New concept of alt-coin

I'm thinking about a new concept of cryptocoin.
The block validation of this new coin will be very fast (5seconds).
To manage this the validation wouldn't work with a proof of work but with a signature system based on an existing cryptocurrency.
For example if you have 2BTC you will sign a block with your address and the block with the hugest amount of signed BTC value will win.
The people who have signed the block will receive a commision depending on the amount of their BTC account.
This commision is paid by a little transaction fee.
The coin distribution will also be completly different.
All coins will be premined and put in encrypted wallets.
This crypted wallets come with a salted hash of their password and will be publish.
There will be different levels of difficulties.
When someone decrypted a hash he'll be able to send the coins from the mined wallet to his own.
I know that this implicate a high level of trust in the coin creator(s) (You have to trust that he/they destroid all random wallet passwords).
But I concider as an avantage that we don't know how much coins will be mined a day.
This will cut down speculators because if the price increase fast,the production of coins will increase too and the price will stay stable untill all coins were mined.

Please PM if you are interested or answer here.