This task some harder than other reverse task in this competition, but it has a really simple decision.
1. Open IDA or other Disassembler to analyse source code; 1.1 If you have troubles with checking function in main(IDA only), change the borders of functions in the function and end it up to main function;2. You can see the part of flag: "picoCTF{br1ng_y0ur_0wn_k3y";3. Other symbols encrypted, we see a lot of codelines. Try to write reverse programm, but what is MD5?;4. This cryptography function available to us in cryptography library;5. Write reverse programm and start it with gcc programm.c -o programm.exe -lcrypto; 