RSA-896 Has Been Factored. Steve Weis Reports Factoring RSA-896 Using Claude

RSA keeps getting factored. The question is what each new result tells us about the security of the encryption we still use: will the common standard of RSA-2048 be compromised soon, either with classical methods using CPUs and GPUs or rather with quantum and QPUs?

In our earlier article, RSA-260 Has Been Cracked… Apparently, we looked at the reported factoring of a 260-digit RSA challenge number. Now, Steve Weis has reported factoring RSA-896, using Claude to help adapt CADO-NFS for GPUs and orchestrate the computation across Anthropic’s infrastructure. Earlier in September, Eric Lu of Cognition reported factoring RSA-260 using Devin, the company’s AI coding agent.

The compute scale is striking: up to 2,048 GPUs, about 10 days of computation, and around 30 GPU-years of aggregate processing time.

Weis is clear about what the result does and does not show. It does not meaningfully improve the GNFS (General number field sieve) algorithm, and it does not compromise deployed RSA-2048 keys. However, he argues that RSA-1024 keys are vulnerable to organisations with data-centre-scale GPU resources.

Who Is Steve Weis?

Steve Weis is a software engineer and cryptography specialist who currently works as a member of technical staff on Anthropic’s Secure Frameworks team. His career spans cryptography, security, privacy and machine learning, with previous roles at Databricks, Facebook and Google. He co-founded PrivateCore, a security startup Facebook acquired in 2014, and has contributed to projects involving data privacy, Facebook Messenger security, PGP, and Google’s two-step verification. Weis holds a PhD in computer science from MIT, where RSA co-inventor Ronald Rivest advised him.

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