[nickpsecurity]

Most of them use risky web tech, insecure endpoints, hosting (always risky), or developers/servers under risk of coercion by major nation-states in surveillance game. All untrustworthy. My main post above outlines what it takes to make a strong assurance argument and let's just say there's few that can do it. Their time is also expensive.

My temporary solution is to combine endpoint encryption (eg GPG), MyKolab for address/storage, air gaps, and a guard. The MyKolab account gets me Swiss storage with associated legal protection & lack of clever Google-style snooping. I assume the servers are compromised along with messages. To deal with those threats, people send me either GPG messages or otherwise encrypted files. For protection, I can download them to a disposable, hardened PC; send them through a guard or data diode for reading; use a separate computer for writing and signing with a data diode. This is Markus Ottela's architecture for Tinfoil Chat. His diodes with separate PC's are simpler than my guards with KVM-connected PC's. So I recommend it his way these days.

You can swap out MyKolab for any other service for delivery or storage. You just have to make sure they're totally untrusted, incoming messages can't compromise your keys, and keys/secrets can't leak out. Tricky stuff for any of these developers. TFC already does this. I suggest these people modify its latest incarnation to do email (maybe apply GPG), find any other flaws it has, and improve on docs/distribution. Will get more mileage.

[walterbell]

> a disposable, hardened PC

Do you mean a PC booted with a non-persistent OS like Tails or a Linux Live CD?

How would you rate a Qubes VM for this purpose?

[nickpsecurity]

Security-oriented Live CD's or virtualization tech can be used for any of these except the links between systems (eg guard, diodes). QubesOS lowers its attack surface by using Xen instead of a full Linux distro, albeit with risk in Dom0 & hardware attacks. That they isolate their firewall and such is a good thing. Linux or FreeBSD, more mature but larger attack surface, should include full usage of any hardening guides, software protections (eg Softbound, Control Pointer Integrity), mandatory access controls (eg SELinux, SMACK), device protection (eg IOMMU or PIO interface), and so on. Whatever the most paranoid people use basically and do this in any applicable parts of QubesOS as well.

You just want these systems hardened from attack as much as possible along with ease of detection and easy recovery. The disposable part means exactly what it says: the Internet-connected computer is the target and filter of the most risky functionality. It will be toast at some point, maybe often. So, use a throwaway device for it.