Unsound Advice

LLM garbage

Fri, 28 Aug 2026 22:19:32 +0000

Domain change

Thu, 11 Jun 2026 14:48:30 +0000

Transferring the old domain (joat.me) to my new Canadian registrar was too expensive (well... for me) so I've moved this blog to a new domain, joatie.ca. The old domain will continue to work until December but in the unlikely event that you have any bookmarks or links to here please update them.

Can you put an encrypted LUKS partition on a floppy disk?

Sun, 21 Sep 2025 22:17:20 +0000

TL;DR yes you can. The below is probably not optimal but it was the best I could do with an hour of messing around.

All this was done using a USB floppy drive. Here's what a regular floppy with a DOS filesystem (as they usually came already formatted) looks like:

% sudo mount /dev/sda /mnt
% df /mnt   
Filesystem     1K-blocks  Used Available Use% Mounted on
/dev/sda            1424     0      1424   0% /mnt

So let's unmount it first:

% sudo umount /mnt

Make the LUKS partition in the normal way but tune some parameters to get more available space. This gives a header that supports only one passphrase:

% sudo cryptsetup luksFormat --sector-size 512 --luks2-keyslots-size 256k --offset 568 /dev/sda
WARNING: Device /dev/sda already contains a 'vfat' superblock signature.

WARNING!
========
This will overwrite data on /dev/sda irrevocably.

Are you sure? (Type 'yes' in capital letters): YES
Enter passphrase for /dev/sda: 
Verify passphrase: 
WARNING: LUKS2 keyslots area size changed to 258048 bytes.
WARNING: keyslots area (258048 bytes) is very small, available LUKS2 keyslot count is very limited.

Open it so we can build a filesystem:

% sudo cryptsetup open /dev/sda cryptfloppy
Enter passphrase for /dev/sda:

Let's make a DOS filesystem and mount it; there's no point using a better filesystem on such a small device:

% sudo mkdosfs /dev/mapper/cryptfloppy 
mkfs.fat 4.2 (2021-01-31)
% sudo mount /dev/mapper/cryptfloppy /mnt

And how much space do we have left? About 1.1 MB:

% df /mnt
Filesystem              1K-blocks  Used Available Use% Mounted on
/dev/mapper/cryptfloppy      1132     0      1132   0% /mnt

Things That Are Small Enough To Fit in a QR Code

Tue, 20 Aug 2024 14:56:44 +0000

Some things that, even after ASCII-armoured GPG encryption, are small enough to fit into QR codes that are readable as plain text:

two-factor authentication backup codes
SSH private keys (RSA ≤3072 bits or ED25519)
GPG private keys

These can then be carried around with you as a last-ditch backup. They could even be disguised in fake travel tickets, business cards, ad flyers, etc.

Use Cases

Hard-copy but still machine-readable backups of critical keys and codes
Temporarily remove secrets from devices that may be searched or imaged by border security
- Sub-case: link to copies of data elsewhere, for example, a link to a pastebin of an encrypted https://rclone.org/ config file, which can then be used to restore larger content from cloud storage

Example Generation

These commands are on Linux (and should thus work on WSL on Windows or at the Mac terminal). Here we are using an SSH private key but the file could be anything. Choose a strong password that you'll remember for the GPG stage.

gpg -ca <~/.ssh/id_ed25519 | gpg -ca | qrencode -o id_ed25519.png

Print the PNG file (or incorporate it into a disguise document) then securely discard all files after printing. One way of doing this is to disable swap and work entirely in /dev/shm to prevent the file from ever touching storage. One advantage of QR codes is that they are completely offline so why risk the file being found on your system?

Encrypt an SSH private key again even though it already has a passphrase to conceal the content type.

Carefully test the resulting codes after printing; many printers aren't as precise as computer displays.

Example Extraction

To read and extract the above example at the command line:

zbarcam | gpg >/dev/shm/id_ed25519

Extract the matching public key if needed:

ssh-keygen -y -f /dev/shm/id_ed25519 >/dev/shm/id_ed25519.pub

To extract on Android, scan with QR & Barcode Scanner then tap Share As Text and send it to the decrypt option of OpenKeychain.

