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? ...