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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:

SHA256_avx,255,0.0039705,0.0040791,0.00397483
SHA256_basic,175,0.00599706,0.00610304,0.00599851
SHA256_rorx,319,0.00334549,0.00345182,0.00334802
SHA256_rorx_x8ms,319,0.00328481,0.00339317,0.00328667
SHA256_sse4,255,0.00395852,0.00404716,0.00396052

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

https://github.com/laanwj/bitcoin/tree/2016_05_sha256_accel

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, https://github.com/laanwj/bitcoin/commit/431c1b987b34589f32f4c2d0ee0f2571ba70e349

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: https://github.com/bitcoin/bitcoin/pull/7692 or the parallel PR in bitcoin xt, https://github.com/bitcoinxt/bitcoinxt/pull/150
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:

http://crypto.stanford.edu/~dabo/pubs/abstracts/provisions.html

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
https://bitcoinmagazine.com/articles/bitcoin-miners-and-developers-meet-in-california-to-improve-communications-1470158657
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=https://bitcointalk.org/index.php?topic=321228.0]swaps] and [url=https://bitcointalk.org/index.php?topic=321228.0]swaps, confidential
transactions
, 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 ( gmaxwell@blockstream.com 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):


 66cd25ffa2166484f5cca506af1fecb72a1702868baac9f687a6d99a4c320a8f
 4218f7fbd078676cc947f9f65a797152a2264d4ab3b97c7e385988f520141cba
 f0e4bd7e94d13e3dbdf99eb4cbecc2ff06447f9e63b918c59d1507dc8244c5fe
 b21b260817a6bc2431d92f1829c875631df264051a443304542bf1e2d66cb1a3
 5b35bf06f7d662ccc56d8feb52db43d2b4d6f9136d0e13c887dccf237f5a2969
 cacdd00567c30b3e48e49174fb320efbc5aeb270162242a84a205031e68ba382
 cce6b2dd89c42afe1eab3a4dcc560453515cfbd0bf0060c454b0f30340a1598f
 3adcdc564692f00fbb1792e90b8cc3858629b7cca4723a70a704942e447f559d
 b214a090f663c203d07470911089d6f43effbe89dbe5105078e7e9cb7a23f4f8
 463697ba3de7cdf664eec32f733afaafd4420602fac732f7f38a1bd4c042e896
 0a47f478e15c3b380a36c5b814a5c8024f11c502969640f5d941e7dbad6de340
 1cc6fa4c37ac0e74b74b9d5f51aecaa90887bcf94c64258621e01c730ee7fd51
 55192be1a7510c541b02f4db8d4ef5a30339efebf46886ac15526c51d3fbc13d
 12fe77b2b4a698894534c2e77f6d11df205ccf21568e61c16046ebd1ae09b047
 4bf5108b3cced77e9906bd94b87977a8df2438ba2a3a19ba2e1518666c764983
 24390b6848a18bfd30ffbd3e10861515022fea2e30c0cd1ceca777740c7a86ee
 ae53552694144e5a4d840408bd79a62c8746aef4bbc155adf0652c2ea287bdc8
 18d3b40b6638f18e6d1eb5a0b8ca00fcebf64d7604ba5e28af7ff28b49efc977
 7482c567f20dc8672aabe828587e2ce59f6200352b17776503fd13ed3308751f
 58f381eea35ca53be31bd3f5e7080200563660661a2596b1e9ffc272cebeebcb
 c8a6fd916c87ab821815061be9403e10c9c4bac9be36ad7ed912af59abbb4687
 e6ebbd64b839e43d8f7976c13ed07d4fabf004341b0cc13ab2a13f2197ea6bd8
 3729f405cd54916c15988e0921ab309b438728462144ebad61c9f136b10bb58a
 b4afc58224de92107831f47703a4149a801651318f88dbcb8fa9074df3c3162d
 70f1bd6097a4e840f1b0dbdcf263e8cac37fb6105f7b2d0b8fade1f0590d5e5d
 4a9fda6c59b0f17d5438c43fbcfd0023252ff0a86df6e6c20de5ce7bd13983e5
 4a030272358cfb001b376a15e9526225f3714e25b53dbc3f2a13445cdf947ed3
 78239f7808d73021dab9b85ad3abd467b3add4ee03db26d4b6ce1ad1c7abbf60
 f6e5f4e0d4e5727cc5f386c61cdc4c68db4e58db6f7223b2a11fe2e88c8abef2
 47172a10a0718a804c01fff443c5fe6a23f7c763c9a66f5b9971d6bfbdcd0a90
 616ada60080bf656665cb5f32e58fb09d8aa47d156bc29a6bf88ed583990a5c1
 660e09824fe2cf7ca150c085dcbbb2318a3c30b5a0730b5d02eb466b1c7861d7
