Challenge Name:
Cyberkok Eksklusiv opskrift
Category:
Kom godt i gang
Challenge Description:
Vi tror, at vores berømte cyberkok har været lidt for dybt i julesnapsen.
Vi har i hvert fald modtaget følgende besked, men vi kan slet ikke tyde den:
Nu er det jul igen! Her er en meget EKSKLUSIV opskrift!
XOXOXO
+----------------------+
| JULEMAD |
+----------------------+
| 04 16 7f 3e 2c 29 69 |
| 2e 30 22 68 2a 2d 25 |
| 2e 30 61 2f 38 2d 21 |
| 3e 3c 28 68 20 20 2a |
| 67 37 20 2c 3b 24 36 |
| 67 26 a9 68 2a 2d 25 |
| 2e 74 31 |
+----------------------+
Approach
So yet again the “Cyberchef” has tried out some new cipher “recipe”… As described in Cyberkok Hekseri it is a good idea to pay close attention to both the title and the description. “Ekslusiv opskrift”, translated from Danish means “Exclusive recipe”, where exclusive might illude to the concept of XOR, which is short for “Exclusive or”!
Seeing as the input is hexadecimals and we know that the expected flag output is text, we just need the key, which should be used for the XOR operation.
If we pay close attention to the calendar, we see in the top, where one would expect the month to be stated, that the word “JULEMAD” (meaning Christmas food) is written, which seems a bit “out of place”. Working of the notion that every bit of information can be important we try out the key JULEMAD as our XOR key.
Using the following Cyberchef recipe we manage to get the flag!
Flag
NC3{ah-den-glade-juletid-man-bliver-så-glad!}