Post
Topic
Board Altcoin Discussion
Re: Decentralized Timestamp
by
gmaxwell
on 16/05/2014, 17:01:37 UTC
nope, can be done.  I have a working model.  see:  http://www.stanford.edu/class/cs240/readings/lamport.pdf
I'm familiar with that paper and have linked to it on the forum before. Note that Lamport is talking about a distributed system, not a decenteralized one.  As I recall process he describes is not byzantine robust, requires a jamming proof broadcast network, and does not have anonymous membership (the players must be selected in advance, so it cannot meet our definitions of decenteralized— in particular it needs a consensus arbitrary ordering of player identities to break ties).

As far as POS goes, I've not seen anyone tender a solution to the nothing at stake problem, and so I still consider it non-viable for a decentralized consensus. PPC makes it work by requiring POW and using centralized block signatures. NXT was previously making it 'work' by not releasing the complete source to their software, I haven't checked lately.  So far POS schemes all suffer from attacks like former quorums (e.g. people who held coins at some point in the past) can costlessly replace the history by forking off from a point where they did have a quorum after they no longer do, and from things like the optimal income producing mining strategy is to mine all forks (because there is ~0 marginal cost in mining a fork) instead of a single one. Schemes like honesty bonds do not help a node decide between two different networks— the real one and a simulated one, and cannot punish someone if they perform the attack after exiting the network completely.