Osce fc4me

I’ve been looking at this challenge and have come at an end. Would anyone help me understand the rest of the challenge I couldn’t complete? I want to know how far off I am and if I was close at all :P, so far I’ve gotten to:

Email: ****** , Registration Code: ***** | Now decode your CTP Secret Key and you are done! :

Spoiler Removed

Try harder.

@s1gnal

I like it, haha

anyone here to recommend on what to study to actually crack the secret key? i tried it with obvious methods but failed. What i have to know to crack?