RSA-896 Factored Using Claude and GPU Cluster

RSA-896 Factored via GPU Orchestration

On September 19, 2026, the RSA-896 challenge number was successfully factored. The process was led by researcher madars, who utilized Claude to port the CADO-NFS (Number Field Sieve) implementation to GPUs and orchestrate the execution across a fleet of scavenged idle compute capacity.

Compute and Technical Execution

The factorization was achieved using a massive parallelization of existing algorithms rather than a mathematical breakthrough. The technical specifications of the run include:

• Hardware: A maximum of 2,048 GPUs.
• Duration: 10 days of wall-clock time.
• Total Compute: Approximately 30 GPU-years.
• Software: A GPU-ported version of CADO-NFS, orchestrated by Claude.

Impact on Cryptographic Security

This achievement does not represent a new threat to currently deployed RSA keys. The author explicitly clarified that there were no new algorithmic factoring improvements and that the complexity of the problem remains exponential. The success of the project is attributed to the scale of available compute and the efficiency of the Number Field Sieve (NFS) algorithm developed over several decades.

Analysis and Community Discussion

Following the announcement, technical discussions centered on the role of AI in the process and the availability of idle data center capacity.

The Role of AI vs. Compute Some observers noted that the AI's contribution was primarily in the engineering phase—porting code and orchestrating the cluster—rather than solving the mathematical problem itself. As one commenter noted:

"You don’t need AI to solve this. Just lots of compute."

Resource Utilization Discussion emerged regarding the use of 2,048 GPUs for a mathematical puzzle. While some viewed this as an inefficient use of resources, others argued that utilizing scavenged idle capacity is effectively free if the hardware is already paid for and reserved.

Practical Implications for Legacy Keys The factorization of RSA-896 highlights the vulnerability of shorter RSA keys. Community members pointed out that some services, such as Instagram, continue to use 768-bit RSA DKIM keys, suggesting that such keys could now be factored as a relatively short-term GPU project.