To extract via GUI on Windows or Mac – I don't know, I don't use either. I'm sure tools exist though. To extract on iPhone – I also don't know but I bet it'll cost money.

Daily Free Word Games

Sat, 06 Jul 2024 01:55:47 +0000

New York Times Games Wordle, mini crossword, Strands, Connections, and others
Daily Maverick mini crossword
One Word Search search for a single word at a time in a grid (also links to Stackdown and Waffle)

Generating PIN Codes With a Calculator

Wed, 08 May 2024 23:14:37 +0000

PIN codes are most often used for bank cards and for unlocking phones. Remembering good codes is hard, so people choose a poor quality code that is easy to remember.

But what if you could have a good code with a way to recover if you forgot it? Choose a poor code then do some calculator math to make a good code. For the sake of example we'll choose a date. In real life this would probably be something like a birthday but we'll choose a historical date, the year of the first Moon landing, 1969. Pick a math function that you like, for example:

$$\begin{eqnarray} \sqrt{1969} &\approx& 44.373415 \\\ \log_{10}{1969} &\approx& 3.2942457 \\\ \end{eqnarray} $$ It's best to use at most 8 digits since that's the precision limit of the worst calculators but if you use fewer digits then they don't have to be the leading digits. If you forget the actual digits you only need to remember square root of the first Moon landing and worst case you can ask a kindly stranger to calculate it for you on their phone.

#passwords #security

Carbon Footprint of Refurbished PC Router

Tue, 23 Apr 2024 23:44:43 +0000

Considered relative to buying a new consumer router.

I recently replaced my old router with a mini-PC running OPNsense. Some back of the envelope calculations on carbon footprint, compared to buying a new consumer router.

Background data


Ontario electricity carbon intensity (2020 data)	0.025Kg/kWh
Carbon footprint of manufacturing a laptop	331Kg
...and transporting from country of manufacture to country of sale	30Kg
Carbon footprint of manufacturing and transporting a new consumer router (estimated at one tenth of a laptop)	36Kg
Carbon footprint of transporting and refurbishing a mini PC (estimated at one third of a new laptop)	10Kg
Measured power consumption of old router	70.7kWh/year
Measured power consumption of mini PC router	139.8kWh/year
Excess power consumption of mini PC	69.1kWh/year

If it is accepted that the carbon footprint of the refurbished PC is considered in light of the alternative, which is purchasing a new consumer router, then the manufacturing and transportation carbon footprint of the mini-PC is $$10-36=-26Kg$$

The extra carbon footprint per-year of running this router instead of a consumer router is $$0.025\times69.1\approx1.73kG$$so assuming no change in energy production the mini PC has lower carbon emissions if the service life is less than $$\frac{26}{1.73}\approx15 years$$

which seems very likely given modern electronics lifetimes.

Turning a Tiny Refurbished PC into a Home Router

Sun, 21 Apr 2024 01:39:52 +0000

I bought a refurbished off-lease Lenovo M93p for ~C$120 to replace my aging no-longer-supported router, as yet unaware of the horrors lurking within Lenovo BIOSes. TL;DR I got it working fine but should you buy one? No, but probably something similar. I'll explain at the end.

The Hardware

This is it, showing some signs of wear and tear (serial number obscured):

Core i5-4570T, 4G RAM, 500G disk. I replaced the disk with a 2TB spare I had on-hand (not because I need 2TB, just because I trust it more – I think it's the HDD that came with my PS4 which I replaced with an SSD). I ordered a Mini-PCIe ethernet card at C$25 from Amazon. While I waited for that to arrive I installed OPNsense.

The adapter arrived two days later (early!) in this terrifyingly generic box:

...and the actual device looks like this. It's a full-height card with perforations to snap it in half to fit into a half-height slot:

The top of the case slides off after removing this screw:

It looks like other screws were present in the past but have been lost. Also note the empty cutout above the VGA connector. That's where we'll put the ethernet jack.

