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Use unique SSH keys for each service (sharing a SSH key on your GitHub/Gitlab account, network router and AWS/Azure instance is a very stupid idea) I don't see

by ybroze 10y ago

Use unique SSH keys for each service (sharing a SSH key on your GitHub/Gitlab account, network router and AWS/Azure instance is a very stupid idea) I don't see how this makes sense. Assuming your private keys all live on the same machine (presumably with 0600 in /.ssh), then if your machine is stolen and your user password compromised, access to one private key is the same as access to all of them.

Tepix 10y ago
It only protects you against SSH fingerprinting done by hostile servers.
- ybroze 10y ago
  I suppose, then, it's for those who don't want to be tracked, and not a "very stupid idea" per se. But then again, if you don't trust the remote to know who you are, then why do you have an identity with them? I mean, the remote service is SUPPOSED to know who you are. That's kinda the point.
  - jjnoakes 10y ago
    I don't think so. GitHub should know I'm the user who has access to push to repos a, b, and c. AWS should know I'm the user who has access to update code or data at places d, e, and f. But neither needs to know my full identity, or about each other, at all.
    - rad_gruchalski 10y ago
      Right. What about paid service. Shall I pay with someone else's CC or ask the bank for another one just because I don't want to be tracked.
      - pavel_lishin 10y ago
        Many banks and credit card companies offer a service that lets you generate a one-time-use credit card number.
        gruez 10y ago
        But your billing address will still be the same
        jjnoakes 10y ago
        So what? Paid services necessarily require a higher level of trust (since you are handing them money) than random internet services. So we are off-topic from ssh keys and identity. If you don't want someone knowing your personal payment details (CC #, billing address), then pay in cash and use services don't deliver things to your home. And if you can't, then just don't use a service. But that's living in way too much paranoia for most of us.
acqq 10y ago
> I don't see how this makes sense. Just imagine that somebody can request from you the ssh key to just one of the services you access. Then he gets the access to all of them.
- mirashii 10y ago
  This isn't how keys in SSH works. It's not like a password being transmitted to a server. http://www.theatlantic.com/magazine/archive/2002/09/a-primer-on-public-key-encryption/302574/ http://www.theatlantic.com/magazine/archive/2002/09/a-primer...
  - acqq 10y ago
    And this is not what I'm saying: I say imagine somebody can force you to give him your private key for one asset. He will get a key for all of them, unless you've already maintained separate keys. I was actually almost involved in one of such cases, I haven't invented it out of the thin air. If you can't imagine such a scenario happening to you, you're of course lucky and you'd like to use one private key for everything. But the scenario is real.
    - vitalysh 10y ago
      I can't imagine situation where I would be forced to give up private key. And if I'm forced to give up one, I guess they can force me to give up rest of them.
      - acqq 10y ago
        The scenario is simply: you perform some action on one service and then some entity has the right (or might) to demand from you the private key with which that action was performed, but not "give us everything you have." The equivalent when the scenario is an attack, and not a legal game: some entity manages to hack your computer with which you access the service A and on which you have only the private key for A, but not your another computer with which you access the service B, with the another key. Separate keys: just your access to the service A is compromised, one key: all accesses are compromised at once.

by ybroze 10y ago

Tepix 10y ago

It only protects you against SSH fingerprinting done by hostile servers.

ybroze 10y ago
I suppose, then, it's for those who don't want to be tracked, and not a "very stupid idea" per se. But then again, if you don't trust the remote to know who you are, then why do you have an identity with them? I mean, the remote service is SUPPOSED to know who you are. That's kinda the point.
- jjnoakes 10y ago
  I don't think so. GitHub should know I'm the user who has access to push to repos a, b, and c. AWS should know I'm the user who has access to update code or data at places d, e, and f. But neither needs to know my full identity, or about each other, at all.
  - rad_gruchalski 10y ago
    Right. What about paid service. Shall I pay with someone else's CC or ask the bank for another one just because I don't want to be tracked.
    - pavel_lishin 10y ago
      Many banks and credit card companies offer a service that lets you generate a one-time-use credit card number.
      - gruez 10y ago
        But your billing address will still be the same
        jjnoakes 10y ago
        So what? Paid services necessarily require a higher level of trust (since you are handing them money) than random internet services. So we are off-topic from ssh keys and identity. If you don't want someone knowing your personal payment details (CC #, billing address), then pay in cash and use services don't deliver things to your home. And if you can't, then just don't use a service. But that's living in way too much paranoia for most of us.

acqq 10y ago

> I don't see how this makes sense. Just imagine that somebody can request from you the ssh key to just one of the services you access. Then he gets the access to all of them.

mirashii 10y ago
This isn't how keys in SSH works. It's not like a password being transmitted to a server. http://www.theatlantic.com/magazine/archive/2002/09/a-primer-on-public-key-encryption/302574/ http://www.theatlantic.com/magazine/archive/2002/09/a-primer...
- acqq 10y ago
  And this is not what I'm saying: I say imagine somebody can force you to give him your private key for one asset. He will get a key for all of them, unless you've already maintained separate keys. I was actually almost involved in one of such cases, I haven't invented it out of the thin air. If you can't imagine such a scenario happening to you, you're of course lucky and you'd like to use one private key for everything. But the scenario is real.
  - vitalysh 10y ago
    I can't imagine situation where I would be forced to give up private key. And if I'm forced to give up one, I guess they can force me to give up rest of them.
    - acqq 10y ago
      The scenario is simply: you perform some action on one service and then some entity has the right (or might) to demand from you the private key with which that action was performed, but not "give us everything you have." The equivalent when the scenario is an attack, and not a legal game: some entity manages to hack your computer with which you access the service A and on which you have only the private key for A, but not your another computer with which you access the service B, with the another key. Separate keys: just your access to the service A is compromised, one key: all accesses are compromised at once.