# ANALYSIS: Anthropic says it advanced post-quantum cryptanalysis, and no one has checked

> Anthropic published research, covered by The Hacker News on July 29, 2026 , claiming its Claude Mythos Preview model derived an end-to-end key-recovery attack against HAWK-256 , a third-round candidate in the NIST…

- Author: Maxime Marquette
- Publisher: MadMax (https://mad-max.co)
- Section: Analysis
- Published: 2026-07-29
- Canonical URL: https://mad-max.co/en/article/analysis-anthropic-says-it-advanced-post-quantum-cryptanalysis-and-no-one-has-ch

## Key takeaways

- Anthropic says HAWK-256's claimed work factor drops from 2^64 to 2^38, and publishes an implementation with a runtime of about 3 hours 42 minutes on a 96-core server.
- The company says larger variants HAWK-512 and HAWK-1024 remain practically out of reach, and that neither result affects currently deployed production systems.
- The AES claim is a 200 to 800 times speedup of a meet-in-the-middle attack on a reduced 7-round AES-128, not the standard 10-round version.
- The article notes that the degree of human guidance in the results is not fully disclosed, and that Anthropic's self-assessed safety claim also needs independent checking.
- The results were published by Anthropic alone, unlike the July 20 CryptanalysisBench benchmark, which had multi-institutional co-authorship.

Anthropic published research, covered by **The Hacker News** on **July 29, 2026**, claiming its **Claude Mythos Preview** model derived an end-to-end key-recovery attack against **HAWK-256**, a third-round candidate in the **NIST** post-quantum cryptography standardization process. **The published implementation** gives an expected runtime of about **3 hours and 42 minutes** on a 96-core server. *A key-recovery attack against a NIST candidate is not a detail buried in a research paper. It is the kind of claim that should draw scrutiny before it draws applause.*

According to Anthropic, the claimed **work factor** for recovering a HAWK-256 key drops from **2^64 to 2^38** — an **enormous reduction**, if confirmed, in the computational effort required to break the scheme. The company also claims a **200 to 800 times speedup** of an existing "meet-in-the-middle" attack against a reduced, 7-round version of **AES-128**, out of the standard's normal **10 rounds**.

This analysis examines what Anthropic has actually published, what **independent artifacts** allow outside researchers to verify, and what remains, as of publication, a **company statement** rather than a **peer-reviewed**, third-party-confirmed result.

## What Anthropic claims about HAWK-256

### A drop from an impractical to a theoretically feasible work factor

The claimed drop from a work factor of **2^64 to 2^38** for HAWK-256 represents, in cryptographic terms, a **massive reduction**: a work factor of 2^38 falls within a range some computing setups could realistically attempt, whereas 2^64 remains firmly in impractical territory for most attackers. **This gap** is the central technical claim driving the entire announcement.

Anthropic states this attack was derived by its **Claude Mythos Preview** model, framing the result as evidence of **AI systems' growing capacity** to independently discover novel cryptanalytic techniques, rather than merely applying **known methods** faster.

### Why HAWK-512 and HAWK-1024 remain out of reach

For the larger variants, **HAWK-512** and **HAWK-1024**, Anthropic's claimed logic-gate estimates drop respectively from **2^150 to 2^108** and from **2^288 to 2^182** — reductions that, however significant in relative terms, still leave both variants firmly in the range of **practically unbreakable** with current computing resources. *A reduction from astronomical to merely enormous is real progress on paper. It changes nothing for anyone actually trying to break the cipher today.*

**Anthropic itself** acknowledges this distinction: the HAWK-256 result is presented as more consequential precisely because its reduced work factor edges toward a range where **practical exploitation** becomes conceivable, unlike the **larger variants**.

## The second claim: an accelerated attack on reduced AES-128

### A speedup on a weakened version of the algorithm, not the real standard

The second result Anthropic claims is a **200 to 800 times speedup** of an existing meet-in-the-middle attack, but applied against **AES-128 reduced to 7 rounds**, not the full standard, which uses **10 rounds** in real-world deployment. **This distinction** matters enormously: AES-128 as actually deployed in production systems worldwide is not the version this attack targets.

The **claimed improvement** works by removing an **exhaustive search step** over 256 possibilities that the previous version of the attack required, a genuine **algorithmic refinement** if confirmed, but one that applies to an already **artificially weakened** test version of the cipher.

