1. The TLS handshake involves a step to discover the commonly supported algorithms and can incur additional roundtrip if the first guess does not works out, its part of the protocol to keep it stateless
2. Cloudflare is scanning all the origins on daily basis and storing the result for supported algorithms to save on the possible roundtrip time
Whats missing in the article - They are saving on the *possible roundtrip latency, however they are not sharing the absolute lookup latency which now gets added to every connection
If the new for-every-request latency is noticeable above the noise floor at all then they could be really tricksy and make two connection attempts, one immediately with the default guess and one with the looked up value, and as soon as the first connection succeeds abandon the other. In fact if the majority of the connections needing a retry use the same method, so there are two covering almost all cases, you could remove the lookup and just send out two connection attempts, one with each of those two methods. I very much doubt this would be worth the effort, and it would add load elsewhere that would need to be accounted for in judging the value of the optimisation.
Specifically TLS 1.3.
They don't explain, but late in TLS 1.3 development it was discovered that if you just say you're talking TLS 1.3 by increasing the version byte in the packet, as the protocol was designed almost thirty years ago, crap "security" middleboxes at a significant number of sites freak out and nothing works. Deploying a protocol which just doesn't work for, say, 10% of systems is unacceptable.
So the way TLS 1.3 actually works is - you begin the conversation pretending to be a TLS 1.2 client resuming an earlier conversation. You pick an arbitrary random long ID for this non-existent conversation, and you say you also happen to know a TLS 1.2 extension, and that bogus "extension" is actually your entire TLS 1.3 connection setup.
If the server you reached also knows TLS 1.3 they understand this charade, they reply "accepting" the resumption and since a TLS 1.2 resumption would just be encrypted application data, all TLS 1.3 just has the rest of the conversation labelled as TLS 1.2 application data and the dumb "security" middleboxes won't molest it. Nothing to see here.
If it does not know TLS 1.3 then this made-up ID won't match an actual conversation it has ever had, it can't resume that conversation, how about a new connection using the older protocol version, and everything proceeds as usual for the older protocol.
The insight in TLS 1.3 was that we can guess a KEX and if we're correct we win a free roundtrip overhead†. So the history is that in TLS 1.2 you will always eat two round trips to talk HTTPS the first time, though in some cases you can reduce it to only one to "resume" conversations, in TLS 1.3 you can spend only one round trip even the first time if you guess the right KEX, and as few as zero round trips in some specific cases.
† This also means there's a strong incentive to have few KEX options, a new KEX must be unarguably better for a large constituency so that it's worth losing the round trip bonus to get a better KEX until your KEX is so popular that everybody will guess that KEX instead of the previous most popular.
1) So they saved 15ms on the connection so that you can then wait 20s in their annoying nag screen before reaching the real website content.
2) On the Monday they complain about the load on server by LLM scrapings compulsively your webserver an offer themselves as the internet guardian solution; and on Tuesday, they compulsively send useless requests to your servers so that they can save a few microseconds in the very first connection ever to your server. "For each TLS 1.3 capable origin, we run a series of a few lightweight TLS handshakes, each offering exactly one key agreement group: X25519, P-256, P-384, P-521, or X25519MLKEM768. [...] And because the active scanning happens outside your production traffic path, we confirm that both your origin and the network in between can handle connections with a stronger key agreement before any real traffic depends on it.
I'm so tired of having to do Captchas and waiting everywhere to access websites
This is a hobby for me. It’s for my enjoyment and it allows me to provide resources that others enjoy using. However, I’m not going to allow literally 99%+ of requests to be aggressive scrapers that won’t give up until you’ve got a heavy-handed solution in place.
I hate it too, but the alternative is even more consolidation, so unfortunately this is just the reality right now and you’ll have to get over it until when/if things improve.
No, the actual alternative is learning to do it yourself. Unless you're a frequent target of UDP DDoS, there is almost nothing you can't defend against straight from the server itself.
Spending time learning how to configure your firewall, set rate limits in your web server, tune your application for caching and further rate limits, and should all this fail install a self-hosted captcha/proof-of-work fence yourself, is definitely a fair amount of efforts when those things aren't part of the core hobby.
Rate limiting doesn’t work when individual IPs are only making a handful of requests.
So that’s why we’re using CF/Fastly. Too bad, I’d prefer not to, but there is just not an alternative at this point.
Those requests aren't useless; They clearly optimize. What a silly take.
>to your servers
To their customer's servers, right! Most people turn on other CF optimizations like h2/h3 to origin.
If you work at a SaaS of any kind, I think it's worthwhile considering what things will look like when scale is the only thing that is really defensible anymore.
the obstacle was always the parade of tedious obstacles to create (in this case) a sophisticated virtual harness to simulate (in this case) whatever the hell this article is about. so yeah, actually, the capability of retail coding plans are kind of the only thing that matters...
I think things like this are now possible through vibecoding.
Those who are above the bar can steer and add their expertise to hit a new level.
Tracking you by monitoring the network traffic between CF (or other connection aggregator) and the origins is possible, but usually significantly more effort. Those with reason to be concerned about true end-to-end encryption will know that seeing any CF artefacts means they need to investigate to know if they are getting e2ee or just end-to-proxy.
• consistent • not overly serious, so users who end up trained to ignore this new signal don't automatically ignore more significant warnings • (and this is the fun part) communicate this new semaphore signal to the general public without confusing them…
To head off one cynical question: “Why worry about the general public when they wouldn't care anyway and just click through warnings with wreckless abandon already?” - if not the general public then who would this be for? Those who might need to care are already checking if their data is going through CF and so might not to under true E2EE.
cf-http-endpoint: 1
cf-encryption-mode: off/flexible/full/full-strict/strict