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
Strong_password #zip-cracking #zip2john #john	DCTF 2021	–	files wu 3
xorsa #xor-leak-factoring #bit-by-bit-factoring #rsa	PlaidCTF 2021	99.64	files wu 3
XORROX #xor-keystream-reversal	NahamCon 2022	24.61	files wu 3
Ciphper #xor	TAMUctf 2021	–	files wu 3
Perfect_XOR #xor	HacktivityCon 2021	–	files wu 3
winter #winternitz #hash-based-signature #key-reuse #forgery	DiceCTF 2024 Quals	54.40	files wu 3
Warmup #visual-cryptography	TMUCTF 2021	–	files wu 3
Vinegar #vigenere-cipher	n00bzCTF 2024	24.23	files wu 3
Code_Decode #substitution-cipher #embedded-key	DeconstruCT.F 2021	19.69	files wu 3
Substitution #substitution-cipher #atbash	DaVinciCTF 2021	24.50	files wu 3
Substitution_Cipher_I #substitution-cipher	DownUnderCTF 2021	–	files src wu 3
TimeCapsule #stream-cipher #keystream-recovery #permutation-bruteforce	SekaiCTF 2022	24.86	files wu 3
Streamer #stream-cipher #bruteforce	TSG 2023	–	files wu 3
xorpals #single-byte-xor #bruteforce	DamCTF 2021	24.43	files wu 3
sidhe #sidh #adaptive-key-recovery #static-key-reuse	PlaidCTF 2020	93.15	files wu 3
Unimod #shift-cipher-bruteforce	NahamCon 2022	24.61	files wu 3
RSA_Outro #rsa-related-primes	NahamCon 2023	34.82	files wu 3
Size_Matters #rsa-factorization	MetaCTF 2021	–	files wu 3
babycrypto3 #rsa-cm-factorization	LINE 2021	–	files wu 3
RSA-3 #rsa #wiener-attack	DeconstruCT.F 2021	19.69	files wu 3
Really_Secure_Algorithm #rsa #wiener-attack	DawgCTF 2021	23.29	files wu 3
Easy_RSA #rsa #textbook-decryption	BCACTF 2021	–	files wu 3
4096 #rsa #smooth-modulus-factorization	corCTF 2021	24.92	files wu 3
Risk_Security_Analyst_Alice_Vs_Eve #rsa #shared-modulus #factor-n-via-d	darkCON 2021	24.06	files wu 3
RSA-1 #rsa #rsactftool #small-factor	DeconstruCT.F 2021	19.69	files wu 3
Complicated_Function #rsa #partial-key-exposure #coppersmith	TSG 2023	–	files wu 3
Bits #rsa #lsb-oracle #discrete-log #binary-search-factoring	CSAW 2021 Quals	20.54	files wu 3
BootlessRSA #rsa #low-exponent #cube-root	DaVinciCTF 2021	24.50	files wu 3
RSA-2 #rsa #low-exponent #cube-root	DeconstruCT.F 2021	19.69	files wu 3
warsamup #rsa #franklin-reiter #related-message	zer0pts 2021	24.56	files wu 3
close_enough #rsa #fermat-factorization #close-primes	SEETF 2022	–	files wu 3
anti_fermat #rsa #factorization #known-sum #bit-complement	zer0pts 2022	35.97	files wu 3
Basic_RSA #rsa #factorization	TAMUctf 2021	–	files wu 3
The_Obligatory_RSA_Challenge #rsa #factordb	DawgCTF 2021	23.29	files wu 3
eazy-RSA #rsa #e-and-phi-not-coprime #modular-square-root #crt	0x41414141 2021	–	files wu 3
Unique_Flag #rsa #character-oracle #tree-search	TSG 2023	–	files wu 3
CaesarMirror #rot13	HacktivityCon 2021	–	files wu 3
repeat #repeating-key-xor	UofTCTF 2024	23.90	files wu 3
h4XOR #repeating-key-xor	HeroCTF 2021	35.17	files wu 3
guess-the-bit #quadratic-residue-distinguisher	LA 2023	–	files wu 3