the provided text file shows really big numbers
- `lotta_numbers.txt`     ```    c: 34709089913401150635163820358938916881993556790698827096314474131695180194656373592831158701400832173951061153349955626770351918715134102729180082310540500929299260384727841272328651482716425284903562937949838801126975821205390573428889205747236795476232421245684253455346750459684786949905537837807616524618     p: 7049378199874518503065880299491083072359644394572493724131509322075604915964637314839516681795279921095822776593514545854149110798068329888153907702700969     q: 11332855855499101423426736341398808093169269495239972781080892932533129603046914334311158344125602053367004567763440106361963142912346338848213535638676857     e: 65537    ``` 
and if you haven't noticed the challenge name and description give off that this is a RSA algorithm challenge
- $p, q$  large prime numbers- $c$  is the ciphered message- $e$  is a part of the public key
now we can easily compute $n = p * q$ and we'll have the public key (e, n)
we can compute phi from $\phi(n) = (p-1) * (q-1)$
and lastly $d$ the modular inverse of $e$ from [`this calculator`](https://www.dcode.fr/modular-inverse)
the decrypted message can be acquired from the following formula:
$$m = c^d \enspace mod \enspace n$$
we have all the required parameters to crack the cipher so plug them into [`this calculator`](https://www.dcode.fr/rsa-cipher)
and u get the flag
![Screenshot](https://www.notion.so/Road-Safety-Association-de199ad00ba14c7ea1609a4b05e7c9d5#4b18cbf1c1f345e98c0f917912c31241)
### flag
`kqctf{y0uv3_6r4du473d_fr0m_r54_3l3m3n74ry_5ch00l_ac8770bdcebc}`