Block cipher challenge

Level: CTR mode

Sorry, you're not an admin (need is_admin: true)



Ciphertext (hexencoded), for easy copy-paste

838f87f64dbd027a26f7af760eff634d7b3d76855175002dc51779962155ab6680a4816478bbb4d0d68580399beaf913a37fec0f9721de25a364f667398e2ddb

Ciphertext (hexencoded):

838f87f64dbd027a26f7af760eff634d 7b3d76855175002dc51779962155ab66 80a4816478bbb4d0d68580399beaf913 a37fec0f9721de25a364f667398e2ddb

Plaintext (hexencoded):

838f87f64dbd027a26f7af760eff634d 7b22757365726e616d65223a20226775 657374222c202269735f677565737422 3a20747275657d090909090909090909

Plaintext:

\x83\x8f\x87\xf6M\xbd\x02z&\xf7\xafv\x0e\xffcM {"username": "gu est", "is_guest" : true}\t\t\t\t\t\t\t\t\t

Final plaintext

{"username": "guest", "is_guest": true}