Crypto CTF challenges

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

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Challenges

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Challenge	CTF	Weight	Has
MMDLX #multi-layer-base64	Kashi 2025	21.78	files wu 1
Seed_of_Life #mt19937-seed-bruteforce	idekCTF 2021	24.56	files wu 1
Poker #mt19937-prediction	ImaginaryCTF 2022	24.65	files wu 1
janken_vs_kurenaif #mt19937 #seed-recovery	SECCON 2022 Quals	97.90	files wu 1
alcoholic_variety #mov-attack	hxp 2024	–	files wu 1
HAM_JAM #morse-code #codablock-barcode #vigenere	DEADFACE 2023	–	files wu 1
babynotrsa #modular-inverse	IrisCTF 2023	24.59	files wu 1
po1337nomial_revenge #mersenne-twister-untemper	L3akCTF 2026	34.47	files wu 1
otp #mersenne-twister	HSCTF 2022	–	files wu 1
Lucky_Numbers #mersenne-prime	Hack.lu 2023	94.73	files wu 1
Adventurers_Knapsack #merkle-hellman #knapsack #low-density-attack #lll (lll-lattice-reduction)	DanteCTF 2023	24.44	files wu 1
shares_v2 #meet-in-the-middle (mitm)#linear-algebra	TetCTF 2022	36.72	files wu 1
4ES #meet-in-the-middle (mitm)	CrewCTF 2024	26.89	files wu 1
Alternating_key_exchange #meet-in-the-middle (mitm)	m0leCon 2021 Quals	24.55	files wu 1
md5flow #md5-collision #unicoll #hashclash #lz4 #buffer-overflow	DamCTF 2021	24.43	files wu 1
hatmash #matrix #custom-hash #linear-algebra	UMassCTF 2022	23.56	files wu 1
fastrology #math-random-prediction #v8-xorshift #gf2-linear-algebra	PlaidCTF 2023	100.00	files wu 1
Flags #maritime-signal-flags	picoCTF 2019	–	files wu 1
encrypted_chat #many-time-pad #keystream-reuse #race-condition	TPCTF 2025	–	files wu 1
LivingWithoutExpectations #lwe-cvp	ImaginaryCTF 2022	24.65	files wu 1
Naptime #lwe #lattice	UIUCTF 2024	–	files wu 1
Let_s_Break_Something_at_LoWE_s #lwe	JerseyCTF 2025	24.73	files wu 1
Revenge_of_the_Sith #lll-lattice-attack	LakeCTF 2025 Quals	–	files wu 1
karen #lll (lll-lattice-reduction)#orthogonal-lattice #lattice	zer0pts 2022	35.97	files wu 1
trendy_windy_trigonity #lll (lll-lattice-reduction)#lattice-reduction #trigonometric-reconstruction	CyberSpace 2024	24.83	files wu 1
commitment-issues #lll (lll-lattice-reduction)#lattice #commitment-scheme	DiceCTF 2022	24.82	files wu 1
Minesweeper_2 #linear-system-solving	BITSCTF 2025	–	files wu 1
Not_So_Smooth #linear-congruence-recovery #modular-arithmetic #xor	1337UP 2023	24.23	files wu 1
shares #linear-algebra #secret-sharing	TetCTF 2022	36.72	files wu 1
Without_a_Trace #linear-algebra #matrix-trace	UIUCTF 2024	–	files wu 1
man_vs_matrix #linear-algebra #matrix-inversion #finite-field	x3ctf 2025	–	files wu 1
FaILProof #linear-algebra	SekaiCTF 2022	24.86	files wu 1
zer0lfsr #lfsr #stream-cipher-cryptanalysis #correlation-attack	0CTF 2021 Quals	–	files wu 1
rejected #lfsr #rejection-sampling #known-plaintext #gf2-linear-system	DiceCTF 2022	24.82	files wu 1
Lockpicking #lfsr #cows-and-bulls #state-recovery	DCTF 2021	–	files wu 1
correlated #lfsr #correlation-attack #filtered-lfsr	DiceCTF 2022	24.82	files wu 1
Pseudo #legendre-prng #fermat-pseudoprime	BuckeyeCTF 2021	24.81	files wu 1
adveRSAry #leaked-prime	JerseyCTF 2024	21.26	files wu 1
BabyLCG #lcg-state-recovery	L3akCTF 2026	34.47	files wu 1
luckyguess #lcg-recovery	corCTF 2022	24.92	files wu 1