The inside looks like this:

Removing the disk we can see the existing wireless adapter in the Mini-PCIe slot:

Removed the wireless card but left the antenna connector – no point leaving a hole and messing up the airflow:

This is a half-height slot so snapped off the extra part of the new card then installed in the slot:

The ethernet port at the other end of the ribbon cable fits perfectly into the cutout. No screws are supplied so you'll have to find your own:

Reinstall the hard drive:

And close the case to see the final product:

The Horror Of The BIOS

Turn it on and I receive the dreaded 1802 Unauthorized Network Card error and it refuses to boot. Lenovo, the disgusting, anti-competitive, money-grubbing scum that they are have a whitelist in the BIOS of acceptable cards for that slot. A web search shows that this is very common in Lenovo desktops and laptops and you should never buy one but that there might be some ways around it. In order of how drastic:

Use the AMIDEDOS.EXE or AMIDEWIN.EXE tools included in Lenovo's BIOS update tools to set the system serial number to INVALID.
Flash the BIOS and simultaneously set the system model and serial numbers to INVALID
Identify the ID of the new card and patch then flash the BIOS to make the new card acceptable.

I was lucky; option 1 worked for me. Once done it still beeps and complains about the invalid card but continues to boot in the “manufacturer boot order”. You can't control this order but since I had already installed OPNsense this just worked – it booted fine. And it's a router, it sits in a corner with no monitor so who cares if it complains? If I ever need to re-install I may need to disconnect the ethernet card before booting from USB but that's not a big deal.

The Result

The new card (described in the Amazon listing as “widely compatible”) is identified by FreeBSD as RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller so not ideal for OPNsense but seems to be working fine so far. So anyway I now have a working “Tiny Form Factor” OPNsense PC router with dual 1G ethernet at a much lower cost than most of the dedicated router PCs out there, and probably more performant. Here it is mounted on my network wallboard:

All of these tiny PCs have optional VESA mounting brackets but good luck finding one for an older model. However they are also very close to the thickness of a standard North-American 2×4 board (they are ≈1.4” or 36mm thick, a 2×4 is exactly 1.5” or 38mm thick) so there is a lot of hardware available in that size. I bought a pair of these “Open Gate Bar Holders”, and padded the inside with some stick-on felt furniture pads for a snug, scratchless fit.

Finally, here's a screenshot of the System information widget on the web dashboard:

Should I Do The Same?

But should you do the same? Yes and no.

Yes, build yourself an OPNsense router. They have a lot of features you won't get in a regular home router. It's fun to play with them. The active queue management works really well – fiddly to configure but there are a lot of tutorials and it definitely gets rid of a lot of lag on your network, especially slow downloads when somebody is on a video call.

If you want more peace of mind, buy one of the dedicated PC router appliances like the Protectli Vault 2-port. You'll get all-Intel NICS which OPNsense prefers. However even the old Core i5 in the old mini PC that I bought outperforms the CPUs in the new appliances (usually something like a J3710 or N5105) by a substantial margin at a much lower cost.

But no, don't get a Lenovo unless it's really cheap and you have the opportunity to return it if you can't defeat the BIOS. (Also, your time has value so don't even do that unless you want to waste time fiddling with it.). If you have more space than I have on my network board above then get a bigger PC; even “Small Form Factor” models have two half-height PCIe slots giving you more add-in network card options, and refurbished SFF units are usually cheaper than TFF units.

But if you still want a TFF PC, don't get an HP Elitedesk; they have an internal card slot but no cutout on the rear. Instead, get a refurbished Dell Optiplex. They are a little more expensive for the same specs but most of them have cutouts on the back and a card slot (M.2 instead of Mini PCIe so buy the correct card). More importantly, my searches suggest that they do not have the same card whitelist problem. And don't worry about specs too much; 4G of RAM is punishingly slow in a desktop but overkill for a home OPNsense router.

Some refurbished desktop PC sources:

Calculator Collection

Sat, 16 Dec 2023 00:47:14 +0000

Calculator collection table.

