Questions, answers, discussions, and literature on the theory and practice of cryptography
Rules (longer version here)
##Related resources;
Draft: Hybrid Post-Quantum Password Authenticated Key Exchange
This document describes the CPaceOQUAKE+ protocol, a hybrid asymmetric password-authenticated key exchange (aPAKE) that supports mutual authentication in a client-server setting secure against quantum-capable attackers. CPaceOQUAKE+ is the result of a KEM-based transformation from the hybrid symmetr...
Announcement from here;
https://mailarchive.ietf.org/arch/msg/cfrg/_HH9A70BwJ6vgEfT2iSTvCQFhZE/
Hi folks,
We recently published an initial specification for a hybrid, post-quantum, augmented PAKE protocol, called CPaceOQUAKE+, located here:
https://datatracker.ietf.org/doc/draft-vos-cfrg-pqpake/
The motivation for this protocol can be roughly summarized as follows:
- Post-quantum: None of the existing PAKE specifications are post-quantum. Rather than incrementally improve on PAKEs that are secure against standard adversaries, we felt it important to shift focus to post-quantum adversaries.
- Augmented: Many PAKE deployments use augmented PAKEs (SRP and SPAKE2+, for example). A drop-in replacement for these use cases was therefore important.
- Hybrid: CPaceOQUAKE+ is built on CPace and OQUAKE (which is specified in the document and based on the NoIC protocol in [1], and then composed with CPace using a variant of the combiner analyzed in [3]) as well as other
Apple can now legally talk about the UK backdoor demand
Apple has won its first legal battle over the UK’s demand for a backdoor to encrypted data: the right to tell everyone it’s happening. The Investigatory Powers Tribunal has ruled on whether Apple’s claim should be kept secret on national security grounds, and Apple won. That doesn’t bring it any clo...
CRLite is a low-bandwidth, low-latency, privacy-preserving mechanism for distributing certificate revocation data. A CRLite aggregator periodically encodes revocation data into a compact static hash set, or membership test, which can can be downloaded by clients and queried privately. We present a n...
See also discussion here; https://reddit.com/comments/1jv572r
Key-exfiltration attacks on cryptographic keys are a significant threat to computer security. One proposed defense against such attacks is big-key cryptography which seeks to make cryptographic secrets so large that it is infeasible for an adversary to exfiltrate the key (without being detected). Ho...
Cryptology ePrint Archive
Paper 2025/585
Adaptively-Secure Big-Key Identity-Based Encryption
Jeffrey Champion, The University of Texas at Austin
Brent Waters, The University of Texas at Austin, NTT Research
David J. Wu, The University of Texas at Austin
Abstract
Key-exfiltration attacks on cryptographic keys are a significant threat to computer security. One proposed defense against such attacks is big-key cryptography which seeks to make cryptographic secrets so large that it is infeasible for an adversary to exfiltrate the key (without being detected). However, this also introduces an inconvenience to the user who must now store the large key on all of their different devices. The work of Döttling, Garg, Sekar and Wang (TCC 2022) introduces an elegant solution to this problem in the form of big-key identity-based encryption (IBE). Here, there is a large master secret key, but very short identity keys. The user can now store the large master secret key as her long-t
In this paper, we present the first practical algorithm to compute an effective group action of the class group of any imaginary quadratic order $\mathcal{O}$ on a set of supersingular elliptic curves primitively oriented by $\mathcal{O}$. Effective means that we can act with any element of the clas...
Abstract;
In this paper, we present the first practical algorithm to compute an effective group action of the class group of any imaginary quadratic order
Oon a set of supersingular elliptic curves primitively oriented byO. Effective means that we can act with any element of the class group directly, and are not restricted to acting by products of ideals of small norm, as for instance in CSIDH. Such restricted effective group actions often hamper cryptographic constructions, e.g. in signature or MPC protocols.
Our algorithm is a refinement of the Clapoti approach by Page and Robert, and uses 4-dimensional isogenies. As such, it runs in polynomial time, does not require the computation of the structure of the class group, nor expensive lattice reductions, and our refinements allows it to be instantiated with the orientation given by the Frobenius endomorphism. This makes the algorithm practical even at security levels as high as CSIDH-4096. Our implementation in SageMath ta
Indiana University quietly removes profile of tenured professor and refuses to say why.
A collection of my (future) writings about cryptography, music and other random stuff.
Via; https://bsky.app/profile/nicksullivan.org/post/3ll7galasrc2z
CFRG process documentation has been updated.
Internet discussions about end-to-end encryption are plagued by misunderstandings, misinformation, and some people totally missing the point. Of course, people being wrong on the Internet isn’…
Prepping for post-quantum: a beginner's guide to lattice cryptography
This post is a beginner's guide to lattices, the math at the heart of the transition to post-quantum (PQ) cryptography. It explains how to do lattice-based encryption and authentication from scratch.
A living document on how to juggle these damned things. Updated March 19, 2025. What’s a KEM? A KEM is a Key Encapsulation Mechanism, a cryptographic...
Apple has revealed a Passwords app vulnerability that lasted for months - No HTTPS, enabling phishing on untrusted networks
The iOS Passwords app was a phishing attack vector.
(With severe apologies to Miles Davis.) Post-Quantum Cryptography is coming. But in their haste to make headway on algorithm adoption, standards organizations (NIST, IETF) are making a dumb mistake…
ePrint: SNARKs for Stateful Computations on Authenticated Data
We present a new generalization of (zk-)SNARKs combining two additional features at the same time. Besides the verification of correct computation, our new SNARKs also allow, first, the verification of input data authenticity. Specifically, a verifier can confirm that the input to the computation or...
From: https://mastodon.social/@fj/114171907451597856
Interesting paper co-authored by Airbus cryptographer Erik-Oliver Blass on using zero-knowledge proofs in flight control systems.
Sensors would authenticate their measurements, the control unit provides in each iteration control outputs together with a proof of output correctness (reducing the need in some cases for redundant computations), and actuators verify that outputs have been correctly computed
Building bridges without blue bubbles.
"The GSM Association announced that the latest RCS standard includes E2EE based on the Messaging Layer Security (MLS) protocol, enabling interoperable encryption between different platform providers for the first time"
IR 8545, Status Report on the Fourth Round of the NIST Post-Quantum Cryptography Standardization Process | CSRC - HQC gets standardized for post-quantum cryptography
NIST is selecting public-key cryptographic algorithms through a public, competition-like process to specify additional digital signature, public-key encryption, and key-establishment algorithms to supplement FIPS 186-5, SP 800-56Ar3, and SP 800-56Br2. These algorithms are intended to protect sensiti...
HQC gets standardized, as an addition to ML-KEM (kyber). McEliece is out of the NIST process for two reasons, they consider it unlikely to be widely used, also ISO is considering standardizing it and they don't want to create an incompatible standard. If ISO does standardize it and it does see use, NIST is considering mirroring that standard (since lots of US agencies are bound to using NIST standards)