In their defense, they were probably targeting the Mersenne prime 2^2 - 1 and just made a typo.

> In their defense, they were probably targeting the Mersenne prime 2^2 - 1 and just made a typo.

There are two hard problems in computer science: naming things, cache invalidation, and off-by-one errors.

Two, and only two?

You have almost understood the joke.

two is off-by-one from three btw

But the cache invalidation failed

Well:

    There are actually only two hard problems in computer science:
        0) Cache invalidation
        1) Naming things
        4) Asynchronous callbacks
        2) Off-by-one errors
        3) Scope creep
        6) Bounds checking

* https://news.ycombinator.com/item?id=38806257

Also: https://martinfowler.com/bliki/TwoHardThings.html

ok, it's joke. but for those who don't get it: elliptic curves don't need primes

It’s really impressive no one caught their three previous private key values

I suspect they did but it wasn't publicised.

They should have gone with 57. Everyone knows it's prime.

Alex? You're alive after all?

I wonder if anyone wants to over-analyze this joke to come up with the best candidates for the number? 57 falls too easily to the quick divisibility by 3 trick, IMO. (I realize over-analyzing jokes always makes them unfunny but we can pick the best number here and nobody has to know).

Me! I'm in!

Most-nearly-prime number under 100 is.... 91.

13 x 7. You've either memorized that or you're going to have fun deciding it's not prime. And if you did times tables up to 13, congratulations, you're special.

7 is an easy check, not because i did them up to 13.

because 10x7 = 70, i'm left with 21. everyone knows 21 is divisible by 7.

I think 91 is a strong contender. Sejje has a way of working it out, but of course any small non-prime will have some trick to it.

It's been a while since this one popped up. It's surprising how many of those doodles are surviving the test if times, in the midst unexpected ways

Hey, that's the same combination I have on my luggage!

Good job the Earth doesn't have an air shield protected by this byte or we'd be Skroob'd.

The number 4 is very famous.

https://xkcd.com/221/

it doesn't have to be and it actually never is: this isn't RSA, it's an elliptic curve algorithm. if you'd have read the article, you'd have understood this