Take a leaf out of urbit's book, and convert hex strings into readable nonsense syllables that are a lot easier for humans to compare.
Maybe an auralizer to turn the hash into a short piece of music?
The point is to leverage human pattern matching so you want short-ish figures with large differences.
Each hex digits is 4 bits, but each emoji is 10 bits, a 128 bits key is 13 emoji which is significantly more eyeballable than 32 hex digits, and chances are you'll notice EGGPLANT being replaced by CAMERA in 13 pictures easier than you'd notice B being replaced by 8 in 32 characters.
Compare like with like - what are the two most similar emoji from that set of 2^10 ?
[0] https://en.wikipedia.org/wiki/Box_Drawing
[1] https://en.wikipedia.org/wiki/Mahjong_Tiles_(Unicode_block)
[2] https://en.wikipedia.org/wiki/Domino_Tiles
[3] https://en.wikipedia.org/wiki/Playing_cards_in_Unicode#Playi...
An example of urbit's rendering of a 128-bit number into textual form is "racmus-mollen-fallyt-linpex--watres-sibbur-modlux-rinmex". While it might be gibberish, it's gibberish that even a screen-reader program could take a swing at, and humans can easily read.
https://www.npmjs.com/package/proquint
Proquint (5 letters per 16 bits) is tighter than Urbit's `@p` (6 letters per 16 bits). The Urbit form was designed for synthetic names and restricts itself to phonemes that sound comfortable and natural to English speakers. (Not to say that English should be the universal language, it's actually a terrible language to make everyone learn, just that it is.)
Word lists work reasonably well, but they're quite bulky and they don't take advantage of the human hardware accelerator for learning new words. When you have a GPU, use it. These kinds of synthetic strings also make great passwords, BTW.
(Disclaimer: Urbit guy here.)
* Strict CV syllable scheme.
* Atonal
* Consonants distinguished only by voiced/voiceless (Chinese, e.g., doesn't do a voicing distinction, but switching to an aspiration distinction would suffice for them)
* 5 vowels: a, e, i, o, u (actual vowel quality may vary; every language that has at least 5 vowels has these 5 vowels) (some languages, particularly indigenous languages in North America, have 3 or 4 vowels, but the intersection yields too few vowels).
* Consonants are harder to inventory. /p/, /t/, /k/, /m/, /n/ are nearly universal, and /b/, /g/, /d/, /s/, /z/ are also quite common. The IPA /j/ (that's the 'y' in 'ya' for English speakers), /w/ (pronounced as you'd think in English) are pretty common semi-vowels. Maybe /l/, /ʃ/, /ʒ/ as well, should you need more consonants.
That gives you 25-75 plausible syllables, depending on how many consonants you go with.
[1] If you go by least common denominator, you end up with maybe 1 vowel and no consonants (there's no consonant phoneme present in every language IIRC).
Edit: not suggesting that Lojban's solution is somehow preferable to your advice, just trying to remember what they did about this issue.
From what I can tell, CV(C) (with the second consonant usually having some restrictions) is fairly widespread. However, in my personal (purely anecdotal) experience, pronouncing foreign consonant clusters or unfamiliar final consonants is much harder than pronouncing unfamiliar initial consonants or vowels, so I'd be slightly wary of letting the final consonant go too unrestricted.
Do Debian or any of the *BSDs yet default to including a font that supports emoji?