Timeline for What is a randomly derived key?
Current License: CC BY-SA 4.0
10 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Aug 14, 2019 at 12:37 | vote | accept | Zaphod | ||
| Aug 14, 2019 at 11:44 | comment | added | Gilles 'SO- stop being evil' | @Zaphod Yes, as long as the two keys are distinct, it's ok to use the same nonce with both. | |
| Aug 14, 2019 at 11:00 | comment | added | Zaphod | Thanks for the edit, it's clearer now. I understand that deriving a new key from a unique password but different random salt for each message, with Argon2i for instance, may not be the best thing to do in practice. However, on a theoretical perspective, is it secure to do so ? Can the same nonce be used with two of these keys ? | |
| Aug 13, 2019 at 20:16 | comment | added | Gilles 'SO- stop being evil' | @Zaphod I rewrote the sentence. Actually, I rewrote the whole paragraph, because it was missing an important step. Since K is a key and not a password, there's no point in using Argon2 on it: save the heavy computations for the things that need them. Don't derive multiple keys from the same password and different salts unless you have a very good reason to treat those operations as using different passwords where the user happened to have reused the password. It makes key management harder and uses a lot more CPU without any security benefit. | |
| Aug 13, 2019 at 20:14 | history | edited | Gilles 'SO- stop being evil' | CC BY-SA 4.0 |
added 1 character in body
|
| Aug 13, 2019 at 20:06 | history | edited | Gilles 'SO- stop being evil' | CC BY-SA 4.0 |
added 1 character in body
|
| Aug 13, 2019 at 20:06 | comment | added | Zaphod | I also just noticed you probably meant $\approx 2^{-32}$ instead of $\approx 2^{32}$ if I'm correct. | |
| Aug 13, 2019 at 20:05 | history | edited | Gilles 'SO- stop being evil' | CC BY-SA 4.0 |
added 1 character in body
|
| Aug 13, 2019 at 20:02 | comment | added | Zaphod | What do you mean by "use it with a per message or per conversation as the secret input" ? I feel like there is a missing word. Also what's the problem with using K directly ? Is it that it is derived from Argon2i and not KDF1/2 or HKDF ? Finally, if for each message I generate a new random 32-byte salt and derive a new key K' using Argon2i from this new salt and the same user-entered password, do I still need to make sure the nonces of each messages are distinct ? | |
| Aug 13, 2019 at 17:39 | history | answered | Gilles 'SO- stop being evil' | CC BY-SA 4.0 |