Dub 14

Core Dev Maxwell: UASF ‘Does Not Measure Up To Standard’

· April 14, 2017 · 9:00 am

Bitcoin core developer Greg Maxwell has newly outlined why he “does not support” a user-activated soft fork (UASF) as it figures in BIP 148.

Maxwell: UASF ‘Guarantees Disruption’

In a circular to the Core mailing list Friday, Maxwell said that although he is not strictly against a soft fork, its incarnation in BIP 148’s UASF does not “really measure up to the standard set by segwit itself.”

The debate over whether to galvanize the entire Bitcoin ecosystem into Segwit activation via a UASF has gained considerable traction over the last month.

Proponents say it is the quickest way to move Bitcoin on from its current stalemate, yet detractors highlight its disruptive nature as a reason for caution. If a UASF occurred, for example, non-supportive miners would find their blocks invalid after the deadline, and would not receive rewards for their work.

Maxwell too notes that this “disruption” is a key difference between a UASF and segwit activation via miners.

“The primary flaw in BIP148 is that by forcing the activation of the existing (non-UASF segwit) nodes it almost guarantees at a minor level of disruption,” he continued. “Segwit was carefully engineered so that older unmodified miners could continue operating _completely_ [sic] without interruption after segwit activates.”

Time Still Not Of The Essence

Despite the increasingly slow and expensive nature of the Bitcoin network, Maxwell still advocates a measured approach without speed as a priority.

…The fastest support should not be our goal, as a community– there is always some reckless altcoin or centralized system that can support something faster than we can– trying to match that would only erode our distinguishing value in being well engineered and stable.

First do no harm.’ We should use the least disruptive mechanisms available, and the BIP148 proposal does not meet that test.

The developer has meanwhile found himself under fire lately from Bitcoin Unlimited proponents, notably Roger Ver, who released a dedicated presentation with quotes from Maxwell highlighting alleged errors.

“It’s important the users not be at the mercy of any one part of the ecosystem to the extent that we can avoid it– be it developers, exchanges, chat forums, or mining hardware makers,” Maxwell concluded.

Ultimately the rules of Bitcoin work because they’re enforced by the users collectively– that is what makes Bitcoin Bitcoin, it’s what makes it something people can count on: the rules aren’t easy to just change.

Meanwhile, Bitcoin’s recent price spike over $1,200 has been attributed by some to a sharp rise in the number of UASF-signaling nodes. Though this does not necessarily imply causation, the price has also dipped following the publication of Maxwell’s post.

What do you think about Greg Maxwell’s perspective on a UASF? Let us know in the comments below!

Images courtesy of uasf.org, twitter.com, shutterstock

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Dub 06

ASICBOOST: Bitmain to Respond ‘Soon’ to Exploit Accusations

· April 6, 2017 · 5:00 am

Bitmain CEO Jihan Wu has vowed to respond ‘soon’ to accusations the miner is exploiting a Bitcoin vulnerability to manipulate mining.

Bitmain, Vulnerability Outing ‘Huge SegWit Confidence Boost’

A “covert” use of so-called ASICBOOST technology was circulated to the Core mailing list by contributor Greg Maxwell Wednesday. This would allow “a major manufacturer” to unfairly profit from centralization.

While Bitmain was not named by Maxwell, community sources subsequently confirmed the company’s involvement.

Maxwell wrote:

Exploitation of this vulnerability could result in payoff of as much as $100 million USD per year at the time this was written (Assuming at 50% hash-power miner was gaining a 30% power advantage and that mining was otherwise at profit equilibrium).  This could have a phenomenal centralizing effect by pushing mining out of profitability for all other participants, and the income from secretly using this optimization could be abused to significantly distort the Bitcoin ecosystem in order to preserve the advantage.

The Core developer also proposed solutions to prevent the attack becoming a major problem, in a move praised by Tone Vays as “a huge confidence boost” for the SegWit supporters.

Wu: Bitmain Statement ‘Soon’

Wu meanwhile stated Bitmain would provide a statement “soon.”

Previously, suspicion had already fallen on the Bitcoin Unlimited supporter, with community members noting he had deleted tweets about ASICBOOST. They added Wu’s BU support could be linked to the Bitmain operation.

While ASICBOOST was originally invented by Sergio Lerner among others, who also contributes to SegWit concepts, Maxwell stated that none of the technology’s creators were “aware” of the exploit.

