Wednesday, May 6, 8:20 at night. Living room floor, laptop on the coffee table, hardware wallet warm in my palm with its tiny screen lit. A DeFi interface wanted a signature so my swap could go through, and my device answered with a warning I had tapped past maybe forty times. Blind signing. The screen could not read what it was approving, only I could, and tonight the little box held $8,900 in ETH and two tokens I had spent two years not losing.

Eight thousand nine hundred dollars. That number is a rebuilt transmission, or eleven months of my share of rent, or the entire reason my hands went cold at 8:21. The interface on my laptop looked ordinary, pastel buttons and confident fonts, the way an ATM looks ordinary right up til you notice a stranger's receipt still hanging out of the slot.

The device asked me to press both buttons to approve something it could not describe. Almost did. What stopped me was a detail I had skimmed twice: the request was not for an amount at all, it was for an allowance, and allowances have a way of never expiring. Ten minutes of hex reading stood between me and a click I would have spent months regretting, and it all began with four bytes I can now recognize forever.

the screen that said blind signing

Here is what the warning means, as far as I have pieced it together. A hardware wallet is a calculator that checks math, and when a transaction is a simple send, it can show you a to-address and an amount and ask nicely. Contract approvals are different animals. The payload is raw machine instruction, pages of it, and when the device cannot translate the pages it offers you the hexdump and a button that says approve anyway.

I had approved that button forty times. Forty. The wallet did not abruptly get dumber on attempt forty-one, which means my luck was simply scheduled to run out that week, on a Wednesday, in my socks, on my own floor.

$8,900 behind one blue button

The interface was a yield dashboard where I had parked 2,600 units of a mid-sized token, call it TKN, in a vault paying 7.1 percent. To move TKN anywhere, a contract needs your permission first, and that permission was the signature the device was chewing on. Standard stuff, mostly. Most approvals are written for a specific number, spend exactly 500 TKN and nothing more, and that is the version I assumed I was signing while the hex scrolled past like a receipt written in a language I never studied.

the four bytes that gave it away

Instead of pressing OK, I opened the companion app's raw-data view, copied the payload into a decoder I had installed months earlier for exactly this fear, and began reading. The function selector was 0x095ea7b3, which any approval decoder maps to the same two questions: who gets permission, and how much. The spender address matched the dashboard's contract. The amount did not match anything human.

It read 115792089237316195423570985008687907853269984665640564039457584007913129639935. That is the maximum value a 256-bit number can hold. Infinite, practically. The request was not asking to spend my 500 TKN, it was asking for a standing allowance over every TKN I owned or would ever hold, approximately $6,200 of it at that night's price, plus whatev sat adjacent in the same wallet. I checked the address twice. Then a third time.

ten minutes with a decoder and a kitchen chair

So I sat with it, hex line by hex line, for what my phone later told me was ten minutes and forty seconds. My wife asked if the shower was broken, cuz I had apparently been making one sound, a low hmm, for a quarter of an hour. Nothing on the screen changed the whole time. The dashboard waited with all the patience of a thing that has already won.

what the allowance would have meant

An unlimited allowance does not steal on day one. It sleeps. Any moment that dashboard's contract gets exploited, or its admin key walks out a door, or the site quietly changes hands, whoever holds the contract can pull the tokens it was granted, and my hardware wallet would never even light up, cuz no new signature is needed for a permission already given. The vault paying 7.1 percent would have been the cheapest thing I ever lost.

the reject button

I rejected the transaction at 8:41 PM. The dashboard sighed at me with a red banner, and I found the same vault position on a second interface that asks for exact-amount approvals, moved what I needed, and left the rest alone. Then I dug into the wallet's permission list, revoked two old unlimited approvals from 2024 I had altogether forgotten, both on tokens worth real money, and sat back down feeling like I had found a stranger's hand already inside my coat.

where the boring money sleeps

That scare rearranged my odds for good. The $8,900 stayed put, but the mental accounting moved: the crypto slice is the hobby now, capped at what I can watch burn without flinching. The actual future lives in a plain index fund at a hefty brokerage, plus an emergency fund parked in high-yield savings at 4.2 percent, where nothing needs a signature, an allowance, or faith in a stranger's smart contract. My father kept cash in a drawer his whole life and never lost a dollar to a decoder.

back on the floor, one last look

Later that night I picked the wallet up off the coffee table and looked at the same interface one more time. Same pastel buttons, same confident fonts, same request sitting there at 8:58 like it had all the patience in the world. The difference was me. Forty harmless approvals had made the button boring, and one honest hexdump made it dangerous again, which is exactly the right direction for fear to point.

The little screen is dark now, back in its drawer. It is not a talisman, it is a calculator that refuses to trust me on nights like May 6, and I have absorbed to say thanks out loud when it flashes that warning. Blind signing. Never on the first click again.