SharifCTF 7 – Lobotomized LSB Oracle

[Note: this is a follow up to the challenge LSB Oracle. It may be useful to view the writeup for that challenge first.] In LSB Oracle, we were given an oracle that would compute the least significant bit of decryptions of inputs we feed it. In Lobotomized LSB Oracle, we are given the same oracle,… Continue reading SharifCTF 7 – Lobotomized LSB Oracle

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SharifCTF 7 – Radio Intelligence

This crypto challenge was somewhat strange in that it took the form of a scrambled audio file. The challenge description tells us the file was formed by taking an audio recording of someone speaking (specifically, saying "The flag is", pausing for 1-2 seconds, and then reading out the flag) XORed with a linear-feedback shift register.… Continue reading SharifCTF 7 – Radio Intelligence

SharifCTF 7 – Bsniff

Bsniff was a packet capture file consisting of DNS requests to blockchain.info and GET requests of the form blockchain.info/q/addressbalance/[bitcoin address]?confirmations=6. Here is a Wireshark screenshot with those things: Looking at the HTTP packet details, we can see that the User-Agent is python-requests, suggesting that this pcap basically consists of a Python script making requests to… Continue reading SharifCTF 7 – Bsniff