CTF challenges & writeups

31 challenges in family ⊕ crypto:stream-cipher ✕ clear · browse all techniques

Challenge	CTF	Weight	Category	Has
Dont_unpack_me #rc4 #pe-unpacking	Bhackari 2026	–	Reverse	files wu 1
encrypted_chat #many-time-pad #keystream-reuse #race-condition	TPCTF 2025	–	Crypto	files wu 1
rps_casino #lfsr #gf2-linear-system #z3 #state-recovery	DiceCTF 2024 Quals	54.40	Crypto	files wu 2
my_array_generator #keystream-recovery	DownUnderCTF 2024	68.04	Crypto	files src wu 1
DHCPPP #chacha20-poly1305 #nonce-reuse #tag-forgery	PlaidCTF 2024	95.19	Misc	files wu 1
HaRlEm_ShAkE #chacha20-poly1305	hxp 2024	–	Reverse	files wu 1
Blue_Office #lcg-keystream #seed-bruteforce #known-plaintext	Crypto 2023	59.60	Misc	files wu 1
the-other-css #z3 #lfsr #css-cipher	PlaidCTF 2023	100.00	Crypto	files wu 1
BabyRC4 #rc4 #keystream-reuse	SEETF 2023	–	Crypto	files wu 1
Streamer #stream-cipher #bruteforce	TSG 2023	–	Crypto	files wu 3
decompile_me #rc4 #reversing #keystream	zer0pts 2023	52.62	Reverse	files wu 1
BinomialWays #reversible-stream-cipher #modular-addition	1337UP 2022	22.49	Crypto	files wu 2
correlated #lfsr #correlation-attack #filtered-lfsr	DiceCTF 2022	24.82	Crypto	files wu 1
rejected #lfsr #rejection-sampling #known-plaintext #gf2-linear-system	DiceCTF 2022	24.82	Crypto	files wu 1
would-you-wordle #rc4	JerseyCTF 2022	25.00	Crypto	files wu 1
TimeCapsule #stream-cipher #keystream-recovery #permutation-bruteforce	SekaiCTF 2022	24.86	Crypto	files wu 3
ransomwaRE #malware-reversing #date-seeded-key #aes-ctr #keystream-reuse	CSAW 2021 Quals	20.54	Reverse	files wu 2
lwsr #lfsr	Hack.lu 2021	94.48	Crypto	files wu 2
Cookie_Stream #stream-cipher-bitflip	ImaginaryCTF 2021	–	Web	files wu 1
Revvy_Chevy #lcg-keystream	MetaCTF 2021	–	Reverse	files wu 1
malware #aes-ctr #known-plaintext #keystream-reuse	UMassCTF 2021	23.56	Crypto	files wu 3
Obscurity #lfsr	m0leCon 2021 Quals	24.55	Crypto	files wu 2
My_BetterZED #aes-cfb #iv-reuse #keystream-reuse	PwnMe 2025 Quals	24.95	Crypto	files wu 1
Real_Smooth #stream-cipher #known-plaintext	BuckeyeCTF 2023	34.50	Crypto	files wu 2
Lightbulb #android #apk-reversing #rc4 #java	CyberSecurityRumble 2023 Quals	24.80	Reverse	files wu 1
Scrambled_Pizzeria #known-plaintext #keystream-recovery	TeamItaly 2023	24.88	Crypto	files wu 1
CryMePlx #aes-ctr #nonce-reuse #keystream-recovery	CyberSecurityRumble 2022	62.00	Crypto	files wu 1
zer0lfsr #lfsr #stream-cipher-cryptanalysis #correlation-attack	0CTF 2021 Quals	–	Crypto	files wu 1
Lockpicking #lfsr #cows-and-bulls #state-recovery	DCTF 2021	–	Crypto	files wu 1
Tabula_Recta #rc4-fms	InCTF 2021	70.41	Crypto	files wu 1
Game_of_Secrets #cellular-automata-keystream	K3RN3LCTF 2021	24.37	Crypto	files wu 1

Challenges