Questions about bitcoin/other stuff.

[A_Free_Man]

Well I'm an amateur programmer with a lot of interest in the workings of bitcoin and thought I'd try my hand at making my own(Not using the bitcoin source like the rest, just taking some of the concepts). So I have questions about how bitcoin(and the other CCs) work/s that you guys can probably answer easier then hours reading the source can.



Here are thee questions.

1. How can a change be made in the bitcoin hashing method now that it is so widespread, does it require 51% control or would there be a way around this?

 
2. To prevent deflation my currency would have no vertical limit(hold off on those hyper-inflation posts), each block generates 8 units which can be further divided into coins(128 each). Would using the clients to passively scan the blockchain for addresses that haven't been used for a long time(year) be a good way to go about this? Or to somehow have the burden placed upon the miners? (Dead_Coins would decrease the difficulty by the percentage of dead coins in relation to the total coins)


3. Is there anyway to use miners as a way of cleaning the block history of transactions that are no longer of importance(would only be after the coins new owner is already known in recent the recent block history).


4. Would adding a public/private key system for a new field in the blocks for each coin be too taxing on the hard-drives of users? (This is my idea on a colored coin system, an address gets a private and public key associated with the creation of a Unique_ID that would be broadcast in the block-chain similar to transactions.)


5. Concerning question 2; is there anyway to prevent a 51% attack(with the aim of considering all coins dead). Or to prevent a 51% attack in general.




Less-Bitcoin related but some of you are probably the most qualified to answer-

1. What hashing would be best to resist quantum computing's super-solving abilities, also with a low-collision probablity?

2. Which of the public/private key systems are the most secure?

[lbr]

51% attack is non-profitable for attacker => probability is low

[A_Free_Man]

51% attack is non-profitable for attacker => probability is low

It is profitable, dead coins still exist and if that address ever becomes active again they will no longer be considered dead. But the amount of dead coins there are contributes to a function that will lower the difficulty by a small percentage(once a threshold is reached).

Edit:
-Or do you mean the decrease in value of the currency would make the attack pointless?

[lbr]

51% attack is non-profitable for attacker => probability is low

It is profitable, dead coins still exist and if that address ever becomes active again they will no longer be considered dead. But the amount of dead coins there are contributes to a function that will lower the difficulty by a small percentage(once a threshold is reached).

Edit:
-Or do you mean the decrease in value of the currency would make the attack pointless?

Yes.

Basically if you will create a device which will be hashing at >=51% of of overall BTC hashrate it is much more profitable to just mine new blocks or receive transaction fees. Assuming that you actually pay for your hardware.
Ofc if attacker is just very very rich and wants just to destroy BTC.. then attack is not pointless ; )

[A_Free_Man]

Bump before I go to sleep.

[A_Free_Man]

Well this is disheartening no more answers. Well guess I'm off to study the source.