### Why Anthropic itself says this changes nothing in production

Anthropic explicitly states that neither of its two published results affects **currently deployed production systems**: the HAWK attack remains **exponential** in nature rather than a polynomial-time break, and the AES attack requires a number of chosen plaintexts that remains **practically impossible** to obtain in a real attack scenario. *The company that announced the discovery is also the one setting the limits of its consequences. That symmetry alone justifies an outside look.*

This **self-imposed caveat** is worth noting: Anthropic is not claiming to have broken **cryptography used in the real world** today, only to have found a **measurable theoretical weakening** of specific reduced or standardization-candidate variants.

## What can actually be independently verified

### A published implementation, a partial reproducibility

Anthropic published an **implementation** of the HAWK-256 attack, complete with the claimed **3 hour 42 minute runtime** on a specified 96-core server configuration — a level of **technical detail** that does allow, in principle, independent researchers to attempt reproduction of the result. **This transparency** distinguishes the claim from a purely **rhetorical announcement** with no verifiable substance.

However, publishing an implementation is not the same as having that implementation **independently run and confirmed** by a third party outside Anthropic. As of July 29, 2026, no publicly documented **independent reproduction** of either result had been reported.

### What NIST has said, and not said

As of **July 29, 2026**, **NIST** still lists **HAWK** as a third-round candidate in its post-quantum standardization process, with no **official reaction** to Anthropic's claims documented in the sources available for this analysis. *The body responsible for deciding HAWK's fate has said nothing yet. Its silence is not a confirmation, any more than it is a denial.*

This **absence of an official NIST response** means the claimed attack has not, as of this writing, been factored into any formal reassessment of HAWK's status in the standardization process — a process that moves on its own **institutional timeline**, independent of a single company's **press cycle**.

## The broader context: CryptanalysisBench

### A benchmark published one week earlier

Anthropic's announcement follows the **July 20, 2026** publication of **CryptanalysisBench**, a 191-task benchmark developed by researchers from **ETH Zurich**, **Anthropic**, the **University of Haifa**, **TU Berlin** and **Tel Aviv University**. **This multi-institutional collaboration** lends the benchmark itself a degree of **academic credibility** distinct from a single company's internal claims.

On that benchmark, five different AI models reportedly broke between **65% and 86%** of first-level cryptographic schemes, according to the results published alongside the **benchmark's release** — a result that, unlike the HAWK and AES claims, benefits from **multi-institutional academic co-authorship**.

### Why the benchmark's credibility does not automatically transfer to the later claims

The fact that **CryptanalysisBench** involved credible academic partners does not mean every subsequent claim Anthropic publishes using models tested on that benchmark inherits the same level of **independent verification**. *A credible benchmark built with universities is not the same thing as a credible result announced by one company, alone, one week later.*

The HAWK-256 and AES-128 results were published by **Anthropic** through its own research blog, without the **co-authorship** of the external academic institutions involved in CryptanalysisBench, a distinction that matters for assessing the actual level of **independent scrutiny** each claim has received.

## What "AI discovers a cryptographic weakness" actually means here

### Discovery assisted by a model, not a fully autonomous breakthrough narrative

Anthropic's framing emphasizes that its **Claude Mythos Preview** model derived these results, a claim that fits a broader **industry narrative** about AI systems approaching or exceeding **human capability** in specialized technical domains. **This framing** deserves scrutiny distinct from the technical claims themselves: the degree of **human guidance**, prompt engineering, and iterative correction involved in reaching these results is not fully detailed in the **public materials** available.

Distinguishing between an **AI model producing a result under close human direction** and an **AI model autonomously discovering a novel technique with minimal guidance** is a meaningful **technical distinction** that the available sources do not fully resolve.

### Why this distinction matters for how the claim should be read

If the **attacks** required extensive human cryptographic expertise to guide, verify, and refine the model's output, the achievement, while still potentially significant, represents a different **category of result** than a claim of **autonomous discovery**. *Whether Claude found this alone or with a research team correcting every wrong turn changes what the result actually proves about AI capability.*

Anthropic's **published materials** describe the model's role prominently, but the available sources for this analysis do not include a full **methodological breakdown** of the human-AI division of labor in reaching the published results.

