Type: crypto / stego
Find flag in the image (PTOT_1d23c8694e5cf6727b9ed21285a0d61f)!
Google images is your friend and you will quickly find some interesting links like this one for example:
So PTOT stands for Periodic Table Of Typefaces. You can notice in the challenge image that some typefaces are in the wrong place, and some appear 2 or 3 times…
So let’s spot the differences (
original rank ⇢ crypto rank | crypto symbol):
There is 45 differences which is a bit longer than the usual ‘
ASIS_md5()‘ flag which is 37 chars length. After numerous tries, we noticed something. If we concat all these numbers, convert them to hex value and then decode the hex string to plain ASCII we have a 36 chars length string… ending with something like md5 values ‘
H=format(324878083202626694117443567177148322190861294622618211941523751741739958462509854242915, 'x') print H.decode("hex") >>> ?;??d?hI<q"Cv?f?%?,??/¦38???ca808c
Wondering where were the missing bytes, i noticed in the differences table that there was three 1-digit numbers. Appending a leading
0 to these numbers (except the first one to avoid python octal conversion), the hex value would give a 37 chars length string which is the final flag!
H=format(32487808320262606941174435671771483220190861294622618211941523751741739958462509854242915, 'x') print H.decode("hex") >>> ASIS_c9a1cd21db5d38923562fccabbca808c