Checksums as network transmission validation work with certainty until light speed is breached by technology

Keep adding known strings to positions in the files infinitely and breach the required energy amounts of as many stars (or reactors) as you would need to in order to prove that the latency of the communication between each of those sources (communication by light or by objects containing data moving faster than light if it doesn’t shred apart) is longer than the time period of the communication link between you and the verifying party (or TLS certificate validity period of 1 year).

That’s the truth of checksums, you would be able to interleave strings at each position in the file and send those as a new checksum to verify anything beyond energy and the speed of communication between the energy source of the computers trying to create a collision in that time period.

FILE AAAA

SHA256 = $n

FILE AAAA

SHA256 with string “asdfhjgfdjk” after each byte = $nn

Or until everything is instant, literally.