Streiff and Kon are taking me to see Xapo’s “private suite,” an ultra-secure, customized, portion of the data center. We pass through a second man-trap and then end up in front of a nondescript white door. “This is further than anyone outside Xapo has been,” Streiff tells me, as he unlocks it. Inside is a space about the size of a walk-in closet containing a cooling unit, and yet another door. But that’s as far as they’ll let me go, and I’m not allowed to take photographs. ... Beyond that door, I rely on what Carlos Rienzi, Xapo’s head of security, tells me later, when I’m back in London. Rienzi chose the vault for Xapo, and he designed the private suite and its security protocols. His “threat model,” as computer security jargon goes, is to protect against attacks from “well-funded terrorist groups or hackers." There are two more portals inside the suite: the first leads to an operators’ room, and the second to a “cold room.” The cold room is encircled with steel slabs to form a Faraday cage: a barrier that protects against a possible electromagnetic pulse (EMP) attack that could wipe out the data—and thus the keys to the bitcoin—stored in the room. For digital assets like bitcoin, thick walls and a secret location are not enough. A shield against invisible modes of attack like an EMP bomb must be provided for. No one, not even the operator, enters the cold room. Its door is sealed with tape—like a crime scene—to ensure it’s not tampered with.
