The Nineteenth Byte

4:53 PM

@user202729 True

flawr

6:18 PM

@Riker /r/BrandNewSentence/

Anush

7:28 PM

hi all

If I give you a number, say x= 2^5^3^4^2 , is it hard to list all the other numbers that are towers of 5 integers that are exactly equal to it?

restricting all the integers to 1 to 10

7:40 PM

@MilkyWay90 is this for saved games? seems fine to me, why should that be super encrypted

@Anush 'tower'? do you mean power tower?

8:07 PM

@Riker I meant it arbitrarily mashes different encryption methods. This is for the save data of your account, yes

Anonymous

8:24 PM

@MilkyWay90 Only one of those is an encryption method

dzaima

@Mego which of those is an encryption method? xor would be the closest but it more feels as someone having nothing to do on a job and randomly adding it in because why not

it probably does its job of getting 99% of people to stop trying to decode it, which is probably the most you can realistically do without making extremely obfuscated hand-crafted undebuggable assembly

@dzaima xor is definitely an encryption method, zlib is a compression algorithm so of course they'd use it, b64 is likely used to make it easily compressible from bytes -> text -> compression (zlib) text

I haven't read through the file milky posted though, this is just a guess

dzaima

@Riker it's xor with a single constant byte key for every character though

Anonymous

@dzaima A bad encryption method is still an encryption method

so it's badly done encryption? I'm not sure there's anything to secure there lol

yea what @Mego said

Anonymous

8:38 PM

XOR encryption with a block size of 1 byte is not very strong, but it's good enough for the purposes of save game data

"oh no, my enemies are going to find out I haven't beat this level, oh no"

Anonymous

In the next game I make, savefiles will be encrypted with 2048-bit AES

Anonymous

No kill like overkill

8:57 PM

I see

@Mego @dzaima @Riker github.com/MilkyWay90/MilkyWay90.github.io/blob/master/…

Is one of the files

The rest are:

github.com/MilkyWay90/MilkyWay90.github.io/blob/master/…

@Riker You would have to zlib.decompress(base64.b64decode(data.replace('-','+').replace('_','/').encode())[10:],-zlib.MAX_WBITS) the levels to get an ASCII-only version of the levels and even that is hard to understand

But Absolute Gamer/Italian Apk Downloads have figured it out

But they compiled the Python program they used to convert an image to a Geometry Dash level, so I will never know the secrets to the level format

hence why I asked chat.stackexchange.com/transcript/message/50073403#50073403

@MilkyWay90 that line was sarcasm just fyi

If anyone could help me figure it out, that would be helpful

@Riker I see

9:34 PM

@Anush I've thought a bit about that recently. Two towers cannot be equal unless their base numbers are powers of a common one. For that particular example that implies that the 2^5^ part is fixed, and that 2^5^3^2^4, 2^5^9^2^3 and 2^5^9^8^1 are the possible options.

Something like 3^2^c^d^e might be harder to handle, though, since you end up having to check if c^d^e-1 is a power, and it might be large. (In which case it fits with 9^2^.)

Anush

@Riker yes

I think it's likely that subtracting 1 or 2 from a large power never gives a power, though.

Oh, 1 is a theorem now...

Catalan's conjecture

9:55 PM

You also have to check if (c^d^e-1)/2 and (c^d^e-1)/3 are powers, for 9^4^ and 9^8^.

There are few enough candidates that you can use the logarithm method from the earlier challenge to estimate which ones might fit, though.

And I suspect there won't be any large ones which do.

10:15 PM

@ØrjanJohansen is th 2^5 fixed or the 2 on the bottom?

Both. The 2 cannot be changed to 4 or 8, because 5 isn't divisible by 2 or 3. The 5 cannot be changed because 25 > 10.

Οurous

10:38 PM

TIL by experience: building clang from source can be a good whole-system benchmark.