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August 25, 2016, 02:45:45 AM *
News: When 0.13.0 is released in the near future, make sure that you carefully verify it.
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1  Bitcoin / Development & Technical Discussion / Re: Bitcoin profiling results on: August 23, 2016, 12:53:16 AM
Why isn't that done yet?  Because until very recently it was burred in the profiles; optimization elsewhere has exposed it.

Any such change has to be done with great care because of consensus consistency of course--

and optimized hash functions for non-parallel use are not ~THAT~ much faster:


basic is the plain code we have today, the fastest in that test (rorx_x8ms) is only 1.825x faster.

I expect this to go into 0.14 sometime relatively soon.

Use of a 4-way implementation would speed it up further, but making good use of 4-way sha2 is technically somewhat difficult-- not just a drop in change, and there are only a few places where it can really be used at all.

Wladimir has done similar testing for the CRC32c,

in all cases, these higher performance versions require use of special instruction sets that aren't available on all systems so additional code is needed for runtime autodetection. Not a big deal, but part of the reason that it wasn't magically changed the moment it was the highest point in the profile.

2  Bitcoin / Development & Technical Discussion / Re: Turing completeness and state for smart contract on: August 20, 2016, 01:03:41 AM
The gist of an earlier comment of yours seemed to be: "writing smart contracts is inherently hard and unnatural, so it's fine if the scripting language is hard to understand." I just don't see how one aspect of writing contracts being hard (getting the logic right) implies that it would be better for other aspects to be harder than they need to be.

If a declarative version of Bitcoin script made mistakes less likely, what is the downside? Are you worried about newbs who just learned a bit of javascript thinking they can write secure smart contracts just because Bitcoin script v2 might look a bit more like javascript? So the fact that current script looks intimidating is actually good? If so would it have been even better if Satoshi made all op codes of the form OP_XYZ where X, Y, and Z were digits? And maybe disallowed spaces when not including them would still be unambiguous? That would certainly reinforce in people's mind that writing Bitcoin script is tricky.

You misunderstood what I was saying.

A declarative model doesn't reflect the reality of these systems well. It is easier to get started, but hard to do things right, and very hard or impossible to to be confident that you got things right when you did.

A more functional model reflects the reality of the systems better, while also providing powerful scaling and analysis benefits.  I believe it is possible to construct systems which are harder to get started, but once you get something working its very likely to get things right, and hard but far from impossible to _prove_ you're achieving the properties that you set out to achieve.

I haven't proven that better can be done, yet (unless you count Bitcoin script)-- but what DAO/ETH seem to be proving is that at least that design is too dangerous to be used-- when their highest profile contract, reviewed by the designers of the system/language, got robbed blind by a rather simple vulnerability.
3  Bitcoin / Development & Technical Discussion / Re: Questions about hash_serialized, returned by gettxoutsetinfo on: August 17, 2016, 09:15:46 AM
The only purpose of it is bitcoin core specific software testing, it's effectively free to compute while returning those other statistics, and it allows rapid isolation of suspected database corruption or inconsistency.

The structure of the hashing is not well suited to other applications.

and xor all the hashes together to get the final value.
Congrats, you win today's failed cryptography trophy. Smiley That kind of structure is trivially to second preimage attacks using wagners algorithm for solutions to the subset sum problem.  Order independent accumulators are a tricky subject, the only that I'm aware of that have any real argument for security have huge hashes and are very slow.

The data hashed here is also _highly_ implementation specific and subject to change in any new version without warning.
4  Alternate cryptocurrencies / Altcoin Discussion / Re: [ANNOUNCE] Ixcoin - a new Bitcoin fork on: August 17, 2016, 02:11:12 AM
Your project contains the old centralized "alert" system previously copied from upstream Bitcoin. This system lets the holders of a private key send messages to be displayed in the error field. Because of its limited utility, potential for abuse, known disclosure of the key to at least one untrustworthy party (and is believed to be compromised), and frequent use to justify other centralizing features this system has long been deactivated (and now is completely removed) upstream.

I would recommend you remove this system by adopting this code from upstream: or the parallel PR in bitcoin xt,
5  Bitcoin / Development & Technical Discussion / Re: Using the confidential transaction sum for proof of reserves on: August 11, 2016, 10:18:21 AM
CT for solvency proofs is well known, I posted about it here (someplace) on the liabilities side some time ago.

