#oprf — Public Fediverse posts
Live and recent posts from across the Fediverse tagged #oprf, aggregated by home.social.
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I just published an RFC compliant Java implementation of OPAQUE/OPRF. OPAQUE provides authentication without the need to share the passwords... rendering server's authentication database useless for offline attacks. This implementation, with Typescript/Client support and Open API specs, can be found here: https://github.com/codeheadsystems/hofmann-elimination
I'd love to get a few eyes on it, looking for comments or security concerns. It's Apache 2 licensed and I'd love to get this (or something like it) everywhere to reduce the value of powning servers. I plan more ports to other languages, go, rust, c#.
#Java #Authentication #cryptography #infosec #opaque #oprf #rfc
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in liboprf we have an updatable OPRF without using a pairing, and with klutschnik we have a project that does updatable public key encryption, for data at rest. why is their upstream academic research not even mentioned in this paper: https://eprint.iacr.org/2025/175
Hugo Krawczyk is even a colleague of some of these authors.
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evolution of generative password "storage" over the last decades:
1. "password"
2. hash("password")
3. hmac("password", site)
4. oprf("password"+site, sphinx-oracle)
5. t-oprf(password+site, [sphinx-oracle1, sphinx-oracle2, ... sphinx-oracleN])#crypto #oprf #passwordmanager
check out https://sphinx.pm, v2 with threshold oprf coming soon...
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with the help of @vegetables i finally got it working. i had two off-by-ones, and i was messing up the generation of the commitments. \o/ robust updatable threshold oprfs here i come! expect some code hitting the liboprf repo soon.
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for liboprf i try to implement the robust multiparty multiplication from Genarro,Rabin,Rabin '98. I struggle with implementing a check (the paper calls VSPS property). I asked the original authors 2 months ago, but they don't reply - i guess they're busy. I wrote up the relevant part of the paper, and my confusion and questions in this simple text (best viewed with a fixed with font!): https://ctrlc.hu/~stef/vsps_check.mail.txt - any help would be appreciated.
#crypto #multiparty #mpc #oprf -
just prototyped this 3hashtdh from https://eprint.iacr.org/2024/1455 in python using pyoprf, and it is surprisingly simple and elegant. really looking forward to add it properly to liboprf. adding the t-opaque from the paper is a childs play, for each "target server" one additional hkdf call is all that is necessary besides using 3hashtdh...
https://github.com/stef/liboprf/blob/master/python/3hashtdh.py#L16-L21 -
hah! a paper on #threshold #oprf and threshold #opaque by jarecki et al, although krawczyk is missing from the team, it still will be interesting to see how far their paper is from my toprf and topaque implementations. https://eprint.iacr.org/2024/1455
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@eprint what they fail to say in the title, they claim to be post-quantum, and can do this in less than a second on consumer-grade hw...
(re: https://ia.cr/2024/1032)
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addendum to my #blogpost about a nifty attack against #sphinx and other #oprf-based protocols, i published a simple PoC of the #attack: https://github.com/stef/liboprf/blob/master/misc/attack.c
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i wrote a blog post about a nifty attack on #SPHINX and (possibly other OPRF-based protocols):
https://ctrlc.hu/~stef/blog/posts/A_nifty_attack_on_SPHINX_and_other_OPRF-based_systems.html
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woohooo, finally SPHINX has a dedicated website: https://sphinx.pm/ - it's still a bit immature, but it is a start.
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asciimoo is applying some much needed love to the websphinx browser addons. if all goes well there will be one addon for both chrome and firefox - and there will be webauthn support via sphinx...
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wow, threshold-sphinx is a thing! just managed to get a password for which the oprf key has been created by a dkg. not that we knew this is possible, sure. but now i have working code doing so! still a lot of work until this can be deployed, but it is very promising start! #sphinx #oprf #threshold #passwordmanager #nlnet #ngi0
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quite awesome work: https://eprint.iacr.org/2023/639 with all their code available: https://github.com/meyira/OIDA - they instantiate a #postquantum #OPRF from #CSIDH - while also doing so using Naor-Reingold PRF with oblivious transfer. And finally they instantiate a post-quantum #OPAQUE and compare it to my implementation - admittedly the pqOPAQUEs are much much slower, but it is still awesomely cool that this is possible! i'm sure there is room for improvements here.
kudos!
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good news everyone ICYMI, there is now an #RFC for hash-to-curve! https://www.rfc-editor.org/info/rfc9380 this is an essential #crypto building block for OPRFs based on hashDH construction. something like this has been lacking for 20 years, finally were there. now onwards to #oprf rfc and #opaque rfc!
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i just uploaded my #slides for my #oprf talk from #cccamp23 to https://pretalx.c3voc.de/camp2023/talk/KG9EEV/ and also to https://ctrlc.hu/~stef/fantastic-oprfs.pdf
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new paper adding to the #postquatum #OPRF literature: https://eprint.iacr.org/2023/1176
they use garbled circuits with some pq prf, to achieve better results than the rest of these attempts, and aim for #universal #composability, but still are quite far from the half-pq (2)hashDH construction. #crypto
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Good news everyone! Both of my talks (talk1: oprfs, talk2: klutshnik) from #camp++ a few weeks ago have been published at https://camp.hsbp.org/2023/pp7e7/recordings.html #crypto #presentation #oprf #klutshnik