Points: 300

Tags: crypto 

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We designed our own proprietary cipher, called Blobfish. We were very proud of it, until someone mounted a chosen-plaintext attack on the cipher, and sent the master key to us. He requested a large amount of money to show us the weakness in Blobfish. Fortunately, we have the queries (plaintexts) he made to our system, as well as the responses (ciphertexts).

Our CEO decided to hire someone less greedy to help us redesign Blobfish. But he must first prove he is worthy. Look at the log, and the cipher design. If you can find the master key, use the function `make_flag()` on it to generate the flag. Send us the flag, and we'll get back to you for further negotiations.

PS: `make_flag()` is defined at the end of Blobfish.py.


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