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The private key should ideally never leave the SmartCard.


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On the client side you could use PBKDF2 or a similar key derivation function to generate a key to then use to encrypt/decrypt the symmetric key before using it. Would this be considered (acceptably) safe? This really depends on a few things: 1. What is the threat model? Who are you trying to prevent from attacking you? A nation state? A jealous ...


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This setup is trying to match domains and ssl keys. However, I would start by questioning what are ‘domains’ here why are they important. Could the domain simply be a hash of the ssl key? That way you no longer need the CA. How are the domains assigned? If they are centrally assigned, could the ssl signing be simply provided as one step of the domain ...


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In light of the broad question I will concentrate on answering your more specific one regarding full access to the centralised server. I'll refer to said server as a CA because this is essentially what you are describing. TL; DR it depends Let's presume that full access means knowledge of the CA's private key. This may not always be the case if we consider ...


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I'm not a programmer but i think that if you don't want people having access to your code then you need to make it server-side, code executed in the client side, must be available not-encrypted on the client side at some point. This is exactly like DRM: you're giving the user a lock, and also the key to it, and expecting to be able to say what they can do ...


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is it really necessary worrying about superusers? My gut feeling says no: in princible whathever the encryption method a superuser can read all the files and ultimately any kind of keys of the users; Kind of. Even if the file is encrypted and the decryption is only done within the process the superuser has on most systems access to the process memory ...


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Yolen described his motivation with existing examples in presentaion of LISA 2013, "Managing Access Using SSH Keys". https://www.usenix.org/conference/lisa13/managing-access-using-ssh-keys https://www.usenix.org/sites/default/files/conference/protected-files/ylonen_lisa13_slides.pdf In the presentation as well as NISTIR 7966, they don't mentioned separate ...


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The short answer is "They are very very careful 'where' the private keys are." I think you may be misunderstanding or ignoring a basic part of how these kinds of keys work - when you sign something, it's a one-way mathematical operation that "proves" it was signed by one particular entity. (Technically, someone with access to said key, and knowledge of any ...


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The real question is whether you're using a signing/authentication GPG subkey as your SSH key, or an encryption one. The former is fine, the latter is not: an RSA key must never be used to both encrypt and sign! (Authentication uses digital signatures.)


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Secret keys (symmetric or asymmetric) are typically stored in an encrypted medium of some sort such as a keystore or encrypted database. Specific example of a keystore would be the JKS (Java Key Store), and a database would be SQLCipher. This encrypted medium is secured with a password, which is needed in order to read/write to it. SQLCipher will first churn ...


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First, it's no problem to use a different symmetric key for each document, generation is easy as you just have to generate a 16-64 byte random string, a matter of a millisecond (mostly). As threats I guess you consider your cloud hoster and anyone who can get their hands on the documents. The approach you propose should work. The document needs to be ...


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Firstly, often encryption is terminated at the perimeter by infrastructure which is dedicated to offloading SSL decryption. It makes it much easier to manage when you only have maintain a high degree of key security for a small (proportionally) group of servers which are dedicated to the role. The rest of your regular application servers can operate like ...


43

Technically, changing your passphrase is sufficient if you don't also believe that your (password-protected) private key has also been leaked. Realistically, you might just want to replace your SSH key with a new one. They're so cheap they might as well be free, and it removes you from worrying about whether anyone has, is, or will be able to get a copy of ...


18

Changing the passphrase of an existing key can be done with: ssh-keygen -p ...you are however not done by now. You also have to take consider copies of your old keys, these need to be removed or it should be treated as compromised. Think of backups, but also data on filesystems (copy-on-write filesystems such as ZFS and btrfs could keep a copy somewhere ...


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Short of asking the Certificate Authorities yourself (preferably with a secondary list of valid CRL and or OCSP download URL's lists) one by one I know none. You could script that, or you could recreate the Repository and create a hash of it. Also checking if the checksums are valid can give you a clue (although it does not show a replaced certificate / ...


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Instead of using a hardcoded key, you should use mutual SSL authentication. Using an obfuscated key, doesn't add any security, certainly not when you're already using SSL.


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I think there is an additional problem/challenge with your scheme: Beside the problem of having the key pairs generated by the server, this scheme also allows for a man in the middle attack: A asks for the key of B, server answers with his own key C. Now the server can decrypt, read and encrypt again for B and send the new ciphertext to B. Neither A nor B ...


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Let me make sure I understand. Your user will run a local application that is capable of decrypting your encrypted file and of storing it (or parts of it) in memory in a readable format. Your adversary is the user; the user is assumed to want to hijack those permissions stored in the encrypted file. I also assume the user is root on that machine so she can ...



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