So we run bruteforce first on the outer layer - to decode Blowfish and take all proper base64 results as potential hits.Īnd then we take those results and try to decode them with DES to look for the flag. We also know that both keys are in the range 0-9999999. So what we have here is the encrypted flag:ĪiEjLYxiRUlgG+OYaYje5HOwvS8UFegdXRrCsIiy6pBH67fDvGbLF/gtZihyW7WYVOrsi7/N1sgaVUBU/VW1NwEOrOhguZZfP5T7Gw88sMx9KFepLfsjOLPKKVUuMbVu6Lno0FJjbU+7ft1VtdsQhAh1Lc91SDcduoI3J1FwffwwEwy1L7FKjg14LZ9fgaMF5c43T8avL+bpOBDFHiPzK1Mwv4ftVt6k5UV13cPV3VLm+Jx7Q/7LLamyQLLUU0O1pcKZOHi7oYPngpFh7VmIPIJwCsmoCAyt8+圜/uqNgpfUoD0SHfG7tvz7F8sZKL6RfezLvFN++8B+rs+6AGOiSHCmnGbO4PNcOdZfWP4lYZQRIZ/DTN4ntg=Īnd we know that the flag was encrypted first with DES with padding, the data were transformed into base64 and this was encrypted again with Blowfish with padding and it was encoded as base64. It doesn't make the task any "harder", only more annoying. Seriously, there is no need to make a task where bruteforce is taking minutes to run on 8 paralell cores. * The calculations for this task were a bit time consuming due to key universum size. This suggested a meet-in-the-middle attack using this payload, which was not a good approach, because the example payload was encrypted with different keys than the flag. * The authors for no apparent reason have given an example payload apart from the flag.
This website was adding random paddings and without knowing about it, there was no way to solve it. * Authors used some shady website for encryption and not the ciphers directly. The general idea was simple - the authors used double encryption with DES and Blowfish and the task was to decode the message.
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