Tin Hat Linux - Design Goal

Design Goal

The central design consideration in Tin Hat is to construct an operating system that can hide data from an attacker even if he has physical access to the computer. Physical access to a computer with unencrypted filesystems does not secure the data and an attacker could easily retrieve the data. Encrypting the filesystem provides protection from such an attack, but many implementations of encryption do not hide the fact that data is encrypted on the filesystem. For example, the LUKS encryption system includes metadata which detail the block cipher and block cipher mode used in encryption. This information does not help the attacker decrypt the filesystem, but it does reveal that it contains encrypted data and not random data. However, Tin Hat stores its filesystem in the RAM, leaving no data in the computer's hard drive. If the user stores any data via a more permanent means than RAM, the encrypted data is indiscernable from random data.

Tin Hat's preferred method of encryption is via loop-aes v3.

Beyond these considerations, Tin Hat has to also protect against more common exploits based on networking or security holes in software. The hardening model chosen is PaX/Grsecurity which is already provided by the Hardened Gentoo project. Hardening of the kernel and the toolchain make most code born exploits less likely. A non-modular compiled kernel further frustrates the insertion of malicious kernel modules.