> For the complete documentation index, see [llms.txt](https://docs.hyphen.at/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.hyphen.at/concepts/hyphen-multi-sig-account/device-key.md).

# Device Key

The device key is stored safely in the mobile device’s special secure hardware chip: **HSM (Hardware Security Module)**. Examples of HSMs are Apple's Secure Enclave (Apple T2 chip) and Android Keystore.

The key is isolated from the mobile OS using a specialized hardware chip to protect it from any security threats, and an app can only request to sign/verify a transaction- meaning that the keys stored in HSM cannot be taken out of the hardware. Therefore, It can be seen as utilizing users’ mobile devices as a cold wallet. 


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