 6354cf56426648da423c9628fe0826f4e793e9d3a741eda11f106d475ab2d27d
 be5dfe6f2d2fa6b52e824fce271850ab29b1b6898149e33b35e954a0e69a6161
 0dc49684545fb8fa9c791003e70decffec4eab67113b88d7b91bae86600e1f15
 5688d81403121d5609cb39fb62a51d35ee0ecce53a9deb2b4fa62af8fef25926
 2c092e6ba01356699fea40c482c96a519ef1ddc2fbae7da8b04ef724ce9f926e
 fbfd74b5d79ecb35366f4e8d4b8576de7b851ed0758f190a029e6c3fd6ad23fe
 cd926bdc5e2b8c1224b4741466421ea6ae1da0ceb1ace6c7e670d3a31525038a
 97ef4772cc23c39e3cc281dc54474ef49d9f6b93dda3d8d461bb6d07c135bf80
 78450676ae8c2c7e4940ded64a04cf67fbbfc47c912a51c7c8c40a1d5220b769
 32392686c71458c624ca5734244aaf5fe153f92d1a61983ed3717bb1fc329f1b
 1dc72d720c2134632d69f2b6a51f5472634e40f016a68b79425606db42551030
 59732273a5aa07742e85a3add9f1e63d653127df5862e77e89b68f0a9d9c779f
 2bf130de8e1fe22973da372d8b3d21a989d3748aecc9e904699ff05d8f293e31
 881f11442cedfaf3added561eb47f09522b94390e198b5a676b1c7c31c341ba2
 e07d46acec0b936fbfbf4b43f1ada13e1f5bbc9c39319945b35736946fa27c19
 fe2e08e07cdd4b7a9fc70841899af6d59d52b180b4a7d01adf5fe0a1a8a3fdcd
 c2f17bf1c93fb12e3f0e3d54c817f98ad2d68d3e8bb10c1297a92652cebf9f29
 a20f805a45e3c3fbd6e4ea711e68ff2df519490cf7da984c9e4b4740b86ef7fb
 413bd5a599b3f95cee98b0def130fcde7af464fa2122305bf076e60ec523bdc2
 9fdaead9aded7d21dafe5966fa8457ba06eb08b56b863bf2fb507c23c4e37312
 d296caef92e30dbdf52008e2339614ebcd7bceee491a8aac3a46f2bb6a88933e
 fce8acc2d75481901be94d6fd7cfbac4de225e0399556143b49dabbc839e7137
 16b8753d85402e52d154acc07b46d4a416efdba04c9fccaa6e4272446844c1f4
 dcb9aac101988dac9f7b09fc9572830119d241c070d00504f7370e3fd2822e2f
 ab22fba4ffc4dff2820cd01c3e451015b608330d8607327d47aca2eb01125e2a
 88fff8d5fad5e8a3fadee2c4d94b9df3cd8a8dcf3665507c46c32194970f5fbd
 e133b675014146aef7363d492114aec0cc8ee74d800db6d743139a9cb03467cd
 ebd6aebc248dfdfa7af46f19d35f930e643eb3675b6606f1ef5468d84de12315
 533e8c8a49bb39d06226229d3a8e31e67f7fd906a501f192c265d212ae573eff
 8d2b48449687376a464d872a0ca89321535be66691fe504b2ded0774b58548c4
 d237e25e67c78763ec9a68aa3fee055c434155f0d764ca685f37a867ea94a3ea
 007628d3b19d8802946dccebb0eab96935f8c6e11eadd00d9537cb9a9be30491
 faf207a88c6601fc9e637097ee44e775b9610af792b86269dadefdbecab89f89
 f1bfacd6bd3cd18bc55fd6b819843e054b33f6654a87a45c5cefa54349e56b93
 7c25df8d0f98520995b644a17b120679afb6ba083e94ec19667cae09496e6c36
 285f0131b80fadd60e191272e8a2be8760bab8ae2ebf33cdf4721f2938c78760
 700358899649d129dcb45f49474047a6831fea1cb0cb3ccf8eb9593605c9e16d
 cbb261f050dc4a1f248f944acfeac8667db378d4029e3db72c60319af7c516f9
 a06df3f0b737f8ec013d2f64cf4c5bf6b4572f960e0775634ff8b4ecf99d6b49
 42f1905292d8f62d06467a6bbb8a21fb4f354afcb4703520e75cc2c3062a26e1
 ee8a9a7c98af7729efcd419d978ee22ca28f0a1ef28c52fa39f511b1df751eb1
 314daa27edcce90eeda259e14e763bf23832202334ea047031e2c97389608096
 b24efbcc282941055bdc4efe918784045467f2e5b7f7d7f7e0e2fc797a99a0ff
 c8dcfbeaecd894c5c4bb2ea304c0edc33098e123bded906bef500f42d9af12c7
 ad80e0452a88dfdeac137d7d8bb5176a215709bd3f833815ad66ffc3efc02361
 eaf23f317ba9db8f00a3e971c3d58707a756a5dc7a31f0d41dd7ddac01bf55f4
 c1d3592866cabb91d06ab8f285aded45d6d9131b34fc0eb131e7f21c66c1a34d
 bfe36e4d6af62571a26596a0671c3701997c4b612bf9ffda4c48ca8ffca92a20
 37025dfe5cd66c3ddd30a334d31e4f32618bd68b187e60e5872ed769246fad43
 077619db4bbda76b0dbae8f78f365ac0d605d8f83ce70641669226d4f1ba5bb2
 053667aadffee3a96782e025af297bf832402879e1f3767e73fd98f128b40e65
 ca065d660b2fd47cdd82d650cb30cca1e29aafb45f67c32e6c3e66d00c935270

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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