit and easier for bugs to hide in. 2. More entry points. Each additional cryptocurrency implementation becomes another attack surface. 3. More updates. Frequent firmware updates increase the window during which supply-chain attacks may occur. Security often improves when complexity is removed. A Bitcoin-only firmware reduces the surface area where things can go wrong. What the Bitcoin-Only Firmware Still Provides? Removing altcoins does not mean removing capability. The BTC-Only firmware still covers everything serious Bitcoin users need. It supports all major address types: > Legacy > SegWit > Taproot It provides advanced protection setups: > Passphrase wallets > Shamir Backup (split mnemonics) It handles multi-signature workflows properly. The device parses and displays multi-sig details clearly, so users do not have to rely on blind signing. It remains fully open source. Anyone can inspect the firmware and verify how it works. It uses a QR-based air-gapped design. There are no physical communication channels like USB or Bluetooth. Every transaction is reviewed on a large screen before signing. A Focused Approach in a Crowded Crypto World The crypto industry often rewards devices that support thousands of assets. Keystone’s BTC-Only firmware takes a different approach: It focuses on one thing and avoids anything that could weaken it. Instead of building complexity, it removes it. Instead of offering everything, it chooses clarity. Instead of spreading attention, it strengthens a single mission. Its purpose is simple: protect your Bitcoin with as little exposure as possible.