$ ctf42

Crypto CTF challenges

4,483 Crypto CTF challenges from 404 CTFs (2011–2026), 708 with writeups.

Top crypto techniques

#rsa 106 #xor 16 #lattice 16 #known-plaintext 12 #substitution-cipher 12 #lll 11 #crt 10 #diffie-hellman 9 #ecdsa 9 #discrete-log 9 #meet-in-the-middle 8 #caesar-cipher 8 #lfsr 8 #padding-oracle 8 #hastad-broadcast 7

Challenges

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Challenge CTF Weight Has
What_the_Flip
#aes-cbc#bit-flipping-attack
 DawgCTF 2021 23.29 files wu 2
TagSeries2 WolvCTF 2024 35.25 files wu 2
Delta_Force TSG 2023 – files wu 2
ProvablySecure DiceCTF 2023 36.70 files wu 2
ProvablySecure2 DiceCTF 2023 36.70 files wu 2
baby-rsa TJCTF 2023 – files wu 2
WarmupEncoder 1337UP 2022 22.49 files wu 2
ABitWeird UTCTF 2021 – files wu 2
Draupnir Balsn 2021 37.00 files wu 2
Encoding TAMUctf 2021 – files wu 2
Enkripter MetaRed 2021 – files wu 2
Ransomware_Patch MetaCTF 2021 – files wu 2
ReallynotSecureAlgorithm PBjar 2021 23.18 files wu 2
Sleeves UTCTF 2021 – files wu 2
Stars_and_Shapes DeconstruCT.F 2021 19.69 files wu 2
WeirdMessage VishwaCTF 2021 – files wu 2
chaos Zh3r0 2021 – files wu 2
madras ASIS 2021 Quals 89.22 files wu 2
Cat-0-Graphy
#zip-cracking
 eHaCON 2021 – files wu 1
the-other-css
#z3#lfsr#css-cipher
 PlaidCTF 2023 100.00 files wu 1
Cozzmic_Dizzcovery
#xor-state-recovery
 K3RN3LCTF 2021 24.37 files wu 1
one_time_beach
#xor-known-plaintext
 ISITDTU 2021 Quals 23.08 files wu 1
dhash
#xor-cancellation
 IrisCTF 2024 24.59 files wu 1
Baby-Xor
#xor#self-shifted-xor
 S4CTF 2021 24.52 files wu 1
Either_or_Neither_nor
#xor#repeating-key#bruteforce
 RITSEC 2023 – files wu 1
XOR_101
#xor#repeating-key
 squ1rrel 2025 24.25 files wu 1
OTP2
#xor#known-plaintext
 BlueHens 2021 22.62 files wu 1
Exclusive
#xor#brute-force
 WORMCON 2021 – files wu 1
To_Be_Xor_Not_To_Be
#xor
 UMDCTF 2021 – files wu 1
Letter_Soup
#word-search#rot13
 DEADFACE 2023 – files wu 1
nitwit
#winternitz-ots-forgery
 BuckeyeCTF 2025 – files wu 1
RSA_Bummer
#wilsons-theorem#rabin-cryptosystem
 BITSCTF 2025 – files wu 1
hot_diggity_dog
#wiener-attack
 BlueHens 2021 22.62 files wu 1
Where_Snakes_Die
#whitespace-steganography#morse-code
 BxMCTF 2023 – files wu 1
Eggs_Over_Easy
#whitespace-steganography
 BlueHens 2026 44.77 files wu 1
Baby_RSA
#whitebox-rsa#key-extraction
 CCCamp 2023 25.00 files wu 1
hyperhyper
#weil-pairing
 hxp 2020 94.00 files wu 1
TheSecretImage
#visual-cryptography#image-subtraction
 VishwaCTF 2023 22.69 files wu 1
Vinegar_Times_3
#vigenere-cipher
 BCACTF 2024 – files wu 1
Ep3.9
#vigenere-cipher
 Jade 2022 23.95 files wu 1