CTF challenges & writeups

88 challenges in family ⊕ crypto:number-theory ✕ clear · browse all techniques

Challenge	CTF	Weight	Category	Has
shares_v2 #meet-in-the-middle (mitm)#linear-algebra	TetCTF 2022	36.72	Crypto	files wu 1
hatmash #matrix #custom-hash #linear-algebra	UMassCTF 2022	23.56	Crypto	files wu 1
FailedHashFunction #custom-hash #bit-manipulation	UTCTF 2022	–	Crypto	files wu 2
Sunset #subset-sum #convolution	UTCTF 2022	–	Crypto	files wu 2
Uzumaki #reversing #modular-arithmetic	VishwaCTF 2022	20.79	Reverse	files wu 1
fancynotes #hash-length-extension	m0leCon 2022 Quals	36.00	Crypto	files wu 2
mathhash #custom-hash #floating-point #byte-by-byte-bruteforce	zer0pts 2022	35.97	Crypto	files wu 1
MDLP #matrix-discrete-logarithm #linear-algebra-cryptanalysis	ASIS 2021 Finals	89.22	Crypto	files wu 2
Crack_Me #hash-cracking #salted-sha256 #hashcat	CSAW 2021 Quals	20.54	Crypto	files wu 3
Onlude #lu-decomposition #matrix-algebra-gf-p	Crypto 2021	36.00	Misc	files wu 1
frozen #signature-forgery #masked-key-recovery #modular-inverse	Crypto 2021	36.00	Misc	files wu 1
hyper_normal #modular-linear-scheme #per-column-bruteforce	Crypto 2021	36.00	Misc	files wu 2
CrackMe #reversing #hash-byte-reversal #hashcat	DaVinciCTF 2021	24.50	Reverse	files wu 3
TrashChain #custom-hash-collision #multiplicative-hash #modular-arithmetic	DawgCTF 2021	23.29	Crypto	files wu 3
signature-sheep-scheming-signature-schemes #lattice-signature #mask-recovery	DiceCTF 2021	24.82	Crypto	files wu 1
Substitution_Cipher_II #lagrange-interpolation	DownUnderCTF 2021	–	Crypto	files wu 1
treasure #shamir-secret-sharing	DownUnderCTF 2021	–	Crypto	files wu 1
silver-water-industries #quadratic-residue	Hack.lu 2021	94.48	Crypto	files wu 3
Wrong_Way_on_a_One_Way_Street #hash-cracking	MetaCTF 2021	–	Crypto	files wu 3
leaky_block_cipher #small-multiplicative-order #polynomial-factorization	PlaidCTF 2021	99.64	Crypto	files wu 2
RITSEC_Hash #custom-hash #bruteforce #rockyou	RITSEC 2021	–	Crypto	files wu 2
JAM #hash-length-extension #md5	TFC 2021	–	Crypto	files wu 1
dividing_secrets #discrete-log #quadratic-residue	corCTF 2021	24.92	Crypto	files wu 2
Nameless #sum-of-squares-rsa	idekCTF 2021	24.56	Crypto	files wu 2
janken_vs_yoshiking #elgamal #quadratic-residue #legendre-symbol	zer0pts 2021	24.56	Crypto	files wu 2
ot_or_not_ot #oblivious-transfer #legendre-symbol #aes-cbc	zer0pts 2021	24.56	Crypto	files wu 2
minithorpe #hash-reversal	hxp 2020	94.00	Crypto	files wu 1
nobranch7e4 #linear-algebra	hxp 2020	94.00	Reverse	files wu 1
octothorpe #hash-collision	hxp 2020	94.00	Crypto	files wu 1
SuperSecureVault #crt #modular-arithmetic	Pragyan 2019	20.69	Misc	files wu 1
Revenge_of_the_Sith #lll-lattice-attack	LakeCTF 2025 Quals	–	Crypto	files wu 1
grammar_nazi #rsa-polynomial-root-recovery	MaltaCTF 2025 Quals	24.95	Crypto	files wu 1
Mirror_Hash #custom-hash #birthday-attack #subset-sum #hash-collision	PwnMe 2025 Quals	24.95	Crypto	files wu 1
Vending_Machine #ecdsa #biased-nonce #signature-malleability #python-hash-collision #lattice	PwnMe 2025 Quals	24.95	Crypto	files wu 1
trendy_windy_trigonity #lll (lll-lattice-reduction)#lattice-reduction #trigonometric-reconstruction	CyberSpace 2024	24.83	Crypto	files wu 1
breakfaest #fiat-shamir-forgery	KalmarCTF 2024	24.21	Crypto	files wu 1
Admin_CLI #hash-collision	FE-CTF 2023	–	Misc	files wu 1
Subarray_Sums_101 #subset-sum #z3	TeamItaly 2023	24.88	Misc	files wu 1
eazy-RSA #rsa #e-and-phi-not-coprime #modular-square-root #crt	0x41414141 2021	–	Crypto	files wu 3
SMS #custom-hash-collision #substitute-mix-shift	3kCTF 2021	24.14	Crypto	files wu 1

Challenges