JordiGH @JordiGH@mathstodon.xyz

Time for new #introductions!

I'm Jordi, a newly-minted #Canadian from Mexico, living in #Montreal. I've had a super-sheltered and comfortable life. Nothing dreadful has ever happened to me.

I like #mathematics, #knitting, #skating, #swimming, and old #gameing because I'm old (not that old).

I also do software stuff because of course.

Day job is work on #GreenhouseGas assessments and #environmental #mapping, but my nocturnal alter-ego is writing a book in 2021, streaming on Twitch!

I'm kind of grateful that another smart cow (re: https://en.wikipedia.org/wiki/Smart_cow_problem ) figured out most of how Crypto-JS works so that I could decrypt my own savegame. But why do this to begin with, gamedevs? This is silly.

In the end it was something like this, where bytes_to_key is that function from the Stack Overflow link above. The decryption password is ":_.NaN0", so very javascripty.

encrypted = base64.b64decode(sav['slots'][0][9:])

salt = encrypted[8:16]
key_iv = bytes_to_key(b':_.NaN0', salt)

key=key_iv[:32]
iv=key_iv[32:]

aes = AES.new(key, IV=iv, mode=AES.MODE_CBC)
aes.decrypt(encrypted)

Huh, interesting, so I think I managed to decrypt it, but there seems to be some non-JSON junk on either side of my savegame. I can now read most of it, though.

Gah, it gets complicated. Apparently to decrypt, you have to undo whatever the hell Crypto-JS decided to do:

https://stackoverflow.com/questions/27220297/what-are-the-aes-parameters-used-and-steps-performed-internally-by-crypto-js-whi

So I'm trying to figure out the right parameters to decrypt #CrossCode's save games and in the process I'm accidentally learning more details about how #AES works.

Currently trying to figure out how we go from a passphrase to a 32-bit encryption/decryption key. Looks like it should be hashed, but I think they're using a particular library implementation that picks a hash for you. So, now I'm reading CryptoJs's source so I can figure out how they hash the passphrase.

Okay, how did we end up naming anything after Cholesky anyway?

Now I want to look this up.

Oh, cool, apparently a rare meaning of "dragon" in #Unix is a daemon that is always sleeping, in the background, waiting to act, and wasn't explicitly summoned.

So here's why I was thinking of Cholesky.

Consider the \(n \times n\) matrix \((a_{ij})\) full of Pascal's triangle along the antidiagonals:

\[a_{ij} := {{i+j+2} \choose {j-1}}\]

For example, for \(n = 4\) the matrix is
\[\begin{pmatrix} 1 & 1 & 1 & 1 \\
1 & 2 & 3 & 4\\
1 & 3 & 6 & 10 \\
1 & 4 & 10 & 20
\end{pmatrix}.\]

What is \(\det (a_{ij})\) ?

Oh boy, I've been mispronouncing "Cholesky" all of my adult life. 😳

I took a screenshot of a virtual desktop then viewed that screenshot in full screen mode. Switched to a different virtual desktop and forgot about it. Switched back to the first virtual desktop and it took me a few seconds to understand why my screen was frozen.

The Titanic was carrying the first shipment of Mayonnaise to the United States. It sunk, and that is what we celebrate today.

Having a role-playing-game-induced debate on whether wooden daggers can also kill vampires or if they have to be specifically stake-shaped. Do vampire hearts detect the specific shape of the wood?

Okay, so I got Lea's hair and the horns... on top of the horns.

Not sure if that's enough or if I should also try to get the rest of her outfit on.

#CrossCode

And because they're all the same, their individual cultures don't matter! They're just a bland, pasty white, insipid mixture, without any distinguishing features other than being white.

So, yeah, if you've been told that you have no culture because you're white, that's a lie. It's a white supremacy lie designed to make you band with people who are or were otherwise quite culturally different from you.

The whole white-has-no-culture thing is kind of a white supremacy thing to begin with. Everyone in the US from many different backgrounds had to band together under one banner. How do you get people with Irish, German, English, Scottish, and Italian backgrounds to all get together and unite against black people in order to justify slavery? You tell them they're all white!

Of course the US has a culture and of course white peoples have cultures. Different parts of the US and Europe have very varied cultures.