Reverse engineering visual novels: tackling the script

[mnakamura]

Hi, fellow VN hackers,

Some of you might remember that I wrote the first part of visual novel reverse engineering guide a while ago.

And now, lo and behold, today's the day that I've published the second part of reverse engineering tutorial - this time, I'm discussing the approaches to reverse engineer the script, find out what are the part it consists of, and extracting the Japanese text (to pass it to the translators, if you run a VN translation project).

Feel free to ask any questions. Cheers

[Infernoplex]

I have never seen you or your previous guide but I can safely say that this is probably the most interesting thread that I have stumbled upon on Fuwanovel and right now I am reading both your new guide and the previous one!

Thank you very much for your effort on trying to explain the process, I am actually very interested in the problem of VN hacking

Edit: I have just finished reading both tutorials ... I need to be honest with you, this kind of stuff requires some basic background knowledge on the matter for the learner, l think I am not able to reproduce what you have done (I didn't try it for myself but will probably when I get the time) ... What I find hard in your tutorial is that it actually requires a lot of background knowledge on the matter, for example, you already know some specifics about data types and what means what and that's why you can easily deduce some things ... I for example don't have that kind of knowledge and would have never been able to deduce some of the things you mentioned because I lack knowledge in that field and was never studying reverse engineering xD ... For extraction purposes I always use tools provided by others and that's all I am able to do now because this type of thing you are able to pull out is several light years far away from me Though I do find these type of things interesting, I would definitively need more knowledge on the matter, this stuff is not for beginners! XD

Edit2: Hypothetically asking but ... do you have an idea how would you, for example, put the scripts or images back in the ".ykc" container?

Edit3: Okay, this will be the last edit, you got me interested on the matter and so I decided to learn more and I stumbled upon this which kind of reminded me of your guide and right now I am looking for all kinds of study material on the matter ... I found some "Reverse Engineering" books but I think they are specifically written for malware analysis like this book for example and I am trying to find something with more practical approach on the matter of unknown file extraction and reading aswell as putting it all back together (yeah, I am interested mostly in VN hacking xD)

Edited October 4, 2016 by Infernoplex

[mnakamura]

11 hours ago, Infernoplex said:

I have never seen you or your previous guide but I can safely say that this is probably the most interesting thread that I have stumbled upon on Fuwanovel and right now I am reading both your new guide and the previous one!

Thank you very much for your effort on trying to explain the process, I am actually very interested in the problem of VN hacking

Thanks for your appreciation It's really very heart-warming to know that someone (besides me) finds that stuff interesting

11 hours ago, Infernoplex said:

Edit: I have just finished reading both tutorials ... I need to be honest with you, this kind of stuff requires some basic background knowledge on the matter for the learner, l think I am not able to reproduce what you have done (I didn't try it for myself but will probably when I get the time) ... What I find hard in your tutorial is that it actually requires a lot of background knowledge on the matter, for example, you already know some specifics about data types and what means what and that's why you can easily deduce some things ... I for example don't have that kind of knowledge and would have never been able to deduce some of the things you mentioned because I lack knowledge in that field and was never studying reverse engineering xD ... For extraction purposes I always use tools provided by others and that's all I am able to do now because this type of thing you are able to pull out is several light years far away from me Though I do find these type of things interesting, I would definitively need more knowledge on the matter, this stuff is not for beginners! XD

Hmm, and I thought that I'm referring only to the most basic stuff in these articles. What do you need to know to understand them?

• very basic stuff about how computers work - i.e. files, hex numbers, bits-bytes, integers, characters - I guess most of the people nowadays learn that in mid school / high school
• the rough idea of string encoding - i.e. that "string" is a sequence of characters, and you need know somehow where the string ends - for that you either store a string's length somewhere, or declare that a string needs some "terminator" character
• basic knowledge of any modern object-oriented programming language (from those supported by Kaitai Struct)

I supposed that basically anyone who spent like a weekend trying to pick up any progamming language (i.e. Ruby, Python, JavaScript, etc) would be ok with reading my tutorials.

Can you elaborate more on what exactly is missing and what's hard to read/understand? Even if it's that "basic" stuff I've mentioned above - maybe it would be a good idea to write some quickie explaining it all in one place?

11 hours ago, Infernoplex said:

Edit2: Hypothetically asking but ... do you have an idea how would you, for example, put the scripts or images back in the ".ykc" container?

Well, of course I do, but as you might have noticed, I'm kind of really opposing the idea.

11 hours ago, Infernoplex said:

Edit3: Okay, this will be the last edit, you got me interested on the matter and so I decided to learn more and I stumbled upon this which kind of reminded me of your guide and right now I am looking for all kinds of study material on the matter ... I found some "Reverse Engineering" books but I think they are specifically written for malware analysis like this book for example and I am trying to find something with more practical approach on the matter of unknown file extraction and reading aswell as putting it all back together (yeah, I am interested mostly in VN hacking xD)

There's a whole world of reverse engineering that one can learn and hone their skills for the whole life There are several pretty distinct branches: analysis of execution (that usually

As for books, I could really recommend https://beginners.re/ - it's a little slow-paced at some topics, but good nevertheless.

[Infernoplex]

... Me - sad ... Sorry, I made a long post and totally forgot to copy it before clicking "Submit Reply" ... I forgot that for some reason Fuwa always requires you to kind of login again after an hour of your online activity has passed (not really login, you just go through standard Cloudflare redirect) ... So, yeah, all is lost I hate this, this is the second time it happened to me on Fuwanovel but oh my, I guess now I will learn that I should always copy it before clicking "Submit" ...

Anyway, I thank you for your recommendation on the book by Yurichev, I have downloaded it and will definitively check it out.

As for your tutorial, I think I will try to elaborate on it some other time, I don't have energy to type it all again

[mnakamura]

10 hours ago, Infernoplex said:

... Me - sad ... Sorry, I made a long post and totally forgot to copy it before clicking "Submit Reply" ... I forgot that for some reason Fuwa always requires you to kind of login again after an hour of your online activity has passed (not really login, you just go through standard Cloudflare redirect) ... So, yeah, all is lost I hate this, this is the second time it happened to me on Fuwanovel but oh my, I guess now I will learn that I should always copy it before clicking "Submit" ...

I totally feel you, pal, happened to me 2 or 3 times already. Damned Cloudflare

Best luck with your reversing efforts anyway. Please share your progress with us — that's always very cool to see