Sigma [crypto]

Sigma

Crack this.

We're given the following:

10320831141252164475480592397410881183128414021520157116851780189419421991209921942315241625302578269728072902300131153236334834643575368637343782389340044129

Recon

First three digits is 103 which is 'g', next one is 208, which is the previous one + the next character 108 aka 'i', repeat :-)

Code

n = [103, 208, 311, 412, 521, 644, 754, 805, 923, 974, 1088, 1183, 1284, 1402, 1520, 1571, 1685, 1780, 1894, 1942, 1991, 2099, 2194, 2315, 2416, 2530, 2578, 2697, 2807, 2902, 3001, 3115, 3236, 3348, 3464, 3575, 3686, 3734, 3782, 3893, 4004, 4129]
p = ''
i = 0

for x in n:
    p += chr(x - i)
    i = x

print(p)

Flag

gigem{n3v3r_evv3r_r01l_yer0wn_cryptoo00oo}