On October 24, 2024, the National Institute of Standards and Technology (NIST) announced that they’re advancing fourteen post-quantum signature schemes to the second round of the “signatures on ramp” competition. “Post-quantum” means that these algorithms are designed to resist the attack of quantum computers. NIST already standardized four post-quantum signature schemes (ML-DSA, SLH-DSA, XMSS, and […]
Tag Archives: cryptography
No, AI did not break post-quantum cryptography
News coverage of a recent paper caused a bit of a stir with this headline: “AI Helps Crack NIST-Recommended Post-Quantum Encryption Algorithm”. The news article claimed that Kyber, the encryption algorithm in question, which we have deployed world-wide, had been “broken.” Even more dramatically, the news article claimed that “the revolutionary aspect of the research […]
Inside Geo Key Manager v2: re-imagining access control for distributed systems
In December 2022 we announced the closed beta of the new version of Geo Key Manager. Geo Key Manager v2 (GeoV2) is the next step in our journey to provide customers with a secure and flexible way to control the distribution of their private keys by geographic location. Our original system, Geo Key Manager v1, […]
LavaRand in Production: The Nitty-Gritty Technical Details
Introduction Lava lamps in the Cloudflare lobby Courtesy of @mahtin As some of you may know, there’s a wall of lava lamps in the lobby of our San Francisco office that we use for cryptography. In this post, we’re going to explore how that works in technical detail. This post assumes a technical background. For […]
Introducing Zero Round Trip Time Resumption (0-RTT)
Cloudflare’s mission is to help build a faster and more secure Internet. Over the last several years, the Internet Engineering Task Force (IETF) has been working on a new version of TLS, the protocol that powers the secure web. Last September, Cloudflare was the first service provider to enable people to use this new version […]
How we built Origin CA: Web Crypto
At CloudFlare we strive to combine features that are simple, secure, and backed by solid technology. The Origin CA is a great example of this. You no longer need to go to a third-party certificate authority to protect the connection between CloudFlare and your origin server. You can now get a certificate to encrypt the […]
Yet Another Padding Oracle in OpenSSL CBC Ciphersuites
Yesterday a new vulnerability has been announced in OpenSSL/LibreSSL. A padding oracle in CBC mode decryption, to be precise. Just like Lucky13. Actually, it’s in the code that fixes Lucky13. It was found by Juraj Somorovsky using a tool he developed called TLS-Attacker. Like in the “old days”, it has no name except CVE-2016-2107. (I […]
How to build your own public key infrastructure
A major part of securing a network as geographically diverse as CloudFlare’s is protecting data as it travels between datacenters. Customer data and logs are important to protect but so is all the control data that our applications use to communicate with each other. For example, our application servers need to securely communicate with our […]
Logjam: the latest TLS vulnerability explained
Yesterday, a group from INRIA, Microsoft Research, Johns Hopkins, the University of Michigan, and the University of Pennsylvania published a deep analysis of the Diffie-Hellman algorithm as used in TLS and other protocols. This analysis included a novel downgrade attack against the TLS protocol itself called Logjam, which exploits EXPORT cryptography (just like FREAK). First, […]
Why some cryptographic keys are much smaller than others
If you connect to CloudFlare’s web site using HTTPS the connection will be secured using one of the many encryption schemes supported by SSL/TLS. When I connect using Chrome I get an RC4_128 connection (with a 128-bit key) which used the ECDHE_RSA key exchange mechanism (with a 2,048-bit key) to set the connection up. If […]
