n00bzCTF
🩸rsa [100 pts]
Writeup author: lolmenow
Provided files: encryption.txt
Description:
The cryptography category is incomplete without RSA. So here is a simple RSA challenge. Have fun! Author: noob_abhinav
Looking at encryption.txt, we see the public exponent being 3. I instantly thought cube root RSA exploit, and used rsacracker on the values, which decrypted it instantly.
$ rsacracker -n 135112325288715136727832177735512070625083219670480717841817583343851445454356579794543601926517886432778754079508684454122465776544049537510760149616899986522216930847357907483054348419798542025184280105958211364798924985051999921354369017984140216806642244876998054533895072842602131552047667500910960834243 -e 3 -c 13037717184940851534440408074902031173938827302834506159512256813794613267487160058287930781080450199371859916605839773796744179698270340378901298046506802163106509143441799583051647999737073025726173300915916758770511497524353491642840238968166849681827669150543335788616727518429916536945395813
Running [00:00:00] [====================> ] 9/40 Elapsed time: 50.898601ms
Succeeded with attack: cube_root
Unciphered data:
Int = 235360648501923597413504426673122110620436456645077837051697081536135487875222175025616363200782717
Hex = 0x6e3030627a7b6372797074305f31735f316e63306d706c3374335f773174683075745f72733421217d
String = "n00bz{crypt0_1s_1nc0mpl3t3_w1th0ut_rs4!!}"
There is our flag!
Final flag: n00bz{crypt0_1s_1nc0mpl3t3_w1th0ut_rs4!!}