26
Apr
2013

pCTF 2013 – compression (crypto 250)

In this challenge we are given a very simple python service to connect to. In a loop, it reads some data from the client, appends a flag to it, compresses it, encrypts it with AES in CTR mode, and then returns it to the client. The goal is to find the flag, of course!

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22
Apr
2013

pCTF 2013 – cyrpto (crypto 100)

One of us devised a new cryptosystem! Can you break it?

For this challenge we had access to a home-grown crypto system, allowing us to encrypt and decrypt messages. However the server refused to decrypt the encrypted flag given.

Let’s see if we can trick it.
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