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921  Bitcoin / Bitcoin Technical Support / Re: Hardware wallets, missing information in every explanation. Help me understand! on: December 02, 2017, 06:40:44 PM

When are they generated, when I decide one to be generated? Or before I get the device?
How can I confirm that? can I review the source code on ledger, bitbox (not trezor) etc?

To be honest, if people seriously buy a piece of hardware with a preloaded pk and uses that..... oh my. For me that would be like security 101, NOT TO.
Even if I decide to trust the manufacture/company... which I dont. How could i know the ratailer didn't duplicate that key, how could I know that the post mail main who delivered the device didn't unpack my package and duplicated the key? How could I know that some intern in the production factory didn't duplicate the keys etc. 
The keys are generated when you initialize the device. The devices come uninitialized. You can also reinitialize an already initialized device. This will wipe the existing private keys from the device and have it generate new ones.

2. Is it possible to "swipe" the hardware wallet and load your own private keys? And if so, is this easily done?
It depends. If your private keys are part of a BIP 32 HD wallet and you have a BIP 39 mnemonic for that wallet, then yes. You can load the BIP 39 mnemonic onto the device and it will generate the proper keys. If you just have a bunch of private keys that were randomly generated (or you don't have the BIP 39 mnemonic), then no, you cannot.

3. If I can put the hardware wallet in my laptop and send crypto currency stored on it to other address, what would keep a malicious piece of software on my computer from changing the address as I confirm the transaction?
You have to confirm on your device before it signs the transaction. If the outputs are changed after signing, the transaction will be invalid. If they are changed before signing, then you will see the changed address on your device and can tell it to not sign the transaction.

4. Is it possible to; from a totally offline computer holding the private keys. Make an transaction, move the transaction to a usb key, plug that key in a online machine, publish the transaction to the blockchain, so that the private keys never "touches" a machine with internet access.
Yes.

I feel that the info text and video explanations on trezor and legder, bitbox is just showing some little usb thing and showing that "when you plug it out your money is safe" but they never explain the technical background that makes that possible. There is no explanation on why your private keys was not duplicated the moment you plugged it in to your computer, or before you even got the device. And there is no noob safe guide to load your own pks to the hardware wallet.
It is impossible to duplicate the private keys when the device is plugged in as they keys cannot leave the hardware (well they could if you have malicious firmware installed). The firmware for all of the devices are open source and publicly viewable and auditable. If you don't trust the firmware that came with the device, you can install your own self-compiled version. The only firmware that is not open source is the firmware for Ledger's Secure Enclave. The Secure Enclave is where the private keys are stored. However things to and from the Secure Enclave must pass through the rest of the Ledger's open source firmware sop you would be able to see whether the Secure Enclave is leaking your private keys.
922  Bitcoin / Armory / Re: Armory, BCH, BTG and "old" BTC on: December 02, 2017, 06:32:09 PM
For BCH, please read http://fonstavka.com/index.php?topic=2070058.0

Armory currently does not support BTG, so you will need to export your private keys into a wallet that does.
923  Bitcoin / Bitcoin Technical Support / Re: Transactions to Segwit-Wallet gets rejected on: December 02, 2017, 06:29:49 PM
Please post screenshots.

What is the exact error that you are getting?
924  Bitcoin / Bitcoin Technical Support / Re: How to pass raw transaction from cold storage upon hot node? on: December 02, 2017, 06:27:44 PM
Looks like you must use these 2 commands and this second command will automatically choose the correct fee for you?
Yes.

When you open the green icon, I will get the same coins I have on my real wallet.dat but these coins don't have value?
No. Testnet is an entirely separate network. Think of it as an altcoin that has no value. You have to get testnet coins, and there are several testnet faucets. Just google "Testnet faucet" and you will find one that will give you coins to test with.
925  Bitcoin / Development & Technical Discussion / Re: Question about fees and transaction size on: December 02, 2017, 06:25:34 PM
It still is. Bitcoin is good for paying for things that are at least $10. Paying very low amounts (only a few dollars) is not all that good to do on Bitcoin. Nor are credit cards at those low values. Many merchants (particularly Mom & Pop shops or local restaurants) will not accept credit cards if the purchase is less than $10.
926  Bitcoin / Development & Technical Discussion / Re: How do blockchain nodes find each other? on: December 02, 2017, 06:20:35 PM
Some of those DNS seeds provide a static list of IP addresses of stable bitcoin listening nodes.
None of the DNS seeders provide a static list of IP addresses. They all provide a random subset of IPs that are gathered by a crawler. It is against Bitcoin Core's DNS Seeder policy to have a seeder that returns static addresses.
927  Bitcoin / Development & Technical Discussion / Re: New Bitcoin Block Format on: December 02, 2017, 06:12:26 PM
Download the block chain with Bitcoin Core and use a hex editor to look in the files. Or is that too low a level?
Or you could use the getblock command to get the block as a hex string or decoded in JSON.
928  Bitcoin / Development & Technical Discussion / Re: Segwit question on: December 02, 2017, 06:01:25 PM
There are no "extended blocks". Blocks are the same as before; they only contain the block header and the transaction. What changed was the transactions. The transactions have two different formats: legacy, and segwit. When a segwit capable nodes receives a block, it will receive the block with transactions in the segwit format. When a non-segwit node receives a block, it will receive the transactions in the legacy format.

When you run a segwit capable node, using the getrawtransaction or gettransaction commands will give you all of the details of the transaction, including the witnesses.
929  Bitcoin / Development & Technical Discussion / Re: Corrupt wallet.dat, salvage not working, using pywallet.py - Please help :) on: December 01, 2017, 09:54:54 PM
Make sure that the path K:\Bitcoin exists and that your user is allowed to read and write to it. The error is very clear, you did not have the permission to access it.
930  Bitcoin / Bitcoin Technical Support / Re: How to dump a bunch of addresses in empty wallet? on: December 01, 2017, 09:46:17 PM
But the question to move the coins from cold wallet to hot wallet still remains (i mean the transaction), it is very complicated to deal with the rawtransaction specially due fee not calculated automatically as celard posted (I watched the video). Do you have any work arounds achow101? and also hope for gui support for this too in the future, not everyone here is a command line wizard.
Instead of creating the entire transaction by hand, use the fundrawtransaction command. What you do is first use createrawtransaction to create a transaction with 0 inputs and the outputs that you want to have. Then you pass that into fundrawtransaction with the other parameters it takes. It will then choose the inputs to use, calculate the fee, and create a change output if necessary. Then you can take the transaction from that and sign it on your offline machine.
931  Bitcoin / Bitcoin Technical Support / Re: wallet.dat backup on: December 01, 2017, 09:42:32 PM
Thank you. If I generated a witnessaddress and do not know the public key used to generate it, how do I spend funds that are on witnessaddress if I move wallet.dat to another core?
The private and public keys are stored in your wallet. The software will allow you to spend from the witness address.

Also, will my wallet.dat hold the private keys of all my regular addresses? Even if I used the wallet.dat to generate let's say 5, 10 or 25 thousand regular addresses?
Yes. It always does. Keys are never removed from the wallet.dat file unless it is corrupted.

And I suppose that if I have the public and private key of a regular address, I can always regenerate the segwit address and spend all funds that are on that specific segwit address, right? Will the "bitcoin-cli addwitnessaddress 1myregularaddress..." command always generate the same segwit address?
Yes.
932  Bitcoin / Development & Technical Discussion / Re: Why do people hate segwit so much? on: December 01, 2017, 09:35:55 PM
I am also have the question about OP questions.  So i search some possible factors why segwit is not that popular to most of us. Will highlight the important matter.
The problem is that those arguments are incorrect. While they are what people believe, they are also false.

1. SegWit doesnít solve the most urgent capacity issue - SegWit, which is a soft fork solution for malleability, cannot solve the capacity problem.
It does not solve the capacity problem (there really cannot be a solution to that problem though), but it certainly helps. The redefinition to block weight and the lower weight given to segwit spends helps to increase the number of transactions in a block.

Furthermore, by fixing transaction malleability, Segwit enables 2nd layer solutions like the Lightning Network to work much better and more securely. These solutions allow for even more transaction capacity.

2. SegWit will deepen Coreís impact on the community - As an implementation reference for Bitcoin, Bitcoin Core was of significant influence in the community. However, their influence has long been overrated by their actions. By abusing their previous influence, theyíve obstructed Bitcoin block size increase from happening, against the will of the community.
The problem with that is that the Bitcoin Core developers did allow a block size increase to happen. Segwit is a block size increase, and it happened. Furthermore, if Bitcoin were ruled by Bitcoin Core, then Segwit would have activated immediately after it's release, not 10 months later.

3. SegWit makes it harder for future block scaling - On technical terms, SegWit uses a transaction format that can be spent by those who donít upgrade their nodes, with segregation of transaction data and signature data. This means SegWit is irrevocable once itís activated, or all unspent transactions in SegWit formats will face the risk of being stolen.
That is the nature of ALL soft forks, not just segwit. All soft forks are irrevocable once activated, or all unspent transactions that used anything deployed in a soft fork can be stolen. But also any fork that "reverts" segwit (or a different soft fork like P2SH), will just be a hard fork.
933  Bitcoin / Bitcoin Technical Support / Re: Bitcoin Core wallet shows old spent bitcoins from 2012 in balance after sync on: December 01, 2017, 09:30:14 PM
Start Bitcoin Core with the -rescan option. It will rescan the blockchain for all of your transactions.
934  Economy / Exchanges / Re: +44-8004049463 Bitcoin Support Number on: December 01, 2017, 09:28:32 PM
If you cannot find any official documentation or statement from Bittrex that lists this phone number, then it is probably a scam.
935  Bitcoin / Development & Technical Discussion / Re: I've been challenged with a prize of 10BTC to speculate with on: December 01, 2017, 12:12:28 AM
So he proposed to me that he could give me 10 BTCTC, but if I lost it or if "the bubble bursted", I would pay it to him at least two times worth. If I manage to secure it and the value increases, I get half of the profits.
Over what time frame? You had better clarify that, because it could be "indefinitely" or whatever suits your friend.

Anyway, he doesn't really expect to break the blockchain's encryption, I think.
The blockchain does not use any encryption. What you would need to break is ECDSA, SHA256, and RIPEMD160. Those have so far been unbreakable.

What is far more likely is error on your part that results in the coins being stolen. That would be human error, not a failure of the system.


I recommend that you use a hardware wallet or a paper wallet.

A hardware wallet like Trezor or the Ledger Nano S is very secure and the only way to get the private keys is to get physical access to the device, know the PIN, and know the passphrase (passphrase is optional, but you should do it anyways as it is an extra security measure). Assuming you know the PIN and the passphrase, you just need to keep the mnemonic safe. You can do that by storing it in a secure place like a safe deposit box. Note that even if the mnemonic is stolen, if you have a passphrase, your coins will still be fairly safe.

To be absolutely sure that you do not forget the PIN or the passphrase, I suggest that you routinely connect the device to a computer and open up the wallet. This does not leak any private keys onto your computer or compromise your coins security in any way. It just makes sure that you still remember what the PIN and passphrase are.

Alternatively you could use a paper wallet encrypted with BIP 68 encryption. If you do that, you must store the paper wallet in a secure place (e.g. a safe deposit box) but you cannot forget the passphrase. If you forget the passphrase, then the coins will be lost. You should use the encryption as it will protect against anyone stealing the paper wallet. You should also make multiple copies and store them securely in separate places.

I have a notebook that I don't use anymore, with a 320GB hard-drive, so the blockchain fits. I will use a bootable tool to cleanse it's hard drive once and for all, and I won't connect the notebook to the internet until I've got Tails Linux running. Anything I do on this notebook will be for opening the fullnode (or eletrum client) and storing my bitcoins.

What do I need to access the bitcoins contained on my paper wallet? Is Eletrum fully trustable? Is there any way I would lose my bitcoins with it, if used with Tails Linux and taking all the necessary precautions?
Electrum is trusted. However I would not recommend that you use a paper wallet of use an old device to store the coins on. I recommend that you use a hardware wallet. That way you can keep it on your person at all times and verify that it is functioning with basically any computer at any time.
936  Bitcoin / Development & Technical Discussion / Re: How do blockchain nodes find each other? on: November 30, 2017, 08:45:26 PM
Thanks for explanation achow101. Does it mean that DNS seeders (primary and built in) are set of "hardcoded" servers which are basically critical point of bitcoin core and if those servers won't be available whole blockchain will stop functioning (as eventually nodes won't be able to discover each other)?
No. Nodes can still discover each other without the DNS seeders. The DNS seeders can be swapped out with some other initial discovery process too.

Furthermore, as I said, nodes maintain their own internal database that persists across restarts of nodes that it can connect to. So it will use those nodes instead of the DNS seeders on all starts after the first start. For new nodes, new nodes will fall back to the hundreds of hard coded seed nodes.

Lastly, nodes can be added manually too.
937  Bitcoin / Development & Technical Discussion / Re: How do blockchain nodes find each other? on: November 30, 2017, 08:31:27 PM
Bitcoin Core (the most common type of node) has 3 methods of discovering peers. First it consults an internal database of peers it knows about. For a new node, this will be empty. Then it will consult a set of servers called DNS seeders. The DNS seeders give out the IP addresses of nodes that a node can connect to. The node will connect to these nodes only temporarily to gather the IP addresses of other nodes it can also connect to. It will then connect to those nodes. Lastly, if the previous two were unavailable, the node will consult a built in list of seed nodes. It does the same thing with these seed nodes that it did with nodes returned by the DNS seeders.
938  Bitcoin / Development & Technical Discussion / Re: Question about fees and transaction size on: November 30, 2017, 07:35:17 PM
This means that without lightning network, chad shouldn't be incorporating BTC into his business to sell OJ.
No, he shouldn't. Bitcoin is not good for microtransactions and never really has been.
939  Other / Meta / Re: Moving to Cloudflare on: November 30, 2017, 07:00:40 PM
The current Cloudflare solution appears to be blocking bots.

I run two bots that crawl the site periodically, the one for bctalkaccountpricer.info and another one for ACE. Both of these have been blocked from accessing the forum.
940  Bitcoin / Development & Technical Discussion / Re: Question about fees and transaction size on: November 30, 2017, 06:59:14 PM
Alright, so today I was writing a piece of code integrating BTC into my "Business" and I realized a huge flaw with use of BTC economically. Please prove me wrong.

Let us take a small business named Juice4Days that sells cups of orange juice to customers. Each cup is worth 2$ according to BTC/USD exchange rate. Let us also estimate that Juice4Days sells 20 cups of orange juice each day (using only BTC of course). If we assume that BTC/USD exchange rate stays the same, Juice4Days accumulates $14600 in one year on their single BTC address. In one year, the owner of Juice4Days, Chad, decides to send total revenue to his other address for safe keeping. This is where Chad stumbles upon a huge problem:

If we assume that each cup sold was added to Juice4Days BTC address as an input carrying approximately 180bytes of data, we get that the overall size of Chads transaction to his safe keeping address will be 180Bytes x 7300Cups = 1314000 Bytes. According to bitcoinfees.earn.com "The fastest and cheapest transaction fee is currently 0.0000023 BTC/byte", this means that Chad will have to pay 1314000 x 0.0000023 = 3.0222BTC for his transaction.

Chad will have to pay more in transaction Fees than he has made selling his amazing orange juice.

Where did Chad go wrong?  Roll Eyes

Please explain to me, I really want to know how Chad could have improved his system to minimize transaction fees.

P.S Even if Chad pays the lowest possible transaction fee per byte he still has to pay 1236.00 US Dollars. Add to that the possibility that his transaction may never get confirmed.

Chad went wrong by doing two things. First of all, he is using an uncompressed public key. Secondly, he is not using Segwit.

Using a compressed public key itself will reduce the size of each input to 148 bytes.

Using segwit will reduce that even further. A normal P2PKH input with compressed pubkey will be 592 Weight units. With P2SH nested segwit, the input will only be 243 weight units. So with your fee rate of 58 satoshis per weight unit (230 sat/byte is 57.5 sat/weight unit), Chad would only have to pay 1773900*58=102886200 satoshis = 1.02886200 BTC, one third of what you calculated earlier. At the current market rate, he would still be making a profit.

Furthermore, Chad could also wait for the Lightning network to be deployed. If the majority of his customers used the Lightning network and were repeat buyers or routed payments through other lightning network nodes so overall he would have to make very few and small transactions.

Alternatively Chad could also pay a very low fee rate and just wait a long time. If he does not need the money urgently and instead consolidates outputs periodically at a very low fee rate, he would have to pay way less in fees.
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