# Key generator
>Reversing
>Points - 300
>This is our official key generator that we use to derive keys from machine numbers. Our developer put a secret in its code. Can you find it?
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Reversing the given binary you'll discover a couple of things:
1. It checks, whether or not the entered string has a length of `7` and stops/continues execution accordingly.
![strlen](./strlen.png)
2. It compares the input string to the static string `laska!!`.
![strrev](./strrev.png)
This is were it gets interesting:
* if the strings don't match, it'll just generate some random serial number according to this pattern:
```inp[6]-6 + inp[5]-5 + inp[4]-4 + ... + inp[0]-0```
* if the string do match, however, it calls the function `octal()` which prints the following:
```1639171916391539162915791569103912491069173967911091119123955915191639156967955916396391439125916296395591439609104911191169719175
You are not done yet!```
actually, the last step isn't too difficult anymore . The kind message tells us that we're not done yet and the name of the function that prints this gives us a good hint at what could possibly still be missing: `octal()`.
Simply split the weird long string at every `9` (since this obviously doesn't exist in octal) and decode the resulting string using the octal character codes:
```163 171 163 153 162 157 156 103 124 106 173 67 110 111 123 55 151 163 156 67 55 163 63 143 125 162 63 55 143 60 104 111 116 71 175```
this gives us the flag: `syskronCTF{7HIS-isn7-s3cUr3-c0DIN9}`