Hmmm first we have to hunt some hints :
1) A file with a .ppm extention
2) "" Hi! Welcome to esoteric programming! ""
3) "" The encrypted pass is: EPCQFBXKWURQCTXOIPMN ""
Well , w're going to ask google , to get some help :D
So , after searching and learning about esoteric programming language , and read some articls about ppm files , i asked google about " esoteric programming ppm " , then i got this https://www.bertnase.de/npiet/ , hmmmmmm.
And now i know what i really will do with this : https://www.bertnase.de/npiet/npiet-1.3a-win32.zip
Check this picture :
Hmmm we have now a key "EYJFRGTT" to decrypt something...
Maybe to decrypt "EPCQFBXKWURQCTXOIPMN" , it seems like a "cipher vigenere"
I w'll try and see the result :D !
Message : " EPCQFBXKWURQCTXOIPMNV "
Key of encryption : " EYJFRGTT "
Result : " ARTLOVERSWILLNEVERDIE "
hell yeah , that's our flag : ARTLOVERSWILLNEVERDIE
g00d bye <3