Jump to content
View in the app

A better way to browse. Learn more.

Tuts 4 You

A full-screen app on your home screen with push notifications, badges and more.

To install this app on iOS and iPadOS
  1. Tap the Share icon in Safari
  2. Scroll the menu and tap Add to Home Screen.
  3. Tap Add in the top-right corner.
To install this app on Android
  1. Tap the 3-dot menu (⋮) in the top-right corner of the browser.
  2. Tap Add to Home screen or Install app.
  3. Confirm by tapping Install.

Featured Replies

Posted

Blackett

The real goal is to make a keygen capable of generating infinite valid combinations of name and keys. 

Btw, also a valid serial is appreciated :)

The only protection used is renaming.

Good luck!

@kao Long time no see 🧐

File Information

Submitter LoLLo90

Submitted 09/13/2020

Category KeygenMe

View File

Blackett

Solved by 0xret2win

Go to solution
  • Author

Btw, here is a little hint:

 

hint.png

  • Author

No one willing to try this challenge?

Another hint: 

"Erjey" is the equality relation..

"Tuts4you" is the greater than or equal relation..

  • 2 weeks later...
  • Author

One valid combination:

Immagine.png.a2c06a962bb5fa866bd1cce501063e11.png

  • 4 years later...
  • Solution

Hi! I took a look at it and shame that no one tried to solve it,here is my approach.

Basic things i pulled:

All four keys must differ.

If any two keys are the same string, it shows “All keys must be different.”

No key can contain "0@0".
If you type a key like "0@0@something", it rejects it.

“Erjey” can be used at most once, and if it appears, the fourth chunk of that key must be less than 6.
That is, if a key has the substring "erjey", its format is X@Y@erjey@W, and W<6W < 6W<6.

The third chunk in each key can be one of three strings:

  • erjey
  • kao
  • tuts4you

If you use something else, you get badboy error message.

2.2. Internally, a Linear Solver

Digging deeper, i discovered a set of classes (d, e, j, etc.) that build a system of linear equations or inequalities. Each key of the form 

X@Y@{erjey|kao|tuts4you}@W

is taken to mean X⋅x+Y⋅yRELWX , where the “relation” REL depends on the keyword:

  • erjey → equality (=).
  • kao → some inequality (≥ or ≤) depending on puzzle logic.
  • tuts4you → the other inequality.

From hints in the code and trial tests, we saw that:

erjey is effectively “=”.

For this puzzle’s code, kao ended up being “≥” and tuts4you was “≤” (the code flips them).

Finally, after the solver ensures a feasible solution for (x, y), it calculates an “objective value” from the Name field, which must also be in the format A@B (two doubles). The code uses: objective=A×x+B×y

 

If that objective is exactly 44 000, it shows:

MessageBox.Show("Valid combination!");

That is the central condition:

Ax+By=44000.

3. Constructing a Solution

To guarantee the solver yields 44,000, we needed to pick (x, y) and (A,B) so that:

A×x+B×y=44000.

Additionally, we had exactly four constraints (the “Keys”) to pin down x and y.

3.1. The Simplest Trick: Set x=y

One common approach: force x=y=c for some integer c < 6 (because the puzzle disallows “erjey@W” if W >= 6). Then we just need:

(A+B)×c=44000 then this becomes A+B = 44000 / c

Hence, pick any c in [1..5], and pick A + B = 44000 / c.

3.3. Example Name

Then to satisfy (A+B) c=44000, choose a Name that splits as A@B with A+B=44000/c. For instance:

Let c = 4. Then A+B must be 11000.

We pick A = 5500 and B = 5500.

So Name = "5500@5500".

3.4. Putting It All Together

Spoiler

Name: 5500@5500

Key1: 1@0@erjey@4

Key2: 0@1@kao@4

Key3: 0@1@tuts4you@4

Key4: 1@-1@tuts4you@0

And if im right and if this is the keygen you have asked for :

keygen.py

Edited by 14yoKID

Create an account or sign in to comment

Configure browser push notifications

Chrome (Android)
  1. Tap the lock icon next to the address bar.
  2. Tap Permissions → Notifications.
  3. Adjust your preference.
Chrome (Desktop)
  1. Click the padlock icon in the address bar.
  2. Select Site settings.
  3. Find Notifications and adjust your preference.