cryptohard

Thousands of RNGs

kalmarctf

Task: 3500 LFSRs over GF(2) with known irreducible polynomials XOR-combined into 6.8M bit stream, need to recover states to decrypt AES-ECB flag. Solution: Partial fraction decomposition using product tree and remainder tree with derivative trick for fast modular arithmetic.

$ ls tags/ techniques/
stream_ciphergf2lfsraes_ecbpolynomial_arithmeticirreducible_polynomials
partial_fraction_decompositionproduct_treeremainder_treederivative_trickpower_series_inverse
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