Whats even more interesting is that private assets side is also possible in Bitcoin today:

Unfortunately there is relatively little interest from most exchanges in these tools.
6  Bitcoin / Development & Technical Discussion / Re: why are people trying to hide their IP? on: August 10, 2016, 10:05:16 PM
There are several companies performing sybil attacks on the network.  They connect to every node they can reach (the 8 limit is for _outbound_ connections) and also listening to connections, running many fake nodes so that it is likely that you will connect to them. They also monitor the timing of addr messages to attempt to infer which addresses are connected to the nodes they are connected to.

By monitoring the timing of transaction announcements they can learn a lot about transaction origins, especially if addresses are reused.

As far as i understand, it's even a bad idear to use bitcoin and tor:
This is highly misleading. The claim is that attackers can DOS attack tor exits, causing a tor using Bitcoin user to potentially need to stop using Tor during a DOS attack.

This is untrue because normally with tor Bitcoin nodes are connecting to other bitcoin nodes as hidden services, no exit is involved... and not very relevant because, "maybe tor gets DOS attacked and you need to either wait or switch it off" is in no way worse than never using tor in the first place.
7  Alternate cryptocurrencies / Altcoin Discussion / Re: Is the blockchain's purpose being redefined by the forked Ethereum Community? on: August 04, 2016, 08:07:13 PM
It didn't start with them. It started with people pushing for a hardfork in Bitcoin making the factually unsupported claim that whatever "the most" hashpower says is what happens.

The fact that Bitcoin software has _never_ worked like that (nor any altcoin that I'm aware of) hasn't phased them. Ethereum has just been running what that misunderstanding. It'll be pretty interesting to see what happens when ETC ends up with more hashpower.
8  Economy / Games and rounds / Re: 1000 BTC GIVEAWAY! From your friend rekcahxfb on: August 03, 2016, 04:48:47 PM
Hey, rekcahxfb.

You should post a list of eligible addresses once your contest closes.

Then you should use a block that comes after to randomly and uniformly select the winner.

(For those who didn't notice, the coins here appear to be unrelated to bitfinex at least)
9  Bitcoin / Bitcoin Discussion / Re: Another closed door Core - Chinese miners meeting on: August 02, 2016, 06:08:53 PM
10  Bitcoin / Bitcoin Discussion / Re: Another closed door Core - Chinese miners meeting on: August 02, 2016, 08:07:47 AM
They came out to meet with many parties in the area, in fact. You just hear about it in this case.  The meeting was mostly social-- discussing our common passion (Bitcoin) and trying to improve communication.   I think notes are going to be posted, in fact, because we're dweebs like that.

I thought it was really positive-- and good to meet up with people face to face that I'd only talked with in email before.

The Bitcoin industry seriously needs better communication-- especially crossing language and cultural barriers-- rather than hot comments on social media. Improved communication will lead to fewer potential avenues for miscommunication and better cooperation in the future.  Don't buy into rbtc fud. Smiley
11  Bitcoin / Bitcoin Discussion / How have fungiblity problems affected you in Bitcoin? on: July 29, 2016, 02:33:27 AM
Privacy and fungiblity are essential components for any money-like system.
Without them, your transactions leak information about your private
activities and leave you at risk of discriminatory treatment. Without them your security is reduced due to selective targeting and your commercial negotiations can be undermined.

They're important and were consideration's in Bitcoin's design since day one. But Bitcoin's initial approach to preserving privacy and fungiblity -- pseudonymous addresses-- is limited, and full exploitation of it requires less convenient usage patterns that have fallen out of favor.

There are many technologies people have been working on to improve fungiblity and privacy in different ways-- coinjoins[url=http://and [url=]swaps] and [url=]swaps, confidential
, encrypted/committed transactions, schnorr
multisignature, MAST, better wallet input selection logic, private wallet scanning, tools for address reuse avoidance, P2P encryption], ECDH-derived addresses, P2P surveillance resistance, to name a few.

Having some more in-the-field examples will help prioritize these efforts. So I'm asking here for more examples of where privacy and fungiblity loss have hurt Bitcoin users or just discouraged Bitcoin use-- and, if known, the specifics about how those situations came about.

