Forget it, no matter how awesome looks on paper, in reality is so unpractical you are going to lose hundreds of customers. They want to pay for something and get that something fast.
There are thousands of services that offer this, starting plans at 5$ a month and you don't have to bother with hosting, availability and other bs.

PS.
In your clever explanation, you forget to mention the steps the buyer has to make for this.

And where is the file stored mister I know better than you?
You talk about decentralization like the files are stored in the blokchain...

So you're going to store the files on your computer, allow people to connect to you...and let them download the file? Is this your business model?

Rather than doing that I would simply make an order form, the buyer completes the payment to a random address and at that point, he gets the files in the mail, there are already a bunch of scripts for that.
No need for encryption, decryption, no nothing.
But we have to overcomplicate everything just to make it look cool

I believe it's one moronic thought. Fundamentally you tomb your records and the best way to get it the decoded is by sending a total to an address from which those folks take a charge? There are many approaches to anchor your records by encryption for nothing, for what reason would you pay for this?

Sometimes, I am always taken aback about the 'ingenuity' of our so called developers in on what they come up with and called a project and I believe if there is an opportunity to raise an ICO, he would surely take it and then talk about how difficult it is to get people to invest thinking they just invest in anything. Aside from the issue you raised, what if I keep my private key, and someone access it on their server which means I willingly handed over the key to my safe room to an external party which even negates the principle of blockchain that you should be the one in charge of your wallet no matter how safe the third party is making his service.

Do You accept Paypal ?? If Yes Let me Know.

Thanks.

Not really. We're working on the white paper.

Basically, POS competes across the network by a lottery ticket you get each block, for every UTXO that is older than 150 blocks. The lottery ticket is a hash and a target, the hash is made by hashing transaction ID, output numbers (so, the UTXO), a constant hash specific to our chain, so that if other chains use it, it will be different, a hash of the block 100 blocks behind the staking block, and a block height. This resulting hash is divided by the UTXO value and used in a competition to meet a specific difficulty. I borrowed some of the ideas from jl777s suggestion of using UTXOs independently and the last block staking transaction, which I used as components of the solution I implemented. Every staked block includes a no-fee staking transaction that moves the UTXO which won the competition forward, where it must sit for another 150 blocks before it can stake again.

The difficulty is managed much like PoW difficulty, but the PoS is totally relative to PoW, in that the difficulty is a function of solve time in units that are multiples of blocks passed. There are a few more details, but that's the basic POS system. To do that, it required work across numerous files, and I did it in stages.

Do you have a github PR for your POS solution ? or commit that describe well the process of integration of your Proof Of Stake ? I got an eye on the commits but can't figure out it ... any PR or anything clear please ?

Block size does not affect the block generation time. The block generation time is 2.5m and Block max size 8MB