I’m a data scientist with an interest in History, Cryptography and AI - so naturally when I started seeing posts about AI solving ancient mysteries, I had to try myself. It started with breaking a few, and has snowballed into the largest systematic effort to fully decipher as much of early-modern diplomatic ciphers as possible - with the newfound powers of Claude Code. CYPHERSOLVER is an informal benchmark of frontier models on “unsolved” historical ciphers, pulled from archives across the internet. Visit my site to read all the juciest details and contribute In 6 weeks, a community of 15+ (and growing) Claude Coders (and occasionally Codex), including the worlds greatest codebreaker, have attempted 460+ ciphers (largely covering 1400-1900 Europe) with approx a 80% success of either solving them or finding the existing answer buried in the archives. Claude is incredible at archival research, which was the bulk of the readings. However Claude is also very good (world class) at cryptanalysis and breaking a cipher with ciphertext only. Claude builds small purpose-built solvers (annealers, n-gram language models) specific to each problem, and builds upon prior solutions in the repository to quickly narrow down its hypothesis testing. Claude is also amazing at transcription, even of obscure glyphs and difficult to read 600 year old manuscripts. We’ve had to build various validation and verifcation standards across the website, including many skills which cover verification and writeups. The models arent perfect- mistakes can be made on transcription and some signs get revised after multiple attempts. Claude is often a very poor estimater of its probability of solving a problem. A concrete ‘not solvable’ declaration can quickly fall when it gets past the blockers. It will often stop short of a complete solution, needing encouragement and prodding to continue. However, most of the time I just use the /goal function (keeps Claude working until it’s reached a goal) and solve a cipher in 20-60 min. Some take hours and hours. Opus 5.5 on low setting is also plenty strong enough. Want to contribute? While we are rapidly draining the worlds open unsolved ciphers, many many solutions are partial and contributers can attempt to push them further and receive credit from the website. Send a issue or PR request to the repo and I’ll review, merge and give you credit! Processing img c7zcji4zbqxh1… [This post was written by hand, referencing a rough outline from Claude] submitted by /u/AdOk8143
Originally posted by u/AdOk8143 on r/ClaudeCode