To open a Secret Container you need to find a gray paper sheet near it, and translate code from Klingon language (Star Trek):

1 – Wa'
2 – cha'
3 – wej
4 – loS
5 – vagH
6 – jav
7 – Soch
8 – chorgh
9 – Hut
0 – pagH

i found codes here:
https://cs2bus.com/sharedfiles/filedetails/?id=1960849971