The Seed Phrase Swap-Out

Tucker Carlson recently got detained at Ben Gurion airport in Israel. My mind raced ahead when I heard this. I thought: “I bet they take his phone and put spyware on it.” Even though it seems that Carlson’s drama was overhyped, I don’t think my imagination was straying down fanciful alleys. Imagine yourself taken aside at customs. “Give me your PIN; I need to check your phone.” “Okay,” you’ll say. At this point, you’ll be glad you stelled¹ some kind of app-hider; so your Phoenix Wallet looks like Ludo King.

That's not enough.

Let’s give the wankers in uniform the runaround.

Analog is best

This post is for the travellers, and especially for the long-term travellers or emigrants.

While travelling, crypto is easiest. You should keep a few hundred dollars worth on a smartphone, and keep your serious coin on paper. I mean, write down your seed phrase. Hide it on your person. You don’t need to hide it especially well. In fact, it might be fun for some official to get his or her hands on it. Doesn’t that mean ‘game over’ for your crypto savings? No. On the contrary, it means ‘game on’.

Seed Phrases overview

Before I lay out the game we can play with these petty functionaries, let’s go over seed phrases quickly, as you might be a bit murky on them, and they need to be understood. A seed phrase looks something like this:

A seed phrase works like a password, but it’s more. It’s actually a lexical representation of your master private key.² Imagine that your access code to your storage unit is 132 digits long. (You have the tapes from Zorro Ranch). Chances are, you’ll screw up one of those digits. But, if you split that long number up into segments, and map each segment to a word, it’s much easier to deal with. It will work so long as there is a shared ‘code-book’ of sorts, so that everyone knows that 856 maps to ‘civil’, and so forth.

Crucially, the words need to stay in order. They’re segments of a number— one can’t change the order of digits in a number. 12,345,675 is not the same as 12,345,765.

The Seed Phrase Swap-Out

Let's work with this seed phrase:

1. Memorize seed words 1 and 2, and erase them.

“Bye-bye words 1 and 2.” You memorized them first, of course.

2. Choose a special but quite private date.

You need a personally meaningful date. Not your birthday or wedding anniversary. That’s too blatant. I suggest the birthdate of your favorite pop star. We need the year. Let’s say your favorite pop star is Cyndi Lauper. We will use Cyndi Lauper as the example.

1. Find out Cyndi Lauper’s birthdate, 22nd of June, 1953.
2. Use the year, formatted as ‘—yy’ = 53.
3. Split the year part into two digits: 5, 3.
4. Treat a zero as 10.
5. Treat double-zero, 00, as a 10 and 11.
6. Memorize the seed words in those positions, e.g. 5, 3, and erase them.

The good thing about the pop star’s birthdate is that you can look it up easily if you forget it.

3. Replace the erased words from your special date with legitimate subsitutes.

1. For bitcoin, look up the legitimate set of words, for example here. Other cryptocurrencies might use the same list, i.e. BIP-39. Otherwise, find your cryptocurrency’s list.
2. Choose any two words.
3. Put them in place at positions 5 and 3, where you just erased.

4. The end result.

We are left with a piece of paper looking like this:

Make a copy, and keep it hidden at home, just in case your original gets confiscated.⁴

I’m sure you are aware of the importance of hiding seed phrases. The thing is: The two missing words (at 1 & 2) put your crypto tantalizingly close, it would seem. There aren’t too many combinations to go through; at least, not for a computer. Two missing numbers give about 4.2 million combinations. Most of the words will fail in milliseconds. That is because the twelfth word holds a checksum. On the other hand, one can only know whether it has really worked or not by checking the blockchain, and this takes some time. It’s probably fair to say that two missing numbers will need a couple of hours to crack.

It doesn’t really matter. However long, it’s a waste of time.

The scene at the airport, 2029AD…

“Step aside please.”

“Great,” you mutter sarcastically. You’re tired. You’re only 30 minutes from seeing your cat again after two weeks. Oh yeah, kids too.

Unfortunately, your name in your passport has triggered some A.I. bullshit program that the airports are using now.

In a big room, with a dozen desks and a dozen others suffering your fate, a fat, fake-smiley woman has done everything but ask for a strip-search, and that’s almost certainly on the cards.

“May we look in your shoes?”

Can’t really say “no.”

You see the glint in her eye as she finds a piece of paper with your seed phrase on it. She turns away from you. Her body shields her action. You can guess. She is taking a photo of it.

“You’ll need to wait while we check something.”

You try not to smile as you sit there. You know that she has instant-messaged your seed phrase to the boffins, and you can picture the scene:

Two middle-aged nerds with their flies only done up 75% hunch over a computer.

“The dipshit must have written down a wrong word.”
“Nah. I reckon the Electrum server is down.”
“It’s not.”
“Let’s run the program overnight.”

Why your crypto is safe

The problem is that any of the words could be wrong. Since the wrong word needs to be taken out at the right place at the same time as another wrong word at the right place, the calculations will crank on for months. That gives you enough time to transfer your funds to a new address.

Swapping-out words of a seed phrase on paper are old tricks. My original take on it, is that I make the first two seed words blank, as bait. If you just swap-out words, they’ll realize they have been duped in a few minutes. I actually want the bastards to get all keen and haughty.

Il faut agacer les fonctionnaires.⁵