r/crypto

Is it correct to state that the Pedersen hash system isn t vulnerable to length extension attack as long as the inputs are a multiple of the number of window s bits?

The original description can be found [here](https://iden3-docs.readthedocs.io/en/latest/iden3_repos/research/publications/zkproof-standards-workshop-2/pedersen-hash/pedersen.html). I m studying the hash for existing systems still using it (the input is then at least 496bits long). My understanding though is if there s no padding, then it s impossible to …

How secure is hardware-based cryptography?

im working with cryptography and there are functions exposed from the hardware to the application. (not relevant, but so you have context) [https://developer.mozilla.org/en-US/docs/Web/API/SubtleCrypto](https://developer.mozilla.org/en-US/docs/Web/API/SubtleCrypto) this is working as expected. under-the-hood it is optimised with the hardware and i can see that …

WhatsApp Clone... But Decentralized and P2P Encrypted Without Install or Signup

By leveraging WebRTC for direct browser-to-browser communication, it eliminates the middleman entirely. Users simply share a unique URL to establish an encrypted, private channel. This approach effectively bypasses corporate data harvesting and provides a lightweight, disposable communication method for those …

In diffie Hellman, is it possible to modify linear combinations so the end result is a multiple of the first result? Does this type of Diffie Hellman problem has a specific name?

Let s say I ve `D=i×A+n×B+k×C` like `D=55×A+36×B+578×C` over an elliptic curve with a large prime number and the discrete logarithm between each point being unknown. If `i` is a whitelisted constant, is it possible to modify `n` and `k` …

Review request: combining age (scrypt passphrase) with Shamir secret sharing for offline, browser-based recovery

Hi r/crypto, I’m looking for technical critique of a small tool I built that combines **age** encryption with **Shamir’s Secret Sharing** and a **self-contained browser recovery tool**. Repo: [https://github.com/eljojo/rememory](https://github.com/eljojo/rememory) Docs: [https://eljojo.github.io/rememory/docs.html](https://eljojo.github.io/rememory/docs.html) # Problem I’m trying to solve How can non-technical …

Collision Resistance of HMACs

Hi everyone. I am studying HMACs and I just wanted to double-check: the collision resistance of an HMAC checksum is roughly half of the bit size of the checksum itself, right? So for example HMAC-SHA-256 has a collision resistance of …

Is there a way to modify this elliptic curve diffie Hellman equation like this?

Let s denote `e()` a bilinear elliptic curve pairing. Let s say I have `e(-A,B)==e(C,D)` or `e(A,B)*e(C,D)==1` where *C* and *A* are in G1 and *B* and *D* in G2. Without knowing the discrete logarithms between the points, I can …

Chat Control is being pushed again

What s the shortest possible number of Miller loops for bn254 and bls12-381 elliptic curves for getting a bilinear pairing?

There s many paper that explore making bilinear pairings efficient, but as far I understand, they also aim at making the final exponentiation simpler. In my case I [have an inversion algorithm whose complexity is if I understand correctly O(k(2^(s^²)))^(3.3k))](https://drive.google.com/file/d/1SXS1h-6Tywdj9_1XlMRhrS0piHl7DrLG/view). …

Are there any good tutorials on post-quantum cryptography?

as the title says. id like to learn more. there are a few videos out there, but i havent come across something like an article or practical tutorial that explains it. perhaps there is a book or something you'd suggest …