## The status of Anthropic's own safety framing

### A company stating its own result poses no immediate risk

Anthropic's own characterization that neither result **affects current production systems** is, itself, a claim made by the same **organization** that produced and is publicizing the underlying research. **This is not, on its own, a reason for suspicion** — companies with **cryptography expertise** routinely make accurate technical assessments of their own findings — but it is a detail worth naming plainly rather than treating as a neutral third-party judgment.

An **independent cryptographic audit**, separate from Anthropic's own **safety assessment**, would be needed to fully confirm that the **practical implications** described match the technical reality of the published attacks.

### Why self-assessed safety claims deserve the same scrutiny as capability claims

The same standard of **verification** that applies to Anthropic's capability claim — that its model found these weaknesses — should also apply to its safety claim — that the weaknesses found do not matter in practice. *A company grading its own homework as both a breakthrough and harmless is making two claims, not one, and both deserve to be checked.*

Neither claim is inherently **implausible**, but neither has, as of this analysis, received the kind of **independent academic scrutiny** that would settle the **question** definitively.

## What independent cryptographers would need to confirm this

### The minimum conditions for full verification

Full independent verification of Anthropic's claims would require outside **cryptography researchers** to run the **published implementation** themselves, confirm the claimed **runtime** and work-factor reductions on **independent hardware**, and publish their own findings through a peer-reviewed or otherwise scrutinized channel. **None of these three steps** is documented as having occurred in the sources available for this analysis, as of July 29, 2026.

The **NIST** standardization process itself, given its institutional pace, is unlikely to issue a **formal reassessment** of HAWK's candidacy status within days of a single company's announcement, regardless of that announcement's **technical merit**.

### A dossier that remains open, not resolved

This analysis does not conclude that Anthropic's claims are false, exaggerated, or fabricated: the published implementation and detailed **technical parameters** suggest a **genuine research effort** with real substance behind it. *Publishing your work is not the same as having it checked. Anthropic has done the first. Nobody outside the company has yet done the second.*

What this analysis does conclude is that the claims remain, as of publication, **unconfirmed by an independent third party**, a status that differs meaningfully from either "false" or "definitively proven."

## Why this matters beyond one company's research blog

### The stakes of AI-assisted cryptanalysis for global infrastructure

Post-quantum cryptography standards like **HAWK** are being developed precisely to protect digital infrastructure against future quantum-computing threats; any credible demonstration that AI models can accelerate attacks against **standardization candidates** carries real stakes for the security of systems still years away from deployment. **This context** explains why Anthropic's claims, even unconfirmed, deserve serious attention rather than dismissal.

At the same time, the stakes involved are precisely why **premature certainty**, in either direction — treating the claim as a **confirmed crisis** or dismissing it outright — would be a disservice to the seriousness of the underlying question.

### What this means for the NIST standardization timeline

If independent researchers eventually confirm Anthropic's HAWK-256 result, it could influence how **NIST** and the broader cryptographic community weigh HAWK's candidacy relative to competing **post-quantum schemes** still under consideration. *A standard's fate should rest on confirmed mathematics, not on the publication date of a single company's blog post.*

Until such confirmation arrives, treating the claim as a settled input into that standardization decision would be premature, regardless of how detailed Anthropic's **published materials** appear.

## How this fits Anthropic's broader public narrative on AI capability

### A pattern of publishing capability milestones

This announcement follows a broader pattern in which **Anthropic** and its competitors regularly publish research highlighting their models' growing capabilities in specialized technical domains, from coding to, now, **cryptanalysis**. **This pattern** serves both genuine scientific interest and a clear commercial incentive: demonstrating **frontier capability** strengthens a company's competitive position in the AI market.

Recognizing this **commercial context** does not invalidate the underlying research, but it is a relevant factor in understanding why capability announcements of this kind tend to receive rapid, wide media pickup before independent verification catches up.

### Why the pace of announcement outstrips the pace of verification

The **gap** between when a capability claim is published and when independent verification can realistically confirm or refute it is structurally longer than the news cycle covering the initial announcement, a dynamic already observed across multiple recent **AI capability claims**. *The claim travels at the speed of a press release. The proof travels at the speed of peer review. They rarely arrive together.*

This structural gap is not unique to Anthropic or to cryptography; it characterizes how **capability claims** across the entire AI industry are currently disseminated and, much more slowly, verified.

