The Kerckhoffs Chamber

Six rooms on the third floor, all double-aspect, all looking out over the lindens on Ritterstraße. The plan is classic: bed on the wall opposite the window, a low oak credenza, a small upholstered armchair, and a deep writing desk built into the window bay with two outlets, a USB-C charger, and one of those small brass lamps you reach for without looking.

The door has a real mortice lock and a real key on a real brass fob — engraved with the room number and the words Auguste Kerckhoffs · 1883. We replace lost keys for €25. We have replaced fewer than you'd think.

Materials

• Bauwerk lime plaster walls (Bone Nº 02 with Moss Nº 07 picture rail)
• Smoked oak flooring with a hand-knotted Marrakesh rug
• Bath: Carrara marble vanity, Vola brass fittings, Le Labo Bergamote 22 amenities

Technology

• Wi-Fi 6 (Ubiquiti U6 Pro), guest VLAN by default
• Wired 1 Gbps drop at the desk
• Genelec 4030C speakers, Bluetooth 5.3
• Television: 55" OLED behind a smoked-oak panel

On the name

The cipher must not be required to be secret, and must be able to fall into the hands of the enemy without inconvenience. — Auguste Kerckhoffs, La cryptographie militaire, 1883

A century and a half later we still build systems on this principle, and it is still the second-best thing a guest of this hotel can lose sleep over. (The first is whether the breakfast pastries hold out past 09:30 on Sundays. They do not.)