YCTF

Strive Marish Leadman TypeCDR by glys

2024-09-30(1 min. read) - crypto

Description

Looks like primo hex garbage. Maybe something went wrong? Can you make sense of it?


Upon connecting to the service we get rsa values. These are different on each connect.

   huntress nc challenge.ctf.games 30814
p: 0xc6eb6997016d204b540c1da50e5ff68b0ffaa565a3a8594e2f227f4d5b94070c27c16ce1d5d71ee4cca71b7931f02ad4d25f4e215c9f7588c247e996b93c80df
q: 0xc6b8954f39801616c9b450018a9618a3d60517e0a13e7f1705a698813be6bd77b50a38f74375009e7caca951e659f81915e31bb80edd0a5cd40379937fafd435
d: 0x44e781a1688bae70205dca67f6ac955f73572191b72ba02e14be2d9d7ac848c3c1f7ec3deb3ed855e67b6bec28815eef95a0611cd46407246a33068f3880591705332d0b16f9eedf49a7ba97db87211faf7ac1ee20c5534704dcb9a3f6c27c0140b0e002c5426838ac40239d16067b9da49f45e63c9b07ebe0d44563b640e6b9
e: 0x10001
n: 0x9a6980e3436bd838c879983ff22c8e707d8cb8fd3b4857d4d5cd0e96dd146697cb5ecffc24d78bb927be8b3b4ac735d59ead4224ef9ca8e103df7a677a2bb1d0267b1318a6ba5146bf8b9378bac242d1bae426c7f15eaa5aaf801e4caa405389d46d9ade2da4715570649e4781d1d2c83bd46286e75ebdea5f8638f22db05a2b

0x73b0be69adc7244a161074be4d3105ecbce644ce2c433bc470111fd9d2c3e5b59f7c8297871d62001b97f12d0fdd74ecef60b4c07d2d0f3f41963704ff806c5e3143df79ef093eb5a8d12e9fb86acef7a16cb243c8ed3954720c3b6d0e9107a864317799192e41dad077b042d6d0a58573485b9162a156a3e2b3e2b61ac5f13f

Decrypting the bottom number with a python script always gives

13040004482825409713878684097082783294385439409007049196036599611841074762489249861841795197

Following logicfrom article linked in challenge prompt we decode as bytes

num = 13040004482825409713878684097082783294385439409007049196036599611841074762489249861841795197

msg = []
while num > 0:
    out = num % 256
    num = num // 256

    msg = [chr(out)] + msg

print(''.join(msg))