Gemini Custody™ has institutional-grade security with 24/7 access-controlled secured facilities. The hardware security modules that store the keys (what you need to access the coins) are kept entirely offline. Gemini’s hardware security modules have achieved the highest levels of the U.S. government’s security rating.
In order to protect our clients’ crypto-assets, we have also instituted internal controls that restrict the ability for any assets to move between unauthorized accounts or parties. Specifically, any withdrawals or asset movement require real-time multi-signature authentication, two-factor authentications, and time-limited approvals.
You can read more about Gemini's security procedures here!