cryptomedium

Blum-blum-shub

spbctf

Task: Break BBS PRNG with weak seed (1-100000) to decrypt multiple sequentially encrypted files. Solution: Brute-force seed using known PNG header as plaintext verification, then decrypt the flag file.

$ ls tags/ techniques/
brute_forceprngbbsblum_blum_shubweak_seed
seed_brute_forceknown_plaintext_verificationbbs_state_recovery
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