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We have a company Foo, we have user data all encrypted that are stored in some kind of a database.

Correct me if I am wrong, the encryption keys have to be saved in the system.

Now say the admin called bar who is the main guy managing the system who has access to everything decides to go rouge, and he uses the encryption keys and decrypts all the data.

looks impossible, but is it remotely possible to prevent Cypher keys from being stolen by an employee?

Srinath Ganesh
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    It's easy to prevent stealing the key(s) by using an HSM, but preventing _misuse_ to decrypt data is quite a bit more complicated and less likely to be done right on a continuing basis. – dave_thompson_085 Jan 09 '19 at 03:08

2 Answers2

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Answer to your title = YES

Answer to your body question = NO

as an IT Manager, I can confidently answer your question with a no. It is not possible to prevent cypher keys from being stolen by bar or anyone else who have access to the server.

The only counter measure would be storing the keys on a different server but still needs someone who should keeps an eye on and guard. (which goes in a loop)

So in a conclusion, it's a matter of trust no more - the whole thing.

Extra

  • Anyone who have access to the specified server can decrypt whatever data on it assuming that the encryption keys are stored there too. also note that a user who has access to the specified server (with unprivileged powers) can work it around using some local / shell exploits in order to get root privileges/access allowing him/her to manipulate and steal or view sensitive information / data, also can implement a backdoor for later on access.

  • It is impossible to remotely prevent such thing, because if i'm the sys admin of that server, means i have ssh access to it, means i can use an ssh tunnel to work and do the evil stuff behind the server's IP address, so nor firewalls nor anything can block me or prevent me from stealing whatever i want.

Viktova
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@Viktova's answer used to be correct, but with AMD's SEV, it no longer is: https://security.stackexchange.com/a/241566/84564

Amazingly it seems, that as long as you trust AMD's CPU, the rest of the hardware can be compromised.

Ole Tange
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