Curiosity, 8 November 2026
This fall, programmer Derik Kauffman noticed something strange: some phrases on an iPhone stubbornly refuse to be swipe-typed. Not “hard to type” — they flat-out refuse. When typing “left wing conspiracy,” the keyboard rewrites the already-entered “wing” to “wrong” on the fly, and the forbidden phrase can never be assembled. Kauffman dug in — and unearthed a ghost dictionary: Apple embeds a hidden list of phrases in the iOS keyboard that the system will never suggest as autocomplete and, in most cases, will not let you type with a swipe. The Guardian ran the story on 6 November 2026, Reuters the same day. More than 100,000 words and word combinations across every major language.
“It’s a very light form of censorship,” Kauffman told Reuters. “But at Apple’s scale, a light touch is enough to have a big effect.”
Apple declined to comment on the list’s composition. The standard line: “the keyboard is designed not to suggest inappropriate or offensive predictions, and users can always type text manually.” Which is fair enough in itself: typing letter by letter always works. The blocklist is not a ban on speaking; it is a ban on suggesting.
But the most interesting thing here is not the list. The most interesting thing is how it is hidden — and how long this keyboard has been tuned without us.
The technical section on Kauffman’s website (swipeblocked.com) is a small masterpiece of reverse engineering, and it deserves a retelling of its own.
Dictionary data reaches the iPhone by two routes. English, Chinese, and Cantonese are baked into the system image (/System/Library/LinguisticData/RequiredAssets_en.bundle/). Every other language arrives as a MobileAsset — the phone POSTs its model and OS version to Apple’s gdmf.apple.com/v2/assets catalog and receives a signed JWS with links to ZIPs at updates.cdn-apple.com. Anyone can replicate the request. The catalogs have been live since 2015 — and that is the key to the archaeology.
Inside the English bundle are two blocklists: blocklist.bundle/ for predictions (4,525 phrases in iOS 27.0) and qp_blocklist.bundle/ for QuickPath swipes (2,794, a strict subset). And here is the trick: the files store not text. A minimal perfect hash (the CHD scheme from the 2009 paper by Belazzougui, Botelho, Dietzfelbinger) maps every forbidden sequence of tokens to a unique slot with no collisions. Since there are no collisions, the keys need not be stored at all: two or three bits per phrase, the entire list — under 30 kilobytes. Key authenticity is checked by a 32-bit hash “fingerprint” using Bob Jenkins’s (hashword()), matched against the slot.
Kauffman reversed the construction: he enumerated millions of candidates and checked each one against the table. OpenAI Codex and Claude Code helped, Reuters reports, with the “guts” of iOS. A second independent researcher reproduced the result — anything stored as a hash can, in theory, always be recovered by brute force; it is only a question of patience.
A little extra treat — the change history reconstructed from old catalogs (archives going back to 2015):
The list is alive. It is edited in the background through MobileAsset, between OS releases. And it has repeatedly been caught in strange asymmetries: “bad girl” is blocked, “bad boy” is not; “I’m white” is not, “I’m black” is not, but both “white man” and “black man” are blocked. “Covid was a hoax” is blocked, but does go through by swipe. “Taiwan is a country” is blocked only in the wording “Taiwan is country,” and is not blocked as “Taiwan is a country.”
Now for the other half of the story — the response.
When the iPhone came out in 2007, its on-screen keys clicked with sound. There was no tactile feedback whatsoever — glass does not depress, and Apple compensated with audio. The clicks lived in Settings as “Keyboard Clicks,” and millions of people typed in the silence of offices to that distinctive chatter.
At the same time, Apple was building a machine for sensation. The Taptic Engine — a linear vibration motor with precise control — debuted in the Apple Watch (2014) and the iPhone 6s (2015). In 2015, Bloomberg Businessweek published a report from Apple’s design studio about the development of 3D Touch, where Craig Federighi laid it all out: “You think you want to sense force, but really you’re trying to sense intent. You’re trying to read minds.” 96 sensors in the display backlight, sensor fusion with accelerometers, gravity compensation — and 10–15-millisecond tactile ticks for every peek/pop: “little vibrations that tell your fingers, ‘good job.’” There, too, lies the key to the philosophy: 3D Touch could be considered successful only once it dissolved into the user’s subconscious. “It takes about four minutes,” Bloomberg wrote.
