Cipher Tech Solutions Forensic Software interview questions

Applied through indeed recruiter reached out with a coding challenge. Challenge was broken into 3 parts the first part was to implement LSFR encryption algorithm, second part was to extract data from a custom file and decrypt it using your LSFR algorithm, third part was to use the second algorithm with a sample input file in order to decrypt the magic bytes which were used in another sample input file to uncover jpeg images with secret messages. Took me some time to research because I had very limited experience with encryption and hex programming. I got a response that I did not score high enough, however my code did pass their sample inputs. The project was very interesting however, I feel that it required too much effort and time just to get an actual interview, especially considering that their scoring method seems to be very rigorous.