4 ms·

One thing is clear: this is a smartcard, the private key never leaves the token, period. gpg-agent acts only as a middleman between ssh and the token, that's al

One thing is clear: this is a smartcard, the private key never leaves the token, period. gpg-agent acts only as a middleman between ssh and the token, that's all. It's impossible to capture or extract the private key (unless you're the NSA and you have physical possession of the token, I guess). Now, are there ways to attack the authentication via tapping as root into the gpg-agent process? I don't think so, but frankly I'm not that familiar with the sausage-making parts of it. I'd like to learn more about this topic.

MichaelGG 12y ago
> impossible to capture or extract the private key They should get FIPS 140-2 Level 4 certification, then. Other devices that claimed to be so resistant haven't really fared that well when someone actually bothered to look. It might be out if there range of average software hackers, but perhaps easily handled by someone with hardware capabilities. Even the Chrysalis Luna CA3 (I think that model) was breached by a university team. And a sole researcher breached a popular TPM, finding no special protection. So I'm not sure it's justified to say it requires an NSA level adversary. The bar is probably much lower. On personal stuff, I use drive level encryption, then Bitlocker with TPM, then Athena SCS smartcard for logon+EFS, and Bitlocker on a vhd for the VM actually running stuff. Only the last layer, the passphrase on the vhd, is something I count on. The rest is just to make it easy to brick the device and prevent a quick handed adversary from quickly installing a rootkit. In particular, I have very little confidence in Crucial's SSD's drive encryption. For all I know, the key is stored unencrypted on the first sector. But it's totally free, as the device runs AES to balance the 1s and 0s anyways.
- AlyssaRowan 12y ago
  On that note, have you noticed how few Level 4s there are?
- Florin_Andrei 12y ago
  > Other devices that claimed to be so resistant haven't really fared that well when someone actually bothered to look. The popularity of these things seems to be growing pretty fast, so I'd expect someone will take a look pretty soon. A lot of these tokens, or similar models, are used by large, famous high-tech companies for their employees. That's bound to attract some school-of-hard-knocks probing from 3rd parties (beyond what the googles and the facebooks of the world did before they deployed it to their internal users).
- gcb0 12y ago
  ssh-agent would be which level? well, we will never know because there is a industry making money out of that and open source don't usually buy it. Also, no modern vendor would get anything above level 2, because that will also lock your solution to one platform. i doubt you would be praising it if you couldn't install windows 8.1 or the latest osx of the week if you had to wait 2 months for the certification process every time.
- csirac2 12y ago
  Level 4 isn't exactly a walk in the park; YubiCo have said their excuse is cost. They're listed as achieving Level 1 according to http://csrc.nist.gov/groups/STM/cmvp/documents/140-1/140val-all.htm#2267 http://csrc.nist.gov/groups/STM/cmvp/documents/140-1/140val-... But this list spans 20 years of vendor certifications, and I count only 19 entries out of 2277 which have achieved Level 4. Edit: Oops, actually only Overall Level 1. http://csrc.nist.gov/groups/STM/cmvp/documents/140-1/140sp/140sp2267.pdf http://csrc.nist.gov/groups/STM/cmvp/documents/140-1/140sp/1...
- bestham 12y ago
  The normal (non smart card version) of the Yubikey was shown beached during 30C3 last year[1]. [1]: https://www.youtube.com/watch?v=H-cpm7D8Sqg#t=1720 https://www.youtube.com/watch?v=H-cpm7D8Sqg#t=1720
mpyne 12y ago
I was about to ask how the BadUSB brouhaha affects the YubiKey, but then I just realized that (of course) my own smartcard reader is plugged in via USB, so the situation can't be that much worse.

MichaelGG 12y ago

> impossible to capture or extract the private key They should get FIPS 140-2 Level 4 certification, then. Other devices that claimed to be so resistant haven't really fared that well when someone actually bothered to look. It might be out if there range of average software hackers, but perhaps easily handled by someone with hardware capabilities. Even the Chrysalis Luna CA3 (I think that model) was breached by a university team. And a sole researcher breached a popular TPM, finding no special protection. So I'm not sure it's justified to say it requires an NSA level adversary. The bar is probably much lower. On personal stuff, I use drive level encryption, then Bitlocker with TPM, then Athena SCS smartcard for logon+EFS, and Bitlocker on a vhd for the VM actually running stuff. Only the last layer, the passphrase on the vhd, is something I count on. The rest is just to make it easy to brick the device and prevent a quick handed adversary from quickly installing a rootkit. In particular, I have very little confidence in Crucial's SSD's drive encryption. For all I know, the key is stored unencrypted on the first sector. But it's totally free, as the device runs AES to balance the 1s and 0s anyways.

AlyssaRowan 12y ago
On that note, have you noticed how few Level 4s there are?
Florin_Andrei 12y ago
> Other devices that claimed to be so resistant haven't really fared that well when someone actually bothered to look. The popularity of these things seems to be growing pretty fast, so I'd expect someone will take a look pretty soon. A lot of these tokens, or similar models, are used by large, famous high-tech companies for their employees. That's bound to attract some school-of-hard-knocks probing from 3rd parties (beyond what the googles and the facebooks of the world did before they deployed it to their internal users).
gcb0 12y ago
ssh-agent would be which level? well, we will never know because there is a industry making money out of that and open source don't usually buy it. Also, no modern vendor would get anything above level 2, because that will also lock your solution to one platform. i doubt you would be praising it if you couldn't install windows 8.1 or the latest osx of the week if you had to wait 2 months for the certification process every time.
csirac2 12y ago
Level 4 isn't exactly a walk in the park; YubiCo have said their excuse is cost. They're listed as achieving Level 1 according to http://csrc.nist.gov/groups/STM/cmvp/documents/140-1/140val-all.htm#2267 http://csrc.nist.gov/groups/STM/cmvp/documents/140-1/140val-... But this list spans 20 years of vendor certifications, and I count only 19 entries out of 2277 which have achieved Level 4. Edit: Oops, actually only Overall Level 1. http://csrc.nist.gov/groups/STM/cmvp/documents/140-1/140sp/140sp2267.pdf http://csrc.nist.gov/groups/STM/cmvp/documents/140-1/140sp/1...
bestham 12y ago
The normal (non smart card version) of the Yubikey was shown beached during 30C3 last year[1]. [1]: https://www.youtube.com/watch?v=H-cpm7D8Sqg#t=1720 https://www.youtube.com/watch?v=H-cpm7D8Sqg#t=1720

mpyne 12y ago

I was about to ask how the BadUSB brouhaha affects the YubiKey, but then I just realized that (of course) my own smartcard reader is plugged in via USB, so the situation can't be that much worse.