Cryptanalysis

Hello,
I am stuck on this challenge
Statement

A friend of yours has received a strange file containing a random sequence of zeros and ones. Prove to him that all this is not as random as it seems by bringing back the flag!

sha256 checksum of the file :
2c1ebdcc5bcf58b2e97fa58d5559025a7210b81a94fdedfa6e7ec151d9b29d18

I downloaded the given file and verified the checksum, it verifies correctly
% sha256sum ch64.txt
2c1ebdcc5bcf58b2e97fa58d5559025a7210b81a94fdedfa6e7ec151d9b29d18 ch64.txt

Anyone have a hint on what I should consider next?
Thank you