$ 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
RobustCBC
#cbc-mac#mac-forgery#truncation-collision
 SekaiCTF 2022 24.86 files wu 1
Flip_Me_Over
#cbc-bit-flipping
 niteCTF 2021 – files wu 1
1n_jection
#cantor-pairing#recursive#inverse-pairing
 Zh3r0 2021 – files src wu 1
Attn_Agents
#caesar-cipher
 JerseyCTF 2024 21.26 files wu 1
Coin_Code
#caesar-cipher
 DEADFACE 2023 – files wu 1
spin
#caesar-cipher
 WRECKCTF 2022 – files wu 1
DealBreaking
#caesar-cipher
 TrollCAT 2021 21.87 files wu 1
casino
#business-logic-flaw#negative-value
 TetCTF 2023 53.89 files wu 1
Trouble_With_Pairs
#bls-signature
 InCTF 2021 70.41 files wu 1
quantum_cipher
#block-cipher-cryptanalysis
 TRX 2026 – files wu 1
Gleamering_Star
#bit-truncation
 HITCON 2024 Quals 100.00 files wu 1
BeepBoop_Cryptography
#binary-encoding#decoding
 SunshineCTF 2023 34.09 files wu 1
0ff_Again_On_Aga1n
#binary-encoding#color-to-binary#image-decode
 DEADFACE 2023 – files wu 1
Barry
#bigram-substitution#cryptogram
 PatriotCTF 2022 24.52 files src wu 1
benaloh
#benaloh-cryptosystem#lcg-nonce#higher-residuosity
 DiceCTF 2021 24.82 files wu 1
LostInForest
#base64-decoding
 TrollCAT 2021 21.87 files wu 1
EasyPeasy
#base64#encoding
 Tenable 2021 22.37 files wu 1
Poly-Proof
#base-b-coefficient-recovery
 K3RN3LCTF 2021 24.37 files wu 1
Misdirection
#bacon-cipher#24-letter-alphabet
 ScriptCTF 2026 – files wu 1
mini-A3S
#affine-sbox#linear-cryptanalysis#gf3#key-recovery
 RaRCTF 2021 24.53 files wu 1
A3S
#affine-sbox#linear-cryptanalysis#gf3
 RaRCTF 2021 24.53 files wu 1
Block_construction
#aes-ecb#predictable-rng-seed
 BraekerCTF 2024 24.72 files wu 1
Blocked2
#aes-ecb#known-plaintext
 WolvCTF 2024 35.25 files wu 1
ExtremelyCoolBook
#aes-ecb#ecb-oracle#padding
 PatriotCTF 2022 24.52 files src wu 1
1-800-758-6237
#aes-ctr-nonce-reuse
 K3RN3LCTF 2021 24.37 files wu 1
CryMePlx
#aes-ctr#nonce-reuse#keystream-recovery
 CyberSecurityRumble 2022 62.00 files wu 1
DIY_enc
#aes-ctr#base64-padding-position#key-recovery
 DanteCTF 2023 24.44 files wu 1
My_BetterZED
#aes-cfb#iv-reuse#keystream-reuse
 PwnMe 2025 Quals 24.95 files wu 1
Blocked1
#aes-cbc#bit-flipping
 WolvCTF 2024 35.25 files wu 1
token
#aes#pkcs7-padding#authentication-bypass
 WRECKCTF 2022 – files wu 1
4aes
#aes#meet-in-the-middle (mitm)#bruteforce
 Defcamp 2023 Quals – files wu 1
My_Zed
#aes#iv-leaks-password#zlib#bruteforce
 PwnMe 2025 Quals 24.95 files wu 1
DIY_Crypto
#aes#custom-sbox
 Tenable 2022 22.37 files wu 1
mom_can_we_have_AES
#aes#block-cipher
 UIUCTF 2022 – files wu 1
I_Cant_Beelieve_It
#acrostic-cipher
 BxMCTF 2023 – files wu 1
TheNumbers
#a1z26
 picoCTF 2019 – files wu 1
Broken_Trust_Protocol TraceBash 2026 25.00 files wu 1
Delicious_Looking_Problem 0xFUN 2026 17.74 files wu 1
Glitched CryptoNite 2026 22.11 files wu 1
Harmonic_Cipher TraceBash 2026 25.00 files wu 1