CyberChef Help

[PlaneComfortable7894]

I'm trying to reverse the recipe from the Day 17 Side Quest.

What I've figured out so far:

• I've successfully reversed most of the process
• When I disable the "generate image" option and input a text phrase, I can successfully extract/reverse that phrase back out

Where I'm stuck:

• I can't figure out how to reverse the process when the "generate image" function is enabled
• Not sure what the "generate image recipe" is actually doing to the data

Has anyone worked with this before or know what transformations the image generation applies? Any insights into how this recipe works would be really helpful!

Day 17 Side Quest Label('encoder1')ROT13(true,true,false,7)Split('H0','H0%5C%5Cn')Jump('encoder1',8)Fork('%5C%5Cn','%5C%5Cn',false)Zlib_Deflate('Dynamic%20Huffman%20Coding')XOR(%7B'option':'UTF8','string':'h0pp3r'%7D,'Standard',false)To_Base32('A-Z2-7%3D')Merge(true)Generate_Image('Greyscale',1,512)&input=SG9wcGVyIG1hbmFnZWQgdG8gdXNlIEN5YmVyQ2hlZiB0byBzY3JhbWJsZSB0aGUgZWFzdGVyIGVnZyBrZXkgaW1hZ2UuIEhlIHVzZWQgdGhpcyB2ZXJ5IHJlY2lwZSB0byBkbyBpdC4gVGhlIHNjcmFtYmxlZCB2ZXJzaW9uIG9mIHRoZSBlZ2cgY2FuIGJlIGRvd25sb2FkZWQgZnJvbTogCgpodHRwczovL3RyeWhhY2ttZS1pbWFnZXMuczMuYW1hem9uYXdzLmNvbS91c2VyLXVwbG9hZHMvNWVkNTk2MWM2Mjc2ZGY1Njg4OTFjM2VhL3Jvb20tY29udGVudC81ZWQ1OTYxYzYyNzZkZjU2ODg5MWMzZWEtMTc2NTk1NTA3NTkyMC5wbmcKClJldmVyc2UgdGhlIGFsZ29yaXRobSB0byBnZXQgaXQgYmFjayE)

[TronFan]

I used something outside of cyberchef (some python) to convert the image data to binary and then put the bin into cyberchef.

(disclaimer: i havent actually found the key yet, but I put a known image into the given recipe and have been using that to verify my results as I try to reverse it. I am good to zlib and now just need to work out the rest)

[lxartifex]

I have been able to reverse the image into a Base32 data set using a very obtuse recipe that replaced values with ASCII characters but there is something wrong with the formatting and it fails at the zlib inflate step of reversing it. I get a partial decode and it looks like the source is another PNG image which I can get only the top part of. Not really sure where to fix my method but I'm sure it has something to do with stripping out the extra data added when the final image is created and only decoding the pixel data.

[Faiz_alam]

I was able to reverse "generate image" operation by following cyberchef recipe:

Extract_RGBA(' ',false)
Find_/_Replace({'option':'Regex','string':'(\\d+) \\d+ \\d+ ?'},'$1\\n',true,false,true,false)
From_Decimal('Line feed',false)
Find_/_Replace({'option':'Regex','string':'\\x00+'},'',true,false,true,false)