The solution for the "ELF x64 - Crackme automating" /"ELF x64 - Automatisation du crackme" proposed by "0xmitsurugi" on root-me.org. Keep trying before looking !
Here you have to extract in a separate file manually the blocks that generate the key, and then pass this file in parameter to "parseur.cpp"
The file that are given to parseur.cpp should be in a predefined format, as in the file "ch302_dis",
also not that before calling the Base64 converter, you have to get read of the white caracters present
in the output file of parseur.cpp