Posts
Signal Foundation: Introducing Signal Secure Backups
Lessons learned from doing cryptographic research with ChatGPT
Perceptual hashing
As the Chat Control vote nears, it's worth skimming the [perceptual hashing](https://en.wikipedia.org/wiki/Perceptual_hashing) literature. All have easy preimage atacks, nevermind second-preimage. Adversaries can simply select a base image already circulating among the group they wish to target, create an image they could enter into the database, with a colliding perceptual hash, …
Prime Predictor & Generator: Verifiable PoC for Crypto-Grade Primes
\*\* This post was reformatted by Grok 4 \*\*\* Two months deep in number theory, I've crafted a C-based Z5D predictor and generator in the Z Framework (Z=A(B/c)), fusing PNT with Miller-Rabin verification, Z-corrections (c=-0.00247, k\*=0.04449), and φ-geodesic density mapping. PoC on Apple M1 Max; all claims from repro runs …
Question about how to maintain a shared key for symmetric key encrypted messages between a group of devices ?
I am building a kind of shared scratchpad that I can sync between my Mac, my windows pc and my linux home server. I will be using an external database for on-demand sync. I want E2E encryption. For the rest of this post, please forgive my ignorance of crypto research. …
Why does RFC 7748 use AA instead of BB in the doubling formula for Curve25519?
I’ve been studying the Montgomery ladder formulas for Curve25519, starting from the standard doubling formula in projective coordinates: https://preview.redd.it/0o0exl2f7jmf1.png?width=492&format=png&auto=webp&s=8492c1012e72f5f3d0fe06d0d37ac2802ade1bad When you translate this into the RFC 7748 notation: A = x_2 + z_2 AA = A^2 B = x_2 - z_2 BB = B^2 E = AA - BB z_2 …
Inverting the Xorshift128+ random number generator
ToyCrypto v0.5.0: A Python project for illustrating some cryptographic concepts
Zero-Knowledge Proofs Beyond Transactions: Can We Prove Processes Instead of Just Data?
I've looked thru the discussion on r/Crypto on Zero-Knowledge, and I think there are so many angles to this topic that lots of users could chime in on the conversation. Most ZK conversations focus on transactions, hiding balances, scaling rollups, or anonymous IDs. But what if Zero-Knowledge could move from …
I made a password book generator
Code: [https://github.com/zeorin/passwordbook](https://github.com/zeorin/passwordbook) I have [already posted this](https://www.reddit.com/r/cryptography/comments/1mxcax4/i_made_a_password_book_generator/) on r/cryptography and gotten some useful feedback, but I'm still looking for more. 😁 Current implementation: Seed passprase is generated as per bip39, and then its bits are used to derive a key using PKDF2 with a salt, sha512, and 2^(18) iterations; and …