Write-up – Crypto 100 – Sam Sepiol’s pizzas

Points: 100
Author: dok
Description: How much do you love pizza ?
Remarks : “there are some guessing…”


During GreHack 2016, crypto challenge Sam Sepiol’s Pizzas was based on the following image:

We can see different things within this menu:

– Theme is Italy, with a background of a coliseum.
– Available Pizzas are various with indices (9), prices and description.
– There is multiple handwritten elements with a blue marker.

From this point, we can try to understand the following question:
“unirlbhznqrlbhepubvpr?”

After several tries, we found that the following string was encoded using ROT13.
Knowing that, reversing it was easy, but it only lead us to the following translation:
“haveyoumadeyourchoice?”

That’s not a big improvement that seems to lead to any solution…

After that, we looked into the different numbers written down in blue:

1.11-7.24-1.0-6.0-Ø123
6.29-9.5-9.26-5.26-Ø48
1.0-2.3-5.0-2.22-9.15-5.2-1.7
8.20-1.5-Ø125

What we guessed:

– Ø123 and Ø125 codes are ASCII equivalent of { and } characters, Ø48 is 0
– First numbers of each separated values seems to be a reference pizzas indices
– Second numbers of each separated values seems to be a reference to a character position

From this, we found a weird translation with non-sense:
TU16{fncv01i5uhatel}

We then tried to apply ROT13 on it (first part was a clue !) and finally found the final flag !

GH16{sapi01v5hungry}

1 thought on “Write-up – Crypto 100 – Sam Sepiol’s pizzas

  1. Viand0x Reply

    Lots of guessing actually…

    This kind of challenges drives me nuts after 2am
    haha 😀

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