Google CTF 2018 – Tape

TapeThe description of this challenge is: “We’ve found this priceless, old magnetic tape in our archives. We dumped the contents, but the data is corrupted and we can’t read it. We only have this old tape reader tool, but source code was lost long ago. The program has only 944 bytes, so reversing it should… Continue reading Google CTF 2018 – Tape

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Google CTF 2018 – Better Zip

The legacy ZIP crypto is long broken, so we’ve fixed it In this challenge, we are provided with a Python script (better_zip.py) that generates an encrypted zip file from an input file and key, and want to decrypt flag.zip, which was generated with this script. The script has two main parts: a BetterZipCreator class that… Continue reading Google CTF 2018 – Better Zip

Tokyo Westerns CTF 2017 – Palindromes Pairs (Challenge Phase)

This challenge was a follow-up to an earlier challenge, titled "Palindromes Pairs - Coding Phase". In that earlier warmup ppc challenge, the goal was to write an algorithm to solve the following problem: given up to 1000 strings $latex s_i$, each of length at most 1000, count the number of pairs $latex (i, j)$ such… Continue reading Tokyo Westerns CTF 2017 – Palindromes Pairs (Challenge Phase)