AlpacaHack Logo

Challenges

Sign InSign Up

Rows:

CHALLENGEAUTHORS

SOLVES

(CURRENT)

SOLVE RATE

(AT CONTEST TIME)

Welcome
Misc

admin

1407

solves

-

Daily AlpacaHack

1146

solves

-

Daily AlpacaHack

698

solves

-

AlpacaHack Round 2 (Web)

562

solves

Top 28%

= 84/300 users

Daily AlpacaHack

488

solves

-

Daily AlpacaHack

461

solves

-

Daily AlpacaHack

411

solves

-

echo
Pwn

AlpacaHack Round 1 (Pwn)

336

solves

Top 32%

= 56/174 users

Daily AlpacaHack

311

solves

-

Daily AlpacaHack

302

solves

-

Daily AlpacaHack

281

solves

-

Daily AlpacaHack

278

solves

-

Daily AlpacaHack

277

solves

-

Daily AlpacaHack

271

solves

-

Daily AlpacaHack

271

solves

-

Daily AlpacaHack

268

solves

-

🐈
Web

Daily AlpacaHack

266

solves

-

AlpacaHack Round 7 (Web)

265

solves

Top 15%

= 71/458 users

Encoding Basics
Misc
Crypto

Daily AlpacaHack

261

solves

-

qrime
Crypto

AlpacaHack Round 3 (Crypto)

245

solves

Top 38%

= 91/239 users

Rows:

a fact of CTF

Daily AlpacaHack
698 solves
Crypto

Author:

The very first challenge ever completed for AlpacaHack was never released because we adjusted the difficulty for the first Crypto round. (Organizers' note)

Beginner Hint
  • This challenge is in the Crypto (Cryptography) category.
  • AlpacaHack currently features four main categories: Crypto, Pwn, Rev, and Web; everything else goes into Misc.
  • Start by downloading the attached a-fact-of-CTF.tar.gz and extracting it.
  • In chall.py, the environment variable FLAG is read. This is the flag.
  • The flag is then transformed using prime numbers.
  • The output of chall.py is output.txt.
  • The goal is to recover the flag from the value in output.txt.
a-fact-of-CTF.tar.gz
descriptionsolveswriteups