Using an old iPhone as a crypto cold wallet may be less safe than it looks, OneKey founder Yishi Wang has warned. The practice is popular with self-custody fans: wipe a spare phone, take it offline, and keep your wallet recovery information on it.
iPhone Isn't Unbreakable
Wang's worry is that an offline phone can still be attacked by someone who has it in their hands. He has pointed to flaws in several generations of iPhone. These include the publicly documented checkm8 issue on older models and, more recently reported, low-level weaknesses in certain later devices. They sit in the early stages of the boot process. A malicious app isn't involved.
An iOS update may not fix a weakness built into immutable boot code. Switching off Wi-Fi and cellular does nothing about someone who gets physical access to the phone. A vulnerability still doesn't automatically mean an attacker can recover a seed phrase, though. Device encryption, passcode strength and secure key handling remain real barriers.
Wang advises against trusting iPhone 11-generation and older devices with recovery phrases. If you think a phrase may have been exposed, create a completely new one using a trusted setup and move your funds to that wallet. Generating another address from the same seed won't help, because the underlying exposure stays.
Avoiding attack vectors
He also stresses updated operating systems, long alphanumeric passcodes and careful control of USB connections. Earlier, he suggested that even newer iPhones shouldn't be treated as equivalent to purpose-built signing devices when the holdings are substantial and long-term.
Dedicated hardware wallets are built to isolate signing keys and let you check transaction details on the device itself. They carry risk too. Counterfeit hardware, compromised distribution channels and sloppy recovery-phrase handling can all undermine their security.
The argument is about threat models, not brand loyalty. An offline phone cuts remote exposure, but that doesn't turn it into a secure hardware wallet.