Topic: Interesting non-altcoin forks? (Read 4097 times)

BTW, isn't there a fork that does blockchain pruning already?

Something that I've wished for in Bitcoin core itself the last few days is an option to monitor the size ( in both transactions and kilobytes) of the memory pool of unconfirmed transactions.  I've been seeing it get up to 3000 or so and staying there for hours during the last few days, while some miners continue to turn in tiny 60k blocks that have a few dozen transactions at most.  

Bitcoin XT is a patch set on top of Bitcoin Core, with a focus on upgrades to the peer to peer protocol. By running it you can opt in to providing the Bitcoin network with additional services beyond what Bitcoin Core nodes provide. Currently it contains two additional features:

• Relaying of double spends. Bitcoin Core will simply drop unconfirmed transactions that double spend other unconfirmed transactions, forcing merchants who want to know about them to connect to thousands of nodes in the hope of spotting them. This is unreliable, wastes resources and isn't feasible on mobile devices. Bitcoin XT will relay the first observed double spend of a transaction. Additionally, it will highlight it in red in the user interface. Other wallets also have the opportunity to use the new information to alert the user that there is a fraud attempt against them.
• Support for querying the UTXO set given an outpoint. This is useful for apps that use partial transactions, such as the Lighthouse crowdfunding app. The feature allows a client to check that a partial SIGHASH_ANYONECANPAY transaction is correctly signed and by querying multiple nodes, build up some confidence that the output is not already spent.

Bitcoin XT is more experimental than Bitcoin Core, and has a strong emphasis on supporting the needs of app developers and merchants. By running it you not only provide additional services to the network but help build confidence in the implementations, contributing towards consensus for inclusion in a future version of Bitcoin Core.

I believe that is incorrect. The only non-trivial contributions that I can think of there is jtimon (freicoin).

If Satoshi had agreed with that point of view, it seems unlikely he would have released Bitcoin under the MIT License. 'Course it's hard to disagree with your sentiment regarding the quality of most altcoins....

Nothing special is when they rename it, use a source which they are not made and then add some salt in it.

Regarding my original question: I mostly wanted to know about interesting extensions to the original code (and no, not altcoins).

Making something new from the bottom is the real thing and I support only that.
The original idea, not stolen one.

Many contributors have own coins.

use a source which they are not made

Making something new from the bottom is the real thing and I support only that.

For me, the most important one is the UTXO commitments proposal but I have no idea what its status is.

Interesting, and also quite controversial

A (slightly related) interesting fork: Tom Harding's Double-Spend Relay and Alerts. It actually made it into Bitcoin Core's master for a short while before being reverted (which I think is a shame; he put a lot of work into it and it had at least some chance of being very useful, but there were some legitimate concerns as well).

I use mostly python; does anyone has experience with BitcoinJ's python bindings?

Regarding my original question: I mostly wanted to know about interesting extensions to the original code (and no, not altcoins). For example, I only recently learned about this PR to prune bitcoin core's wallet: https://github.com/bitcoin/bitcoin/pull/5389

Which caused me to wonder what other interesting PR's are out there...

Interesting tree: Peter Todd's replace-by-fee fork.

Double-Spend Relay and Alerts

---

VERY IMPORTANT: It has never been safe, and remains unsafe, to rely
on unconfirmed transactions.

Relay
When an attempt is seen on the network to spend the same unspent funds
more than once, it is no longer ignored.  Instead, it is broadcast, to
serve as an alert.  This broadcast is subject to protections against
denial-of-service attacks.

Wallets and other bitcoin services should alert their users to
double-spends that affect them.  Merchants and other users may have
enough time to withhold goods or services when payment becomes
uncertain, until confirmation.

Bitcoin Core Wallet Alerts
The Bitcoin Core wallet now makes respend attempts visible in several
ways.

If you are online, and a respend affecting one of your wallet
transactions is seen, a notification is immediately issued to the
command registered with `-respendnotify=`.  Additionally, if
using the GUI:
 - An alert box is immediately displayed.
 - The affected wallet transaction is highlighted in red until it is
   confirmed (and it may never be confirmed).

A `respendsobserved` array is added to `gettransaction`, `listtransactions`,
and `listsinceblock` RPC results.

Warning
If you rely on an unconfirmed transaction, these changes do VERY
LITTLE to protect you from a malicious double-spend, because:

 - You may learn about the respend too late to avoid doing whatever
   you were being paid for.
 - Using other relay rules, a double-spender can craft the double-
   spend to resist broadcast.
 - Miners can choose which conflicting spend to confirm, and some
   miners may not confirm the first acceptable spend they see.

What's replace-by-fee?
----------------------

Currently most Bitcoin nodes accept the first transaction they see
spending an output to the mempool; all later transactions are rejected.
Replace-by-fee changes this behavior to accept the transaction paying
the highest fee, both absolutely, and in terms of fee-per-KB. Replaced
children are also considered - a chain of transactions is only replaced
if the replacement has a higher fee than the sum of all replaced
transactions.

Doing this aligns standard node behavior with miner incentives: earn the
most amount of money per block. It also makes for a more efficient
transaction fee marketplace, as transactions that are "stuck" due to bad
fee estimates can be "unstuck" by double-spending them with higher
paying versions of themselves. With scorched-earth techniques⁵ it gives
a path to making zeroconf transactions economically secure by relying on
economic incentives, rather than "honesty" and alturism, in the same way
Bitcoin mining itself relies on incentives rather than "honesty" and
alturism.

Finally for miners adopting replace-by-fee avoids the development of an
ecosystem that relies heavily on large miners punishing smaller ones for
misbehavior, as seen in Harding's proposal⁶ that miners collectively 51%
attack miners who include doublespends in their blocks - an unavoidable
consequence of imperfect p2p networking in a decentralized system - or
even Hearn's proposal⁷ that a majority of miners be able to vote to
confiscate the earnings of the minority and redistribute them at will.

I use BitcoinJ quite a bit. I like it. It's very powerful and convenient.

I agree with this. Java Bitcoin library indeed.
It is compatible with Python, Ruby and Clojure running on a JVM.
People work on this hard to make something good. And it is good, but the question is the usage of it.