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My encryption subkey was explicitly _not_ generated inside the Yubikey. That was an intentional choice; I chose to sacrifice some security by generating the ke

My encryption subkey was explicitly _not_ generated inside the Yubikey. That was an intentional choice; I chose to sacrifice some security by generating the key in software and transferring it to the Yubikey, in exchange for the convenience of having the ability to do so again in the future. I made that choice because the encryption subkey is the one kind of subkey where I do not have full control over its use. What I mean is (for people still getting into this PGP stuff), with the signing and authentication subkeys, I'm the one who is performing those actions (ignoring things like compromised keys). For encryption, the sender is the one who chooses which of the encryption subkeys to use, and there is no way for me to be sure that their copy of my public key is up-to-date. (Totally off-the-rails side note: For anyone who works with Kerberos, and aliases/CNAMEs, you also have to deal with this problem, because it's the client who chooses exactly which service principal to request a ticket for.) I know that my current encryption subkey isn't going to last forever, but I wanted to be able to use it on multiple "cards" (or in this case, a Yubikey).

hdhzy 9y ago
For reference for other people this is called Key Escrow [0]. [0]: https://en.wikipedia.org/wiki/Key_escrow https://en.wikipedia.org/wiki/Key_escrow
- CaliforniaKarl 9y ago
  I don't think it is exactly key escrow, because there is no third-party involved. I generated my own keys for my own use, and nobody has access to them (that I know of). I know this might just be a semantic argument, but the Wikipedia article linked is a good example of how controversial proper key escrow (involving a third party) is. If I'd refer people to a Wikipedia article, the article on Key Management (https://en.wikipedia.org/wiki/Key_management https://en.wikipedia.org/wiki/Key_management) might be a better one, as it is more general, and my blog post touches on many key management topics.
jlgaddis 9y ago
> My encryption subkey was explicitly _not_ generated inside the Yubikey. I figured that was the reason. I use an offline master key and have separate [S,E,A] subkeys on my YubiKeys as well, although I generated them on a machine that is fairly well hardened and offline anyways -- mostly because I didn't want to risk losing them but also because I have multiple YubiKeys that I wanted to use them on.

hdhzy 9y ago

For reference for other people this is called Key Escrow [0]. [0]: https://en.wikipedia.org/wiki/Key_escrow https://en.wikipedia.org/wiki/Key_escrow

CaliforniaKarl 9y ago
I don't think it is exactly key escrow, because there is no third-party involved. I generated my own keys for my own use, and nobody has access to them (that I know of). I know this might just be a semantic argument, but the Wikipedia article linked is a good example of how controversial proper key escrow (involving a third party) is. If I'd refer people to a Wikipedia article, the article on Key Management (https://en.wikipedia.org/wiki/Key_management https://en.wikipedia.org/wiki/Key_management) might be a better one, as it is more general, and my blog post touches on many key management topics.

jlgaddis 9y ago

> My encryption subkey was explicitly _not_ generated inside the Yubikey. I figured that was the reason. I use an offline master key and have separate [S,E,A] subkeys on my YubiKeys as well, although I generated them on a machine that is fairly well hardened and offline anyways -- mostly because I didn't want to risk losing them but also because I have multiple YubiKeys that I wanted to use them on.