Quote from: jonald_fyookball on April 26, 2014, 12:33:21 AM

Thanks clout. Very good topic and
thanks for providing the links so
we can compare the 3 systems.

Here's just my 2 cents on the
matter:

I think the most important things
are how are new blocks formed,
and how is consensus achieved.
(Minting is a distant second,
and I didn't delve into that).

I'll give my summary of each
system and my conclusions to follow.

1. Peercoin:

- Instead of using the longest
chain method, they use the
chain with the longest "coin days"
of the transactions in the blocks
in the chain.

An interesting proposal, seems to work
in theory because someone
with a large wallet who sends
themselves coins goes back to
0 coin days, and thus cannot
be easily manipulated.

However, in practice is currently
relying on checkpointing... and
the whitepaper admits it
may not even work as well
as Bitcoin to prevent a 51%
attack.

2. Nxt

This uses a semi-random
deterministic protocol to
decide what node forges
the next block.

While this sounds quite neutral
and fair, the downside is this:

Quote

Up to 720 recent blocks can be "re-organized" by the network in case of problems,
so a transaction is considered irreversible after 721 confirmations. Transactions that have been confirmed 1440 times are considered permanent

.

with 60-second blocks, 1440 minutes = 24 hours to fully confirm. Not great.
If this could be improved, it would be excellent.

3. Bitshares:

Uses a "delegated proof of stake" protocol,
which is similar to the Ripple consensus algorithm
(basically a club of trusted nodes) except you
use your shares in the coin to vote for what
nodes you trust ("delegation").

The positive side of this system is faster
confirmation, but its more centralized.

They make the point that Bitcoin isn't really
that distributed due to mining pools, and
other proof of stake systems aren't really
that distributed due to people not running
full nodes...

Conclusion:

(these are just my initial OPINIONS,
which always subject to revision):

Bronze Medal: Bitshares.

I like the Bitshares solution the least out
of all 3. It seems far too centralized
and dependent on people rather than math,
although it still seems like it could work.

Silver Medal: Nxt

Currently, it takes way too long to fully
confirm transactions, but has some powerful
principles behind it, very well documented,
with smart people...and probably further
research could be done to improve confirmation
time.

Gold Medal: Peercoin

I like this solution the most because
it is the simplest. Simple solutions
are usually the best, which is why
proof-of-work and longest chain has
stood the test of time.

It would be nice to see if Peercoin
would work without checkpointing.

-----

There you go. Will be interesting
to see what other folks think.

interesting and educational post.