Find The Secret Flag

Hi guys, i’m having problems to find what this binary needs. I tried every single way I learn until now to print what it need but with no success!
I get a hash prompted on CLI (gdb) but could’t use it.
I couldn’t find what to insert on /tmp/secret.
Could someone please help me (probably more like guiding through) solve this challenge.
Any help will be welcome.

Thanks in advance!