OneKey founder Yishi outlined what he sees as the minimum security requirements for turning an iPhone into a cryptocurrency cold wallet. In his post on Oct. 14, he said keeping a device offline alone is not enough to defend against physical extraction by forensic tools. He argued that the baseline should be an iPhone 17 or newer running iOS 27 or later, with the device replaced every one to two years.
Yishi said the A19 chip’s Memory Integrity Enforcement, or MIE, improves resistance to vulnerabilities. He also pointed to the security difference between BFU, or Before First Unlock after shutdown, and AFU, or After First Unlock, saying BFU is safer. Based on that, he advised users storing crypto offline to fully power down the device rather than simply disconnect it from the internet.
He also warned against storing seed phrases in Notes or Photos and said users should set a strong random password of at least 12 characters. For long-term storage of large holdings, he still recommended using a separate dedicated hardware signing device first.
BlockBeats reported on Oct. 14 that OneKey founder Yishi discussed how an iPhone could be turned into a cryptocurrency cold wallet.
Yishi said an offline device by itself is not enough to defend against the risk of physical extraction by forensic tools. In his view, the minimum security threshold should be an iPhone 17 or newer running iOS 27 or later, and the device should be migrated every one to two years.
Minimum security threshold and device state
Yishi said the A19 chip introduces Memory Integrity Enforcement, or MIE, which can improve resistance to vulnerabilities. He added that a device in the BFU state, meaning Before First Unlock after shutdown, is safer than the AFU state, or After First Unlock.
On that basis, he said an iPhone used for offline storage should be fully powered off rather than simply kept disconnected.
Seed phrase and password guidance
He also said users should not keep seed phrases in Notes or Photos and should use a strong random password with at least 12 characters.
For long-term storage of large crypto holdings, Yishi said he still recommends a separate dedicated hardware signing device as the first choice.
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