Please feel free to provide links to other people's examples too, and also feel free to contact me privately ( GPG: 0xAC859362B0413BFA ).

I also posted this question on Reddit, but though I might get a broader audience here.
12  Economy / Exchanges / Re: Coinbase now supports Etherium; Is this a threat to Bitcoin dominance on: July 25, 2016, 11:52:20 PM
Heavily pre-mined (80%-ish currently), endlessly inflationary, 'cryptocurrency' which doesn't even provide ledger immutability...

13  Bitcoin / Development & Technical Discussion / Re: Incentivizing Bitcoin Nodes on: July 25, 2016, 11:07:40 PM

"Nodes with open ports are able to upload blocks to new full nodes. In all other ways they are the same as nodes with closed ports."

The contributor of those two lines makes it sound as if this difference between the two is negligible, when it isn't.

In fact, that quoted text sounds like it's overstating the differences-- nodes without open ports still forward blocks too.  The difference is that they make outbound connections and so they can't connect to each other... and now that HS support is integrated, even that difference is diminishing.
14  Alternate cryptocurrencies / Altcoin Discussion / Re: Bitcoin based Blockchain compression algorithm on: July 24, 2016, 07:19:22 PM
0.8.6 is what most altcoins are based on, it is an old codebase with many vulnerabilities. Also look at the screenshots. This is in the wrong subforum.
15  Bitcoin / Bitcoin Discussion / Re: Release - Open source software - replacing hardware wallets with image { on: July 23, 2016, 08:39:42 PM
This kind of steganography-- hiding data in the least significant bits of images-- is _very_ easily detected by statistical methods, and there are many papers and tools (stegdetect, for jpeg as an example) to do so.

At a minimum, something hoping to perform successful image steg embedding should be using wet paper codes.

16  Bitcoin / Development & Technical Discussion / High-S transactions, help finding origins? on: July 20, 2016, 10:40:18 PM
There is still a steady flow of high-s transactions hitting the network. The only reason they get mined now is because of some people running special nodes that mutate them to make them acceptable.

Is anyone interested in trying to find the sources?

Here is a list of txids for transactions which appear to have originally been high-S (these are the IDs for the mutated forms that had a chance to get confirmed):


17  Economy / Exchanges / Re: Coinbase Patents on: July 20, 2016, 06:33:49 AM
To my understanding a pledge such as the one by Blockstream is legally binding.
Correct. And in addition to the pledge we have the DPL and MIPA which are two additional distinctive ways that users get protective coverage. These provide additional assurance in case of any limitation or issue with the pledge (and vice versa).  (MIPA is kind of narrow: it says the inventors are also able to grant licenses for defensive use)
18  Bitcoin / Bitcoin Discussion / Re: Mark Karpeles on bail on: July 15, 2016, 01:28:00 AM
Hold your pitchforks on that point.

In the US at least, most people don't usually pay their own bail. You use a bail bondsman who loans you money for the bail and, presumably, comes and breaks your kneecaps if you don't make payments on the loan or skip down on your bail. They'll sometimes take the title on some property of yours to secure the loan.

I assume the situation is no different in Japan.
19  Bitcoin / Bitcoin Discussion / Re: Who really owns and manages Bitcoin? on: July 14, 2016, 05:13:52 PM
You can clearly see who can approve new code in GitHub here.
No, you can't-- that is listing org members (and not even all of them since some have set themselves to private-- in fact, when you linked to it I noticed I was set to private and just fixed that, there are 22). It's the list of people who can be assigned to trouble tickets.

There is no set of people who can "approve code", except all the users of Bitcoin-- there are no automatic updates for a reason.
20  Bitcoin / Bitcoin Discussion / Re: Bitcoin and me (Hal Finney) on: July 14, 2016, 12:14:45 AM
If what some people on this page of the topic have written is true, and the mind / soul does not disassociate from the body at death, then it could be that Hal's soul is currently locked up in his frozen brain and body, saying "FORGET IT!!!  THIS WAS A BAD IDEA!!! THIS WASN'T SUPPOSED TO WORK LIKE THIS!!! LET ME OUT!!! KILL ME KILL ME KILL ME KILL ME KILL ME..........."

I don't think anyone here wants to do him like that, do we?
You can imagine things like that but it's oddly specific. Why that yet not have that be the problem when people are burried rather than cremated (or vice versa).
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