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
rolling-in-the-mud #pigpen-cipher	LA 2023	–	files wu 2
Backup #pcap-analysis #ftp-credential-sniffing #protected-zip-extraction	CyberSecurityRumble 2023 Quals	24.80	files wu 2
Hashcrack101 #password-hash-cracking	BSidesSF 2021	23.94	files wu 2
Rock_my_Password #password-cracking #rockyou	SwampCTF 2025	40.40	files wu 2
babypad #padding-oracle #aes-ctr	corCTF 2021	24.92	files wu 2
restricted_oracle #padding-oracle	GPN 2025	–	files wu 2
Unbreakable_Encryption #otp-key-reuse	MetaCTF 2021	–	files wu 2
Cipher_Mishap #octal-to-ascii-decoding	BCACTF 2021	–	files wu 2
ot_or_not_ot #oblivious-transfer #legendre-symbol #aes-cbc	zer0pts 2021	24.56	files wu 2
Non-Square_Freedom_1 #non-squarefree-rsa	K3RN3LCTF 2021	24.37	files wu 2
Non-Square_Freedom_2 #non-squarefree-rsa	K3RN3LCTF 2021	24.37	files wu 2
MPKC #multivariate-crypto #linear-part-recovery #groebner-basis	PlaidCTF 2020	93.15	files wu 2
Lines #multiplicative-cipher	ImaginaryCTF 2021	–	files wu 2
What_next #mt19937-prediction	Mapna 2024	24.59	files wu 2
twist_and_shout #mt19937 #state-recovery #untwist	Zh3r0 2021	–	files src wu 2
real_mersenne #mt19937 #state-recovery #float-prediction	Zh3r0 2021	–	files src wu 2
MaaS #modulus-recovery-oracle	n00bzCTF 2023	15.12	files wu 2
Cards_Galore #mirdek-cipher #caesar-cipher	UMDCTF 2021	–	files wu 2
MeetMeInMiddle #meet-in-the-middle (mitm)	OFPPT 2022	–	files wu 2
MDLP #matrix-discrete-logarithm #linear-algebra-cryptanalysis	ASIS 2021 Finals	89.22	files wu 2
Art_Class #maritime-signal-flags #visual-decoding	UMDCTF 2021	–	files wu 2
Three-Time_Pad #many-time-pad #key-reuse	UIUCTF 2023	–	files src wu 2
Polyphenol #lll (lll-lattice-reduction)	idekCTF 2021	24.56	files wu 2
Just_One_More #linear-system	NahamCon 2023	34.82	files wu 2
rps_casino #lfsr #gf2-linear-system #z3 #state-recovery	DiceCTF 2024 Quals	54.40	files wu 2
Obscurity #lfsr	m0leCon 2021 Quals	24.55	files wu 2
lwsr #lfsr	Hack.lu 2021	94.48	files wu 2
nanothorpe #length-extension	hxp 2020	94.00	files wu 2
Delegate-wallet #lcg-prng-prediction #weak-randomness	0x41414141 2021	–	files wu 2
tadpole #lcg #modulus-recovery	corCTF 2022	24.92	files wu 2
one-more-time-pad #known-plaintext-xor	LA 2023	–	files wu 2
XOR #known-plaintext-xor	OFPPT 2022	–	files wu 2
yor #known-plaintext	hxp 2022	–	files wu 2
opisthocomus-hoazin #known-plaintext	HSCTF 2021	–	files src wu 2
Knapsack #knapsack #meet-in-the-middle (mitm)	BackdoorCTF 2023	–	files wu 2
why_is_a_raven #isogeny #sidh #torsion-point-attack	Union 2021	24.34	files wu 2
hyper #hyperelliptic-curve	hxp 2020	94.00	files wu 2
payback #http-parameter-pollution #duplicate-parameter #logic-flaw	CyberSecurityRumble 2021	41.60	files wu 2
Duality #hmac-key-length-collision	justCTF 2024 Quals	77.17	files wu 2
queen-of-the-hill #hill-cipher	HSCTF 2021	–	files src wu 2