Rotation

Challenge

My new rotor messed up the flag!

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96a_abL_?b04c?0Cbc50C_E_C03c4<HcC5DN

I tried to decode it, but it didn’t work. The rotor must have been too fast!

Solution

We suspect a rotation cipher because of the cipher, and assuming the given string starts with he2023, this indeed checks out (h and e are 3 apart in the ASCII table, so are 9 and 6). It would appear to be a rotation of 47, though sometimes it is +47, sometimes -47, so we write a short script to find the direction of rotation

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import string

ct="96a_abL_?b04c?0Cbc50C_E_C03c4<HcC5DN"
flag = ""

for i in range(0,len(ct)):
  pt = chr ( ord(ct[i])+47 )
  if pt not in string.printable:
     pt = chr ( ord(ct[i])-47 )

  flag += pt

print(flag)

which gives us the flag!

Flag