“Reverse engineering of a mining ASIC from a major [manufacturer] has revealed that it contains an undocumented, undisclosed ability to make use of this attack. (The parties claiming to hold a patent on this technique were completely unaware of this use.),” he continued.

On the above basis the potential for covert exploitation of this vulnerability and the resulting inequality in the mining process and interference with useful improvements presents a clear and present danger to the Bitcoin system which requires a response.

In Summer 2016, KnCMiner declared bankruptcy over the Bitcoin block reward halving causing them unsustainable overheads.

The firm had previously been taken to court in its native Sweden by customers complaining over delays and defects with its products.

The startup had meanwhile raised over $32 million in investment.

What do you think about Greg Maxwell’s post? Let us know in the comments below!

Images courtesy of Twitter, Shutterstock

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Úno 13

The Scoop on JoinMarket and Confidential Transactions

Source: bitcoin


Today we’ll be taking a gander at JoinMarket and Confidential Transactions. I’ve known of these technologies for a while but have not used them nor do I plan to until the volume of utilization increases. As it stands, I don’t find a pressing need for obfuscating transaction history further than it already goes with BTC. I already generate new addresses each time I request payments. I can’t see why anyone other than a money launderer would desire a form of mixing service or transact. Now I know we can potentially bring pseudo-anonymity to perhaps full anonymity. Not to copy Jeff Goldblum, ‘We knew we could, but did we stop to think if we should?’ should be considered here.

Also Read: Solving Blocksize With a two-pronged Proposal


I found out about Joinmarket (JM) a few weeks ago when lurking on the #bitcoin IRC chat room and overheard Belcher mentioning that he coauthored it. JM is a marketplace that utilizes Coinjoin transactions. Coinjoin is a means of anonymizing transactions by allowing different users to make joint payments to a given output address, thus obfuscating the origin sender. Join market is a command line tool designed to pool resources together in common to allow them to act as a peer to peer mixer, giving bitcoin holders a method to earn small fees from mixing in the process. Join market is live and in action using GitHub as a repo source. it appears to be a few python scripts and to connect potential markets via Tor-connected IRC chatrooms. Their IRC room revealed an order book. At the time I checked there are 178 market orders possible by 53 different counter parties.
The way it works is you can post your wallet and depth levels into the joinmarket for a fee of your choosing. In the picture, we see someone generous and freely offered BTC mixing in JM for just under 130 BTC. That means you could mix up to 130 BTC in a transaction and have it not linked to your addresses explicitly. It appears that the market is there for peer mixing if you’re interested. To acquire the client you simply git pull the repo using a command line terminal on your os (If using windows you should download a gitbash interpreter.)

Confidential Transactions

Confidential transactions (CT) is an entire system and concept, proposed by Greg Maxwell. Also known as Confidential Values, CT removes the amount 8-Byte amount field in bitcoin and instead implies the values instead through additively homomorphic commitments, using the commutative property of addition.

The added benefit of removing the amount field data would be the addition of a memo data contained instead — a feature that could enable the storage of invoice data or even a refund address — potentially. (Imagine a world where bitcoin payments possibilities to enable real-time shopping with a QR code scanner… and you had 2048 characters to indicate address phone number message and shipping speed all from an app using the tv and a phone).

However, all is not yet clear with CT. For with the concept alone using Petersen based commitments, it is very easy to overflow data – overflowing data out of range will cause the value to go negative. Though to further complicate matters, it appears that the way to solve this overflow issue is with an assertion of a boolean based container system, specifically combining Petersen commits with ring signatures. Using this method, we break down the private key into a corresponding 33-bit key container-space that would either resolve as a 0 (valid and spendable) or a not using the inferred reference methodology explained above.

The final closing of Maxwell’s paper suggests that Confidential Values work implemented in tandem with Segregated Witness and can potentially solve issues with tracking amounts in the Coinjoin and mainly join market’s implementation. There was even recent discussion of how CT could implement via a soft-forking change, on the Bitcoin Mailing List. It will be very interesting to see if either of these efforts gain more traction throughout the year through usage or discussion amongst the community, though they take time and review. I’m going to start the rumor that if we can’t soft-fork implement CT into main-net BTC, then it’s going into Blockstream Elements.

What are your thoughts? Would you use JoinMarket as a service, why are why not? Do you consider CT to be too crazy difficult and/or unnecessary to implement? Why or why not?

Photo Credits: Frankenmint

The post The Scoop on JoinMarket and Confidential Transactions appeared first on Bitcoinist.net.

The Scoop on JoinMarket and Confidential Transactions