cryptography

A cryptography library had a bottleneck no test could see : encrypting half a megabyte took fifty seconds. Every test passed. They had been passing for months. The cause is a trap that keeps recurring: a correct, well-documented optimisation that fixes the constant and not the order — and whose comment, precisely because it is well written, convinces the reader the problem is already solved. What…

A researcher’s social media post revealing how to break part of a popular encryption protocol has gone viral. But did he really do it with just “good old pencil and paper”?

Eric Lu announced on X today that he has factored RSA-260, a number N with 260 digits (862 bits) that is the product of two large primes [1]. RSA numbers are challenge problems posed to gauge the security of RSA encryption, which rests on the difficulty of factoring large numbers [2]. The naming scheme is […] The post New RSA number factored first appeared on John D. Cook .

Quantum computers threaten widely used cryptography, like RSA and elliptic curve cryptography—essential for blockchains—by solving currently hard problems.

Blockchain encryption protocols are facing their first real stress test since Bitcoin's launch in 2009. For over a decade, the cryptographic assumptions underpinning nearly every major chain—elliptic curve signatures, SHA-256 hashing, RSA key exchange—held steady because no adversary had the computing power to break them. That assumption is now expiring. Researchers estimate that a sufficiently p…

France’s 2022 e-vote, with over 524,000 ballots cast, revealed critical security flaws, prompting exploration of postquantum cryptography as a more robust alternative.

When a new cryptographic algorithm appears, a tension shows up: classical algorithms such as X25519 or Ed25519 have resisted attacks for years, but are vulnerable to a future quantum computer; post-quantum ones such as ML-KEM or ML-DSA resist quantum attacks, but are newer and less tested. Hybrid encryption resolves the tension: use both at once . The idea in one sentence Combine a classical and …