RSA-260 Factorized by User 'penlu' on X
Original: RSA-260 Factorized
Why This Matters
Factoring RSA-260 would be a landmark cryptographic event with direct implications for RSA encryption security.
On September 3, 2026, X user 'penlu' posted a 126-digit prime factor of RSA-260, a 260-digit semiprime from RSA Security's factoring challenge. The post garnered 15.7 million views, with notable replies from cryptographer Alec Muffett and Elon Musk.
On September 3, 2026, at 4:45 AM, X user penlu (@penlume) posted that the 126-digit number 4397328654844826923795068102505872571721883526553349659561256924505973939597593482272505698004801207988043088656411102133523080581 divides RSA-260, a well-known challenge number from RSA Security's RSA Factoring Challenge. RSA-260 is a 260-digit (864-bit) semiprime, meaning it is the product of exactly two large prime numbers. Successfully identifying one prime factor effectively breaks the number. The post received 15.7 million views and generated significant attention in the cryptography and security communities. Cryptographer Alec Muffett replied, 'Hello from RSA-155, and congratulations,' referencing the earlier RSA-155 factorization milestone. Elon Musk also commented, 'Good thing we increased the character limit,' noting the factor itself is too long for the original 140-character tweet limit. No independent verification or formal publication details were included in the original post.