Flare-On 7 2020 Challenge #1: Fidler

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code from fidler.py
code from password_screen() in fidler.py
>>> altered_key = 'hiptu'
>>> key = ''.join([chr(ord(x) - 1) for x in altered_key])
>>> print(key)
ghost
target_amount - 2**20 < current_coins < target_amount + 2**20
# target_amount = (2**36) + (2**35) = 103079215104
103078166528 < current_coins < 103080263680
def decode_flag(frob):
last_value = frob
encoded_flag = [1135, 1038, 1126, 1028, 1117, 1071, 1094, 1077, 1121, 1087, 1110, 1092, 1072, 1095, 1090, 1027,
1127, 1040, 1137, 1030, 1127, 1099, 1062, 1101, 1123, 1027, 1136, 1054]
decoded_flag = []
for i in range(len(encoded_flag)):
c = encoded_flag[i]
val = (c - ((i%2)*1 + (i%3)*2)) ^ last_value
decoded_flag.append(val)
last_value = c
return ''.join([chr(x) for x in decoded_flag])
>>> decode_flag(1030)
'idle_with_kitty@flare-on.com'
>>> decode_flag(1)
dle_with_kitty@flare-on.com'
flag: idle_with_kitty@flare-on.com

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Eviatar Gerzi

Eviatar Gerzi

Security researcher interested in reversing, solving CTFs, malware analysis, penetration testing and DevOps security (docker and Kubernetes)