I don't even know if common linux distributions even support the right combination of drivers and gnupg to even support 4096-bit RSA keys. I tried this a couple of times over the last two years or so, and there was always some bug, or it was fixed in a later version not in the repos yet.
I'm on OSX, and macports gpg does 4096 fine (gpg (GnuPG) 1.4.13). Also works fine on Ubuntu (gpg (GnuPG) 1.4.11)
What no one seems to support is ECC, but until I get more confirmation, I'm inclined to follow Schneier and stick to 4096 RSA in preference to ECC, at least where possible.
I really don't want my key to be on my general-purpose machine. I have fully airgapped machines for code signing and such, but for regular communications, I want a key which can be used from my laptops (mac, ubuntu) and ideally from iOS/Android (via bluetooth), without being exposed to compromise on the host. You can force me to sign or decrypt arbitrary stuff while my key is paired, but can't steal my key.
Ideally v2 would have some kind of log of all transactions on the secure token, so I can at least see if I'm being trolled for signatures/decrypts by malware on the host, and in v3, some kind of secure UI on the device.
I figure I could make a device like this, in a fully open/auditable design, for <$250/unit. Ideally something which looks like the Blackberry CAC reader, but uses bt 4.0 le to talk to a paired host, rather than power-hungry bluetooth.
The bug in question was the interaction between the GPF cryptostick and 4096-bit RSA keys. You could create them, put them on the stick, but trying to verify signatures had a bug. I believe it's fixed
I can confirm the German Privacy Foundation PGP stick does NOT support ECC.
You might talk to the GPF, they are currently working on their next version of their cryptostick, and it's supposed to have encrypted USB storage and the ability to support applets.
