--- title: Claude found mathematical flaws in two cryptographic... description: Anthropic's Claude Mythos Preview has discovered mathematical weaknesses in two cryptographic algorithms: it halved the effective key strength of HAWK, a... canonical: https://daily.dev/posts/claude-found-mathematical-flaws-in-two-cryptographic-algorithms-that-years-of-expert-review-missed-atikdbjvh twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Claude found mathematical flaws in two cryptographic algorithms that years of expert review missed | daily.dev og:description: Anthropic's Claude Mythos Preview has discovered mathematical weaknesses in two cryptographic algorithms: it halved the effective key strength of HAWK, a... og:url: https://daily.dev/posts/claude-found-mathematical-flaws-in-two-cryptographic-algorithms-that-years-of-expert-review-missed-atikdbjvh og:image: https://api.daily.dev/og/posts/atikDBjvH.png og:image:alt: Claude found mathematical flaws in two cryptographic algorithms that years of expert review missed og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Claude found mathematical flaws in two cryptographic algorithms that years of expert review missed **[The Next Web](https://daily.dev/sources/tnw)** · 3 min read · 2 upvotes · 0 comments ## Summary Anthropic's Claude Mythos Preview has discovered mathematical weaknesses in two cryptographic algorithms: it halved the effective key strength of HAWK, a post-quantum digital signature scheme under NIST review, and improved the best-known attack on seven-round AES by 200-800x. Neither flaw affects production systems. HAWK survived two years of expert NIST review; Claude found the weakness in 60 hours of semi-autonomous work. The AES result was found almost entirely autonomously after Claude initially refused, with a researcher sending just three encouraging prompts over three days. Each discovery cost ~$100K in compute. Anthropic followed responsible disclosure, coordinating with NIST and industry partners, and released CryptanalysisBench alongside ETH Zurich and other universities to benchmark AI cryptanalytic capabilities. Additional follow-up results include attacks on LEA, Serpent-128, Salsa20, Poseidon, and SHA-1. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What cryptographic weakness did Claude Mythos find in HAWK? Claude Mythos discovered a mathematical flaw that cuts HAWK's effective key strength in half. HAWK is a post-quantum digital signature scheme under review by NIST that had survived two rounds of NIST review over two years; Claude found the weakness in about 60 hours of semi-autonomous work, with a human researcher only providing project management direction rather than technical guidance. _daily.dev helps security engineers track how AI-driven cryptanalysis is reshaping algorithm review._ ### How much faster is the new attack on reduced-round AES found by Claude? The attack improves the best-known attack on seven-round AES by 200 to 800 times, discovered almost entirely autonomously after Claude initially refused, claiming improvement was impossible. Three encouraging prompts over three days led it to produce one billion output tokens and invent a new technique called the Möbius Bridge. The attack targets a reduced-round variant, not full AES, so production systems are unaffected. _engineers weighing cipher risk can follow AES cryptanalysis developments on daily.dev._ ### How much did it cost to discover these AI-found cryptographic weaknesses? Each discovery cost approximately $100,000 in API compute. Anthropic followed responsible disclosure practices, sharing the HAWK attack with its authors and coordinating with NIST, the US government, and industry partners before publishing, and also released CryptanalysisBench with ETH Zurich, Tel Aviv University, and University of Haifa to benchmark AI cryptanalytic capability. _teams evaluating AI security research costs can track this space on daily.dev._ ## Similar posts on daily.dev - [Claude Mythos Preview Exposes Hidden Code Flaws Fast](https://daily.dev/posts/claude-mythos-preview-exposes-hidden-code-flaws-fast-wdwyjdo3x) · IEEE Spectrum · 0 upvotes · 0 comments - [Claude Mythos Preview \\ red.anthropic.com](https://daily.dev/posts/claude-mythos-preview-red-anthropic-com-wkjczmbgu) · Hacker News · 5 upvotes · 0 comments --- Tags: [#quantum-computing](https://daily.dev/tags/quantum-computing), [#claude](https://daily.dev/tags/claude), [#anthropic](https://daily.dev/tags/anthropic), [#cryptography](https://daily.dev/tags/cryptography) [View this post on daily.dev](https://daily.dev/posts/claude-found-mathematical-flaws-in-two-cryptographic-algorithms-that-years-of-expert-review-missed-atikdbjvh) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Claude found mathematical flaws in two cryptographic algorithms that years of expert review missed","url":"https://daily.dev/posts/claude-found-mathematical-flaws-in-two-cryptographic-algorithms-that-years-of-expert-review-missed-atikdbjvh","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/claude-found-mathematical-flaws-in-two-cryptographic-algorithms-that-years-of-expert-review-missed-atikdbjvh"},"datePublished":"2026-07-28T19:58:26.603Z","dateModified":"2026-09-13T19:05:21.002Z","description":"Anthropic's Claude Mythos Preview has discovered mathematical weaknesses in two cryptographic algorithms: it halved the effective key strength of HAWK, a...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/6eaa51aea474b33e1247e2fb0c938f19?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/6eaa51aea474b33e1247e2fb0c938f19?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"The Next Web","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"The Next Web","logo":"https://media.daily.dev/image/upload/t_logo,f_auto/v1/logos/tnw","url":"https://daily.dev/sources/tnw"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/claude-found-mathematical-flaws-in-two-cryptographic-algorithms-that-years-of-expert-review-missed-atikdbjvh","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":2},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"quantum-computing,claude,anthropic,cryptography","timeRequired":"PT3M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"The Next Web","item":"https://daily.dev/sources/tnw"},{"@type":"ListItem","position":3,"name":"Claude found mathematical flaws in two cryptographic algorithms that years of expert review missed"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/claude-found-mathematical-flaws-in-two-cryptographic-algorithms-that-years-of-expert-review-missed-atikdbjvh#faq","mainEntity":[{"@type":"Question","name":"What cryptographic weakness did Claude Mythos find in HAWK?","acceptedAnswer":{"@type":"Answer","text":"Claude Mythos discovered a mathematical flaw that cuts HAWK's effective key strength in half. HAWK is a post-quantum digital signature scheme under review by NIST that had survived two rounds of NIST review over two years; Claude found the weakness in about 60 hours of semi-autonomous work, with a human researcher only providing project management direction rather than technical guidance. daily.dev helps security engineers track how AI-driven cryptanalysis is reshaping algorithm review."}},{"@type":"Question","name":"How much faster is the new attack on reduced-round AES found by Claude?","acceptedAnswer":{"@type":"Answer","text":"The attack improves the best-known attack on seven-round AES by 200 to 800 times, discovered almost entirely autonomously after Claude initially refused, claiming improvement was impossible. Three encouraging prompts over three days led it to produce one billion output tokens and invent a new technique called the Möbius Bridge. The attack targets a reduced-round variant, not full AES, so production systems are unaffected. engineers weighing cipher risk can follow AES cryptanalysis developments on daily.dev."}},{"@type":"Question","name":"How much did it cost to discover these AI-found cryptographic weaknesses?","acceptedAnswer":{"@type":"Answer","text":"Each discovery cost approximately $100,000 in API compute. Anthropic followed responsible disclosure practices, sharing the HAWK attack with its authors and coordinating with NIST, the US government, and industry partners before publishing, and also released CryptanalysisBench with ETH Zurich, Tel Aviv University, and University of Haifa to benchmark AI cryptanalytic capability. teams evaluating AI security research costs can track this space on daily.dev."}}]} ```