GoKawiilResearchers cut computational cost of breaking textbook RSA encryption
Researchers from UC San Diego and Inria Nancy have published a paper describing a new attack that significantly reduces the number of operations needed to factor RSA keys used in the 'textbook' or 'raw' RSA variant. For 1024-bit keys, the required calculations drop from roughly 2^80 to 2^65, with similar reductions across 2048-, 3072-, and 4096-bit key lengths. The findings have not yet completed peer review.
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If confirmed, the reduced computational threshold could bring 1024-bit key cracking within reach of well-resourced actors such as state intelligence agencies, according to the paper's implications. The authors note their algorithms are unoptimized, suggesting further speedups—potentially aided by GPUs or AI tools—could be possible, though this remains speculative pending review. The affected 'textbook' RSA variant is narrower than standard implementations but is still used in services like Cloudflare Privacy Pass, iCloud Private Relay, and Private Cloud Compute.
- A new attack reduces the operations needed to factor textbook RSA keys, e.g., from 2^80 to 2^65 for 1024-bit keys.
- The attack targets only the 'raw' RSA variant, used in select services rather than common website certificates.
- The research has not yet passed peer review, and the authors say their methods could potentially be further optimized.
Source: tomshardware.com — Bruno Ferreira, 2026-09-26
Published there as: “Novel attack slashes computing power needed to crack textbook RSA cryptography”
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