Make	Model	Batteries	Year	Notes
?	Personal Organiser	?
Canon	card FC-53	CR2032
Canon	Palmtronic 8ms	2×AAA		Case
Canon	MULTI 8	3×AAA		Case
Casio	fx-9750GA PLUS	4×AAA
Casio	fx-300ES PLUS	LR44
Casio	fx-300ES	LR44
Casio	FX-880P			Pocket Computer
Casio	fx-300MS	LR44
Casio	fx-115N	Solar
Casio	fx-82LB	2×		Faint display, cover missing
Casio	memory-8R	2×AA		Case
Casio	fx-991W	LR44
Casio	fx-991MS	LR44
Casio	fx-CG50	4×AAA
Casio	SF-5580	2×AAA CR2032		(Organiser) box, manual
Casio	fx-7000GA	3×CR2032		Faint display, poor condition
Commodore	LC 925	2×AA
Commodore	?	9V
Commodore	899A	9V
Digi-Matic	DB-2	9V		Manual & case
Elektronika	MK-52			Not working
HP	10B	3×LR44
HP	10B	3×LR44
HP	10B II	2×CR2025
HP	17B II	3×LR44		Business
HP	32S II	3×LR44		Case
HP	48G+	3×AAA		Case
Lloyd's	ACCUMATIC 30	4×AA
Novus	Statistician 6030	9V
National Semiconductor	852	9V	1990
Realistic	Concertmate-200			(musical)
Scholastic	No name or model
Sharp	ELSI MATE EL-344A		1985
Sharp	EL-W535X (scientific)
Sharp	ELSI MATE EL-339	2×LR44
Sharp	EL-531X	LR44		Cover (scientific)
Sharp	EL-501XT	LR1130		Cover (scientific)
Sharp	ELSI MATE EL-8011	4×AA		Batteries don't work, wallwart
Sharp	EL-540D	CR2016, Solar
Sinclair	Sovereign	2×PX625A		Silver, case, manual, box (desk jewelry)
Swiss Micros	DM 16L	CR2032		Case (RPN, programmers)
TI	TI-83 Plus	4×AAA		(scientific programmable graphing)
TI	TI-36X SOLAR			(scientific)
TI	TI-30XIIS	CR2025		(scientific)
TI	TI-2550
Texas Instruments	TI-89 Titanium	4×AAA	2012
Toshiba	LC-848	2×LR54		Case (metric converter)
Tricom	Canadian Shoppers Calculator
Unitrex	mini 8	9V
Unitrex	802D	9V

Ambiguous Job References

Fri, 03 Nov 2023 11:39:41 +0000

Ambiguous references collected from various places.¹

Bad Influence

His contribution to the workplace is immediate and noticeable.
Her work ethic can influence the productivity of those around her.
She takes a lot of enjoyment out of her work.

Lazy

If you can get him to work for you, you will indeed be fortunate.
He has made immeasurable contributions to our firm.
In all the discussions she and I have had over the years, her salary never came up.
He works effortlessly.
To get the job done, we need ten employees like her.
You should seriously consider initiating an offer since she probably won’t apply herself.
When he worked for us, he never did anything halfway.
She could not care less about the number of hours she has to put in.

Annoying

I am pleased to say that this candidate is a former colleague of mine.
She is always trying.
His input was always critical.
She is one of the most discriminating people you’ll ever meet.
He was never away from the job too long.

Stupid

Attacking a difficult challenge, he doesn’t think twice.
We were forever asking her for new ideas.
There is nothing you can teach a man like this.
He is only 30, but he has the mental faculties of a man three times his age.
I would place her research on the cutting edge.
I would place this student in a class by himself.

Unmanageable

I have never seen a more diligent person on tasks that aren’t even required for the job.
I found myself frequently raving about her work.
He works without direction.

Creepy

He will take full advantage of his staff.

Incompetent

When he walks in every morning I know big things are about to happen.
Nobody would be better for the job than her.
The impact this employee had on our operations was astounding.
How did she manage those who worked for her? Quite fairly.
We were teetering on the threshold of bankruptcy last year, but her efforts pulled us through.
For the services he has rendered to our firm over the years, we find ourselves deeply indebted.
I recommend this candidate with no qualification whatsoever.

Generally Terrible

An employee like this is hard to find.
I cannot recommend this person too highly.
I simply can’t say enough good things about him.
He is a difficult man to replace.
I am sure that whatever task she undertakes — no matter how small — she will be fired with enthusiasm.
She is now ready to strike out in a career.
He is resigning a position that he has held with our firm for years. I truly wish there were more people like him.
You can’t offer this man too high a salary.
I would urge you to waste no time in making this candidate an offer of employment.

Footnote

Collected from: