We all know QCs are being worked on but most likely decades away from being a danger to ECDSA used in Bitcoin... that said though, when that day does arrive, either due to QC or some mathmatical genius figures out how to break it, it seems prudent to have another signature system in the wings that people could opt to move their coins to.

I'd like to discuss the pros/cons of implementing lattice signatures in bitcoin now such that when ECDSA is broken it's an orderly transition to use a different lock on funds.

I'd also like to suggest that we add an optional PoW on a transaction submitted to a node so that when someone submits their transaction they can provide a PoW of that Tx alongside to the node to show they really want the tx to be included.

In normal usage like we are today, no PoW for a Tx is required.  But if there is a systemic compromise of existing transactions, this PoW feature could be enabled by miners such that they only repeat a tx with PoW offered along side it.  This way even if the unlikely event of a large QC being made and used to attack the network happens, there is a plan on how people can safely move their bitcoin to an alternative locking mechanism.

Thoughts?

If I have an xpub key (well ypub, but same thing) from my Trezor and I want to query this coldstorage balance using bitcoind... I can't see an obvious way to do this and feel I must be missing a trick as surely everyone does this?

In absence of bitcoind allowing an xpub key query directly, I believe we can generate a bunch of addresses from the xpub key and was planning on asking bitcoind via rpc calls the balances of these addresses however this doesn't seem straight forward.  Firstly it requires rescanning which seems like it would be unworkably slow as addresses are generated all the time.  Secondly it would indicate another bitcoin node (or at least another bitcoin wallet) would need to be created since it would conflict with my hotwallet.

I see many sites do offer exactly this capability so looking for help on how to do this.

I don't want to use any external API service like blockchain.info or trezor.io since I want to actually do this using our own tech stack.

Any help/pointers really appreciated. 

(We use node.js as a backend if anyone happens to know any node modules that may help too.)

Thanks,

Would like some help on a weird question...

I have an old transaction I generated about 2 years ago on an offline computer however I never published it.  The intention was that I'd keep this transaction and post it in future when I want to access the paper wallet funds.

It was to transfer 0.1 BTC from my paper wallet to my hardware wallet address.

I've not spent the paper wallet and my hardware wallet is still the same, is there any risk in publishing this old transaction? 

Is there a date/timestamp in there that may cause miners to reject it and/or cause it to linger in the mempool meaning I can't spend it for some reason if this fails?

I'm looking for a self contained JS module that will take a key in hex string form such as

Code:

var k = create_private_key_hex_string(); // Gives hex string of "a01045825b3459874345987234";

and allow creating a public key via EC to give

Code:

var pubkey = derive_public_key_hex_string( k ); // gives { x : "deadbeef983457903845", y:"ab348989745609456" }

and create a signature via ECDSA such that I can do...

Code:

var msg = "hello world"
var msg_hash = create_sha256_hex_string( msg ) // gives hex string "b309234654234986094609486.."
var signature = sign_hash( msg_hash, k );  // gives another hex string "54907567b309234986094609486.."

and finally allow verify

Code:

var is_valid = verify( signature, msg_hash, pubkey );

Basically a really easy JS module that has these simple methods all taking hex strings as input

•   create_private_key_hex_string();
  
•   derive_public_key_hex_string( k );
  
•   create_sha256_hex_string( message );
  
•   sign_hash( msg_hash, k );
  
•   verify_hash( signature, msg_hash, pubkey );

Ideally so it works in all browsers and in node.js.


Any suggestions or anyone willing to make it?  

It just needs to work easily in all browsers and in node.js and not require babel or dependencies.

[Basically we want to make it super easy for game developers and game players to use bitcoin.]

Hi all,

I've been a Bitcoin advocate for quite some years now and even with the plethora of exciting other coins I still see bitcoin as the leading candidate for value representation on the internet.  I'd like to share a glimpse into the project I'm involved in as a few others here may find the project of interest.  We are working to build a system to bring Bitcoin payments to the mainstream video game world.

What we are doing differently however is we are not making gambling games and instead making general payments for games and players.  This is to allow new monetisation models in games such as advertising sponsors, micro e-sports, server payments and subscriptions with crypto.
I.e. these will be games of skill typical video games and can even be retro fitted to past titles to rejuvenate their viable shelf life. Basically we want to make it super easy for game developers and game players to use bitcoin.

Firstly... THIS IS NOT AN ICO, this IS BITCOIN based!  We are wanting to do this ethically and with Bitcoin so have it fully backed by Bitcoin.   Yes an ICO would raise the funds faster and easier but we also know the risks of ICOs that they are incredibly difficult to bootstrap any persistent value of a new chain (especially run by a company) hence focusing on the strongest blockchain to express value transfer instead of recreating the wheel.  This means earnings for game developers and game players can be spent globally already using the existing bitcoin infrastructure.


We are still in development and the project itself is using bitcoin testnet only at the moment.  We also good connections in the mainstream games industry around the world from a few of us having spent decades working within the games industry at places like Criterion, EA, Codemasters, etc..

We did a small proof of concept HTML based game so you can see the intended flow here.  (Basically a user can create a bitcoin wallet with simply typing in a display name and ta-dah, they're in the bitcoin ecosystem with a wallet on their mobile/pc)


https://www.bitballbattle.com


You'll need a mate or two to play with (up to 5 can play at the same time), create a round, get some free testnet coins in your account, share the round link with others to play and you can play the game.  Yes the game is crap, that's not the point... the point is the integration is made easy.


In a nutshell, yes this is an authentication based payment system rather than direct P2P.  I have been torn on this subject as we really want to head towards P2P but our mid-centralised approach means we can ensure games are fairer as we can do chargebacks within our system, handle the vast scalability issue games need addressing, instant payments, simplicity aspects and a few other secret sauce features the industry hasn't seen yet.  
Users can always withdraw their funds to a decentralised wallet too if they want to and will encourage this to the players as they exceed earnings... i.e. we are seeing CoinMode as more of a 'hot play wallet' sort of thing to play games in rather than a full wallet... at this stage.  

Why am I sharing this before we are live or accepting real bitcoin?  

Simply, we are raising funds via the traditional investment approach using CrowdCube.  


https://www.crowdcube.com/coinmode

(14 days left as of posting this, completes ~26th May I believe depending on where you are in the world)


This means people can actually buy equity in the company.  For UK citizens you even get EIS tax relief if you're a high rate tax payer.

Whilst we've raised $480k so far there is still ~$160k remaining to be purchased to close the round.

Our plans are to release at the end of the year if all goes to plan and of course happy for any community help should anyone be interested.  (pen testers, authors, game devs, unity tool devs, node/Javascript/docker tool devs all welcome!)


Like I say this is still work in progress, I make no claim this is ready for launch yet but we are getting there.  We are selling equity via regular channels to fund the project properly.  Equally I also am more than aware of the massive hurdles to overcome to making this (how to handle sybil issues, hot wallet woes, bots, GC/FSA/FCA approvals, merchant bank approval, etc..)   We aim to address each of these in a measured way and would love any encouragement/support in making this happen.  

Having global payments for global games seems a no-brainer but bitcoin is hard for mainstream gaming adoption, we want to help make it happen.

What is reassuring is we haven't actually gone out pitching to game development teams yet however we already have some brilliant established game developers signed up keen to use it when the technology is released.

Any questions feel free to ask.



For anyone wanting to invest, have a peek at our promo video on the site and investment starts from as little as £10.

https://www.crowdcube.com/coinmode

Anyone able to contribute to this technical conversation? 

https://www.reddit.com/r/BitcoinTechnology/comments/8bge9c/suggestions_for_using_ln_offline/

Basically looking for ways that LN will be usable by clients or merchants who have no connectivity for a period of time.

E.g. you've gone to some market place or conference hall and there is no cell reception or Wifi.

Thanks,

I tried logging into my old blockchain.info wallet.  It seemed to let me log in with the wallet ID and password all fine and then pops up

"Enter your second password to update the wallet".

Now I know my second password because I wrote it down.  I also have the backup words which I put into their old recovery tool which gave the same password I was expecting.

That said when I type in this password it just says 'no'.

I have my old json.aes wallet backup file that apparently worked with multibit.  I even have my old private keys it generated.

Can I use a new wallet to get this tx history? 

Is there any other way I can log into my original blockchain.info wallet anymore?  I need this because bitstamp is requiring screenshots of the purchase history of that wallet and I'm in a rock and a hard place now.

I have a number of dust transactions that have been sent to my addresses which is just bloating the UTXO set and seems more costly to actually move these into usable money.
Is there any incentive yet to spend these and thereby reduce the utxo set?

I'm sure this has been discussed before but how about we make the rule such that

for every input, if the value is less than say 50x the smallest output the weight/cost for that input is considered 0.

This seems like a win/win for miners (reducing the utxo size) and users (they can gather the dust that may eventually be worth something).

Thoughts?

Title says it all really.  Ebay doesn't seem to allow them anymore (or there aren't any available) so curious where else I could try to buy one 1btc coin from?

How much do they typically sell for now?

Does anyone have any scripts or suggestions on how to test malleability issues in my wallet?

I.e. how do people make sure they handle this correctly?

I'm curious what the RPC approach is to transfer all the funds in a wallet to an external address but with a reasonable transaction fee?

(This is version 0.13.1 if that matters)

E.g. If I have 20,000,000 satoshi balance in the bitcoind controlled wallet and want to transfer as much as possible to a new address but with sufficient fees it's likely to be in the next block, what do I provide to sendToAddress?

I'm trying to keep track of funds that have come in on the bitcoind client but I'm not sure I'm handling the forking issue well so looking for some advice.

What I'm currently doing is when a tx comes in, I store it in my own DB from the walletnotify option that calls my script.
When the tx is confirmed it also calls my script again and I update my db saying it has now been confirmed and can be spent. 
The funds are at a later date forwarded on to coldstorage to prevent any easy hacks.

The catch is, what happens when a fork happens.  At the moment I need to go through and reverse all the transactions that are now in the now orphaned blocks.  This seems a real headache!
I mean do I have to go through and detect that the fork has changed and now reverify EVERY transaction that has ever happened since the dawn of time (or perhaps track which block each transaction was found in)?  What if I've already confirmed it and allowed the funds to be moved, seems like things are going to get complicated quickly.


So my question is, how are enterprise solutions already handling forks and transactions that have previously been ear marked as confirmed and able to spend?

I remember there was what sounded like a sensible discussion on refactoring bitcoind into two distinct modular programs, namely one that does the network/verification logic (bitcoin_node) and another which is the reference wallet (bitcoin_wallet) that speaks to bitcoin_node.

Is this still the plan and/or is anyone already working on it?

Is it possible to get the list of txids that funded a particular address from the bitcoin-cli?  I've had a peek at

listreceivedbyaddress (Seems like this should be the one but I can't pass in an address?)
listTransactions (seems only for accounts and since I'm not using these this doesn't help),
validateaddress( no obvious info relating to txids )
getreceivedbyaddress ( returns only a balance which isn't enough information)

So I've been using bitcore to sync the blockchain on Ubuntu 16.  After running out of space on a 250Gb HD I've moved it to a 1Tb external HD.  It came up with syncing errors so decided to just restart from scratch with this external HD.

The other week it finally reached 100% however a couple days ago I accidentally pulled out the external HD USB lead
I next put the USB lead back in but on a different USB port to make sure I didn't accidentally pull it out again in future.
This seemed to change the mapping from

Code:

/media/myhd/mydir/[b]blockchain[/b]

to

Code:

/media/myhd/mydir/[b]blockchain1[/b]

Argh!  So I changed the bitcore.json file to reflect the new data directory but it gives the following result

Code:

warn: Verifying blocks...
warn: Verifying blocks...
warn: Verifying blocks...
...
warn: Verifying blocks...
error: Failed to start servicees
error: RPCError: Verifying blocks.
<callstack in bitcoind.js>
error: Failed to stop services: Error: bitcoind spawned process exited with status code 1.

I tried adding the reindex=1 into the bitcoin.conf file (Is this the right place??) to try to reindex it but this doesn't appear to be picked up.  Looking in bitcoin.js it appeared as though some help text should appear saying reindexing flag has been noticed.

Anyone know how I can prevent yet another weeks delay in needing to redownload the entire blockchain again??? 

There are no obvious corrupt files on the disk (unlike the disk full scenario which did exhibit this)

I love bitcoin but this setup/usability of bitcore is a nightmare if the db  (not even sure if this is bitcoin or bitcore's db) is really this fragile.  My current concern is when in production if we have a HD crash or power cut we need to somehow fix the db and can't afford to do a full resync each time.

 
I'm pretty sure this is just because I'm new to bitcore and ubuntu but I have no idea how to resolve this Verifying blocks error now so any advice is really appreciated!

Is there any way to speed up syncing time of the initial syncing of the blockchain? 

I.e. copy the chain from a source and tell the machine not to verify the transactions over 3 months old but merely check the blocks and hashes are correct. 

Only thoroughly check the last 3 months worth of transactions via regular p2p network seems far faster approach but are there any security risks with this? (If indeed it is even possible)

(Sorry posted while copy/pasting)
I'm really keen to use bitcore if possible because I love that it appears I can handle HD wallets via my node.js server easily.

That said I'm having a nightmare getting it installed and literally on my 3rd computer trying again and once more hit a wall.

I bought a Intel Duo 2.8GHz machine with 8GB ram, cleaned the 250Gb HD and installed Ubuntu 14.04.


Next I installed as per the instructions here...  https://bitcore.io/guides/upstart-daemon

Code:

nvm install v4
nvm use v4

>Now using node v4.4.5 (npm v2.15.5)

Code:

npm install -g bitcore

npm ERR! Linux 3.19.0-25-generic
npm ERR! argv "/home/bitcore/.nvm/versions/node/v4.4.5/bin/node" "/home/bitcore/.nvm/versions/node/v4.4.5/bin/npm" "install" "-g" "bitcore"
npm ERR! node v4.4.5
npm ERR! npm  v2.15.5
npm ERR! code ELIFECYCLE

npm ERR! bitcore-node@3.0.1 preinstall: `./scripts/download`
npm ERR! Exit status 22
npm ERR! 
npm ERR! Failed at the bitcore-node@3.0.1 preinstall script './scripts/download'.
npm ERR! This is most likely a problem with the bitcore-node package,
npm ERR! not with npm itself.
npm ERR! Tell the author that this fails on your system:
npm ERR!     ./scripts/download
npm ERR! You can get information on how to open an issue for this project with:
npm ERR!     npm bugs bitcore-node
npm ERR! Or if that isn't available, you can get their info via:
npm ERR! 
npm ERR!     npm owner ls bitcore-node
npm ERR! There is likely additional logging output above.

npm ERR! Please include the following file with any support request:
npm ERR!     /home/bitcore/npm-debug.log

Any ideas what I'm doing wrong here?  

Someone posted a libbitcoin C question on reddit's /r/bitcointechnology (https://www.reddit.com/r/BitcoinTechnology) and I'm keen to know the answer as well if anyone has used this lib?
Thanks,

Whilst I love bitcointalk, sometimes it's hard to keep on top of interesting technical articles that come up here and in /r/bitcoin so created a new reddit group named www.reddit.com/r/bitcointechnology.

I'm not trying to detract from bitcointalk and expect people will still be eager to continue posting mainly here but this is more to complement it so there is an archive of useful links to posts here and elsewhere.  At the same time Reddit's awesome tree threading approach to comments instead of a linear thread most forums need to use can prove a massive time saver on helpful threads.

Feel free to x-post anything there if you want to get extra eyeballs on your technical projects, I'm trying to pick out interesting articles to post there but would appreciate any help if others would be interested to post there too.

www.reddit.com/r/bitcointechnology

Can anyone point to some script (ideally in nodejs or php via the RPC to bitcoind) that can read the addresses that have paid funds to a specific address?