cryptography

Unlike Caesar, each letter is replaced by a different letter according to an arbitrary mapping (not a simple shift). We solve it by comparing the letter frequency of the ciphertext to the known letter frequency in English, and guessing short words ( the , and , a ...). Platform: picoGym Category: Cryptography Points: 150 pts Difficulty: Beginner Technique: Monoalphabetic substitution, frequency a…

LatticeJolt, a new version of the open-source zkVM Jolt, now utilizes lattice cryptography instead of elliptic curves.

The Caesar cipher has exactly 26 possible shifts (modulo the 26 letters of the alphabet). A Python script that tests all 26 shifts and looks for picoCTF in the result finds the right one in a fraction of a second. Platform: picoGym Category: Cryptography Points: 100 pts Difficulty: Beginner Technique: Caesar cipher, brute force Challenge description The challenge provides a ciphertext and a hint …

A hash chain proves a record was not modified after it was written. It does not prove when it was written, and it does nothing against someone who controls the server and can re-sign the whole chain. RFC 3161 trusted timestamps close that gap. This is a practical look at what they are, how to wire them in, and where the footguns are. The gap a hash chain leaves open If you hash-chain your records…

IonQ used September 8, 2026 Investor Day to launch Superion 256, open 2027 deliveries, and raise 2026 revenue guidance to $450 million to $460 million after the SkyWater close. The same package included an $8.18 million Congruity360 quantum-safe networking agreement and a fully compiled Walking Cat estimate putting secp256k1 at 19,397 physical qubits and 25.7 days per attempt. Error-correction pa…

Over the past few weeks, the Cognition research team and I have been optimizing our job scheduler to better use disaggregated compute. As a proof of concept, and because I’ve enjoyed factoring numbers as a hobby for the past ten years or so, I drove a bevy of Devins to obtain a factorization of RSA-260. In order to do this, my Devins built the world's highest-performance GPU lattice siever, which…

Scientific Reports, Published online: 09 September 2026; doi:10.1038/s41598-026-70703-2 Reversible cross-channel coupling and dynamic diffusion for secure chaos-based color image encryption

On the morning of 3 September 2026, Eric Lu posted a 130-digit integer on X and added four words: divides RSA-260. Eric apparently factored it, but we still do not know exactly how and are still waiting for an update. That was the paper. No lab announcement, no runtime, no cluster size. By afternoon, people had divided the published modulus on laptops, both factors had passed primality tests, and…

I’ve factored the RSA keys of a Certificate Authority... … from the 90s. I’ve been thinking about the security of RSA lately. RSA’s cryptography relies on the difficulty of factoring a large semiprime number, but what “large” means is an interesting question. The Web PKI deprecated 1024-bit RSA over a decade ago, and while I don’t know of anyone factoring a key of that size, it’s within the realm…