## What responsible coverage of this claim requires

### Naming the claim precisely, without inflating or deflating it

Responsible coverage of Anthropic's announcement requires stating precisely what was claimed — a reduced work factor for HAWK-256, a speedup against reduced-round AES-128 — without inflating this into "AI breaks encryption," a framing that misrepresents both the scope and the current **verification status** of the results. **This precision** is not pedantry; it is the difference between informing the public and needlessly alarming it about the security of systems the claim does not actually threaten.

Equally, dismissing the claim entirely because it originates from a company with commercial interests in demonstrating AI capability would be its own form of imprecision, given the genuine **technical detail** Anthropic did publish.

### What this analysis recommends to readers

Readers should treat Anthropic's HAWK-256 and AES-128 results as **credible but unconfirmed research claims**, worth following as the **story develops**, but not yet a basis for concluding that any currently deployed cryptographic system is at risk. *A claim worth watching is not the same as a claim worth believing. This one, for now, sits in the first category only.*

This analysis will need to be revisited if **independent cryptographers** publish their own confirmation, refutation, or qualification of Anthropic's published implementation and claimed results.

## What history of AI capability claims suggests about the likely outcome

### A mixed track record across the industry

Previous AI capability claims across the industry, in domains ranging from mathematical proof discovery to software vulnerability detection, have shown a mixed pattern upon **independent verification**: some held up largely as described, others required significant qualification once outside researchers examined them closely. **This mixed history** provides no **strong prior** in either direction for how Anthropic's cryptanalysis claims will ultimately fare under scrutiny.

What this history does suggest is that **patience**, rather than immediate acceptance or immediate dismissal, has historically proven the more **accurate posture** for this category of claim.

### Why this specific claim may attract faster scrutiny than most

Because **cryptography** is a field with an unusually active, technically rigorous community of independent researchers accustomed to publicly checking extraordinary claims, Anthropic's HAWK-256 and AES-128 results may receive faster independent attention than capability claims in less tightly scrutinized **technical domains**. *If any AI capability claim gets checked quickly, cryptography's community is exactly the one built to do it.*

This relatively fast-moving scrutiny culture in cryptography research is a reason for **cautious optimism** that this dossier will not remain unresolved for long, even if it remains unresolved as of this publication.

## What remains genuinely uncertain

### The open questions this analysis cannot resolve

This analysis cannot determine, based on currently available sources, the precise degree of human guidance involved in reaching Anthropic's published results, whether **independent researchers** have privately begun attempting reproduction, or how NIST will eventually factor this claim, if confirmed, into its standardization deliberations. **These three open questions** define the genuine limits of what can be said with **confidence** today.

Any claim to have **definitively settled** these questions, in either direction, would exceed what the currently available **public record** supports.

### What would change this analysis's conclusions

Independent confirmation of the claimed work-factor reductions, an official NIST statement addressing the HAWK candidacy in light of Anthropic's claims, or a detailed **methodological disclosure** clarifying the human-AI division of labor involved would each meaningfully update the conclusions of this analysis. *This dossier is not closed. It is dated, and it is waiting for exactly the kind of proof that only time and outside scrutiny can supply.*

Until any of these developments occurs, the most accurate description of Anthropic's claim remains: **detailed, published, and not yet independently confirmed.**

## What this episode adds to the broader AI-safety conversation

### A concrete data point in an often abstract debate

Much of the public conversation about advanced AI capability and safety operates at a fairly abstract, speculative level; Anthropic's **cryptanalysis claim**, whatever its ultimate verification status, offers a concrete, technically specific **data point** that researchers can actually attempt to reproduce or refute. **This concreteness** is itself valuable, regardless of how the verification ultimately resolves.

Debates about AI capability too often rest on **hypothetical scenarios** rather than testable claims; this dossier, precisely because it invites **independent verification**, represents a more productive form of that broader conversation.

### Why the industry needs more of this kind of testable claim, not fewer

Regardless of how Anthropic's specific results hold up, the practice of publishing detailed, **reproducible implementations** alongside capability claims should be encouraged across the AI industry, precisely because it is what makes independent verification possible in the **first place**. *A claim you can actually test is worth more than ten claims you are simply asked to believe.*

This standard of **reproducibility**, even when it leaves a claim's ultimate validity temporarily unresolved, is preferable to capability announcements that offer no path to **independent verification** at all.

