-snip-
Are we taking privacy seriously over here? What if I happen to log in to my bank account and it's capturing every single details on the screen?
Its just hashes. While this was my first though, its not an issue as long as the hashing function used is not broken. It might be broken some time in the funture but even then the information of the hash is not enough to reverse it to a full picture. E.g. 1024*768*16 bit = 12MiB, while SHA512 would only give you 512 bits of information. There is no chance to reverse the process to a full picture, too much information is lost.
This is also the reason why this is no "quantum state" of anything, but just a very large collection of hashes that serve no purpose other than bloating up the blockchain. This might be used as rainbow table, but I doubt even thats possible.
I just didn't understand what was meant as inserting a hash of everyones's computers activity periodically doesn't add much at all to the size of the blockchain. Almost zero change to the size.
I have no idea what your idea of "almost zero change to the size" and "periodically" is, but lets assume:
- once a day
- only a screenshot, no other data
- MD2 (128 bit)
- 10,000 paricipants
Thats 128*10,000 = 1250KiB daily of information. You are basically removing littel more than a full bitcoin block each day, for every 10k screenshots with a 128 bit hash.