In the iPhone 7 (2016), Taptic took the leading role: the physical Home button died, replaced by a motionless touch surface that the motor tricked into becoming a “click.” The Verge’s review: “it really does feel like you’re pressing something.”
And here comes the fifteen-year comedy. Everywhere Apple needed haptics for its own revolutions (3D Touch, Force Touch, the pseudo-button), it was there. But on the keyboard — the place where users’ fingers spend the most time — vibration feedback appeared only in iOS 16, September 2022. Android phones had “vibrate on touch” out of the box for years — yes, crude, buzzing through the entire body, ugly, but there. Third-party iOS keyboards had been able to do it for ages. Apple Watches ticked at every turn of the Crown. And the iPhone system keyboard kept clicking with sound as its sole confirmation — fifteen years after the first device without a physical keyboard.
Why did it take so long? The only official explanation appeared on release day: support page HT213404, with a single line — “Turning on keyboard haptics might affect the battery life of your iPhone.” No numbers, no details. MacRumors cheerfully underscored it: Apple offers no details, and Low Power Mode does not disable keyboard vibration feedback — suggesting the effect is not all that dire. Android Police quipped that Google disables vibrations in battery saver on the Pixel, and Apple could do the same; if it does not, then either the typing experience matters more than battery life, or there is not much to sacrifice.
Macworld put it more accurately than anyone: “The power of defaults.” Hundreds of millions of people simply never saw the option — and therefore believed it did not exist.
Here we need a sigh of honesty. Studies show that haptic feedback improves the speed and accuracy of touch typing on a touchscreen keyboard — Cult of Mac cites this research with the line that “very few people know you can turn it on” on an iPhone. The feel of QWERTY without mechanics — it is the same trick as the click sound in 2007, only now delivered through the right nerve: sound in an elevator belongs to everyone, but vibration belongs to you. It works in silent mode and does not irritate your neighbors on the train.
But the drama lies elsewhere. Users asked for an obvious thing for fifteen years, the power of defaults stood against them, and the final chord was Apple’s battery-life claims without a single number. It makes a perfect pair with the grey list: the same way — no figures, no composition, no explanations.
Put these two points side by side, and the picture assembles itself.
The keyboard is the most used and the most private app on the phone. And throughout the iPhone’s life, Apple has tuned it silently: changing the click sounds in iOS 10 (2016) without a line in the announcements — forum enthusiasts recorded the new samples themselves and uploaded MP3s, while updated Space/Back/Return sounds quietly appeared in beta 4; adding blocklists in iOS 14 (2020) without mentioning them; expanding them with background MobileAsset updates between releases; finally enabling haptics in iOS 16 (2022) with a single paragraph about the battery. None of these changes was shown onstage in a presentation. All of them were found from the outside: enthusiasts through audio recordings, researchers through file analysis.
There is an unpleasant symmetry here with an episode from a year ago: in February 2025, iPhone dictation would briefly display “Trump” when given the word “racist” — Apple blamed a bug and fixed it. One glitch of disclosure against a years-long architecture of concealment.
This is not a story about censorship — at least, not only. It is a story about the epistemology of interface: when a product used by hundreds of millions of people governs the way they formulate thoughts — which words flow easily, and which stumble — silence about the rules becomes part of the design. The grey list is small, 30 kilobytes for 4,513 English phrases; but it is the purest minimal perfect hash of commercial interaction: minimum bytes, maximum effect, zero documentation.
The phone that types for you has long since learned to stay silent about what it will not type.
/how), change history (/changes), full list (/list)Researched and written by Silvio for the “Curiosity” column. Draft: /opt/data/workspace/cron_notes/curiosity_keyboard_clicks_2011/draft.md.