Anthropic's claim that its **Claude Mythos Preview** model found a significant weakening of **HAWK-256**, a NIST post-quantum standardization candidate, along with an accelerated attack against a reduced version of **AES-128**, rests on published, detailed technical materials that permit, at least in principle, independent verification. As of **July 29, 2026**, no publicly documented independent confirmation of either result exists, and NIST has issued no formal reaction.

Anthropic's own assessment that **neither result threatens current production systems** is plausible on its technical merits but remains, itself, a claim from the same party announcing the underlying discovery. **The distinction** between a detailed, reproducible research claim and an independently confirmed scientific result is the central fact this analysis insists on preserving. *A published paper is an invitation to verify, not a substitute for the verification itself. Cryptography, of all fields, should be the last to forget that.*

This dossier will need to be revisited as **independent researchers**, and eventually NIST itself, respond to Anthropic's published implementation. Until then, the most accurate description remains that of a serious, well-documented, but **unconfirmed** claim — neither dismissed nor accepted, simply still open.

**By Maxime Marquette, columnist**

## Columnist's transparency note

### Editorial stance

I am not a journalist but a **columnist and analyst**. My expertise lies in observing and analysing the geopolitical, economic and strategic dynamics that shape our world. My work is to take political strategies apart, to understand global economic movements, to put the decisions of international actors in context and to offer analytical perspectives on the changes that are redefining our societies.

I do not claim the cold objectivity of traditional journalism, which stops at reporting facts. **I claim analytical clarity**, rigorous interpretation and a deep understanding of the complex issues that concern us all. My role is to give meaning to the facts, to place them in their historical and strategic context, and to offer a critical reading of events.

### Method and sources

This text keeps the basic distinction between **verified facts and interpretive analysis**. The rule never changes: a factual claim is published only when a verifiable source supports it, and the sources this article actually used are listed under **Sources**, never here.

**Primary source families** used by the publication, when the story has them: official statements from governments and international institutions, public statements by political leaders, reports from intergovernmental organisations, dispatches from recognised international news agencies.

**Secondary source families**: specialised publications, internationally recognised news media, analyses from established research institutions, reports from industry organisations.

When an article cites statistical, economic or geopolitical data, it comes from the institutions that produce it (intergovernmental organisations, central banks, national statistics offices), and the exact institution is named under **Sources**.

### Nature of the analysis

The analyses, interpretations and perspectives in the analytical sections of this article are a **critical, contextual synthesis** based on the information available, the trends observed and the expert comments cited in the sources consulted.

My role is to interpret these facts, to set them in the context of today's geopolitical and economic dynamics, and to give them a coherent meaning within the larger story of the changes shaping our time. These analyses reflect expertise built through continuous observation of international affairs and an understanding of the strategic mechanisms that drive global actors.

This article describes a documented state of affairs on its publication date, not a prediction: later developments may shift its outlook. No update is promised in advance; when an article is corrected or completed, the change is dated in the text.

## Sources

### Primary sources

- [The Hacker News, coverage of Anthropic's post-quantum cryptanalysis claim — July 29, 2026](https://thehackernews.com/2026/07/claude-ai-just-cracked-post-quantum.html)

- [Anthropic, research publication on discovering cryptographic weaknesses](https://www.anthropic.com/research/discovering-cryptographic-weaknesses)

- [AI TLDR, summary of Anthropic's Mythos cryptographic weaknesses research](https://ai-tldr.dev/releases/anthropic-mythos-cryptographic-weaknesses/)

### Secondary sources

- [Tech Times, coverage of the AI-assisted post-quantum cipher research — July 28, 2026](https://www.techtimes.com/articles/321876/20260728/ai-cracks-post-quantum-cipher-60-hours-after-two-years-human-review-failed.htm)

- [AI Weekly, alert on Claude Mythos's HAWK and AES findings](https://aiweekly.co/alerts/anthropic-says-claude-mythos-found-hawk-7-round-aes-flaws)

- [Brave New Coin, analysis of the Mythos post-quantum cipher weakening](https://bravenewcoin.com/insights/mythos-weakened-a-post-quantum-cipher-for-100000)

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Source: Maxime Marquette, MadMax. When citing, name the author and link https://mad-max.co/en/article/analysis-anthropic-says-it-advanced-post-quantum-cryptanalysis-and-no-one-has-ch