On 7/19/21 10:51 AM, Stephan Mueller wrote: > Am Montag, dem 19.07.2021 um 10:15 +0200 schrieb Hannes Reinecke: >> On 7/18/21 2:56 PM, Stephan Müller wrote: >>> Am Sonntag, 18. Juli 2021, 14:37:34 CEST schrieb Hannes Reinecke: > >>>> The key is also used when using the ffdhe algorithm. >>>> Note: I _think_ that I need to use this key for the ffdhe algorithm, >>>> because the implementation I came up with is essentially plain DH with >>>> pre-defined 'p', 'q' and 'g' values. But the DH implementation also >>>> requires a 'key', and for that I'm using this key here. >>>> >>>> It might be that I'm completely off, and don't need to use a key for our >>>> DH implementation. In that case you are correct. >>>> (And that's why I said I'll need a review of the FFDHE implementation). >>>> But for now I'll need the key for FFDHE. >>> >>> Do I understand you correctly that the dhchap_key is used as the input to >>> the >>> DH - i.e. it is the remote public key then? It looks strange that this is >>> used >>> for DH but then it is changed here by hashing it together with something >>> else >>> to form a new dhchap_key. Maybe that is what the protocol says. But it >>> sounds >>> strange to me, especially when you think that dhchap_key would be, say, >>> 2048 >>> bits if it is truly the remote public key and then after the hashing it is >>> 256 >>> this dhchap_key cannot be used for FFC-DH. >>> >>> Or are you using the dhchap_key for two different purposes? >>> >>> It seems I miss something here. >>> >> No, not entirely. It's me who buggered it up. >> I got carried away by the fact that there is a crypto_dh_encode_key() >> function, and thought I need to use it here. > > Thank you for clarifying that. It sounds to me that there is no defined > protocol (or if there, I would be wondering how the code would have worked > with a different implementation). Would it make sense to first specify a > protocol for authentication and have it discussed? I personally think it is a > bit difficult to fully understand the protocol from the code and discuss > protocol-level items based on the code. > Oh, the protocol _is_ specified: https://nvmexpress.org/wp-content/uploads/NVM-Express-Base-Specification-2_0-2021.06.02-Ratified-5.pdf It's just that I have issues translating that spec onto what the kernel provides. Cheers, Hannes -- Dr. Hannes Reinecke Kernel Storage Architect hare@xxxxxxx +49 911 74053 688 SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg HRB 36809 (AG Nürnberg), GF: Felix Imendörffer
