Bitcoin Forum

I want to know something important , I'am really struggling with this Bitcoin Core because each time I close it and re-open it , it tells me that the data has been corrupted on the database and I need to do the reindexing another time which sucks and it really takes a lot of time (UP to two days sometimes).

So my question is can Bitcoin wallets goes down ? I mean Armory & Electrum & Multibit mostly , I know they are open source but do they need server connection or something ? I mean if there servers goes down are we going to be able to them or our BTC will be lost forever ? (Unless we still can run them to export private keys , not sure how it works) same goes for Bitcoin Core it can go down or it can't ? :o just want to know if they rely on a server or something that can be hacked .

I'm only familiar with Electrum and QT. Basically if all of their servers go down you just open the wallet and export the private keys.
It's pretty simple, however I still prefer using Bitcoin Core. You can never encounter such a situation with it. Anyhow, the chances that all Electrum servers will go down at once is very low.

Armory connect to local Bitcoin Core and it does not need any server to send/receive Bitcoin.

Electrum connects to servers created by others and it is very unlikely for all the servers to go down. However, if such a situation arises, you can use your seed to recover Bitcoin.

Obviously, Bitcoin survives because of full nodes and for that, currently, either Bitcoin Core or Bitcoin XT needs to be run. So it can't.


Only Electrum need server but private keys are stored locally. So you don't need to worry!


Which OS and Bitcoin Core are you using?

That's all I needed to know because Bitcoin Core eats shitload of CPU and I can't run multiple things on my PC while running and wanted to switch so just checking .
for what comes to your question Muhammed Zakir then I'am using Windows 8.1 Proffessional 64 bits & Bitcoin Core version v0.10.0 (64-bit) . Yes I didn't do the last update for my wallet since I'am waiting Windows 10 in three days and not sure if I'am going to stick with Bitcoin Core or go with Lightweight wallet . any advices are appreciated though.

But I don't think that the problem on my issue is having the 0.10.0 version since It was stable , nah ?

some times it do this at random, the issue would have to do with antivirus but it is not certain, for example i know that with malwarebyte and hitman pro it work great because i'm running those two with bitcoin core, try to run the last version just to see if it fix your issue

I'am not sure what that Hitman pro is but I'am using Malwarebytes and it's not working great (If it have any relation with it of course )
I keep having all those issues with the Core which makes me think I may be infected and that's why I wanna wipe PC as soon as Windows 10 comes out , also as you see here , another problem i had : https://bitcointalk.org/index.php?topic=1129075.0

Every program (online or in your computer) van go down. The problem is if it will be restored after or not. If hardware in your computer it will be damaged physically your program it is gone forever. But you can backup its important data and so you will not lost anything or only a few things (the time passed from the last backup). While the online programs normally made backups every hour so nothing can be lost.

This is worth for the bitcoins wallet too. If they will go down they will be restored and nothing bad will happen.

http://bitcoin.stackexchange.com/a/12206 might be helpful to you.


http://www.surfright.nl/en

Gracias Muhammed once again but you just made me afraid more then ever.
If I have Hardware issues , does that mean that wallet.dat could get corrupted at one point and I won't be able to restore my Bitcoins ? or what wallet.dat is nothing completed just some strings that can be viewed with HEX or something ?

Yes, it can happen but as long as you make a backup if your wallet.dat or private keys, you are safe.


http://bitcoin.stackexchange.com/a/3177

http://bitcoin.stackexchange.com/a/35580

Don't forget that anything that runs in electricity can go down. That's a scary part about Bitcoin, it doesn't survive a societal breakdown where ppl are "off the grid". What happens to the block chain in that scenario?

It brings new meaning to "cold storage"!

Lighter and decentralized alternative is using an SPV  (https://en.bitcoin.it/wiki/Thin_Client_Security#Simplified_Payment_Verification_.28SPV.29_Clients)wallet. SPV wallet query directly to full nodes, and doesn't rely on any centralized server.

Currently the most prominent one is Multibit Wallet. Others options can be found on the wiki (https://bitcoin.org/en/choose-your-wallet)

There are two types of wallets. SPV wallets do not verify the blockchain and depend on a decentralized service on top of bitcoin to verify. If that decentralized service on top of the blockchain goes down you cannot easily send your bitcoins from that wallet to another. You can mitigate this risk by creating nLockTime (https://suredbits.com) transactions. Full node wallets (i.e. Bitcoin core) run on the actual blockchain and cannot be taken down unless the entire bitcoin network goes down.

They can't go down, but they can fail to connect to the internet, or the data stored by them may get corrupted, if the there are hard drive issues or if you deleted some files or if you installed a corrupted version of the wallet.

Try to reinstall and check disk integrity, if you are sure the wallet can receive and send connections

I would suggest using bitcoin core now... its fast, easy and without additional risks like when using multibit with hidden fees in each transaction with deanonymization for free, or electrum where server can know all your transactions.

For the decentralized bitcoin network to go down, means entire bitcoin nodes are down. It cannot happen, as this would
require switching off or unplugging every full node from the internet.

I'm pretty sure that retrieving my private keys will be the least of my worries in such a scenario.   That's why having gold is good to have as a backup investment.

back ups are made for a reason, you cna buy a powerful apc smart ups of 1500w and be safe for a very long time up to 1 hour, it depend how much you consume

so if every miners has many of those(a bit expensive but feasible) they cna in theory be online when a black out goes live

I'am really struggling to find out the solution here , for Bitcoin Core as I said I have issues with it and I'am afraid that my wallet.dat is corrupted or soomething and it eats a lot of CPU & RAM and can't handle that because myPC have only 3GB RAM and that's too low for Bitcoin Core . Multibit HD don't have hidden fees AFAIK , they tell you that they will send x satoshi's to the developpers of the application + the fees of the transaction for the miners or whoever takes those .
For what comes to Electrum , people just said it's decentralized so how it pass by a server :o

Electrum client doen't directly interact with the bitcoin blockchain. Decentralized in the sense that
people are independently running electrum server (http://electrum.qc.to/).

Official Infographics of Electrum about its network
https://electrum.org/slides/network.png


On the bottom of main page of their wiki (http://electrum.orain.org/wiki/Main_Page), you can see, how to setup electrum server

Ty money.investement and what if I run Electrum server what exactly would happen , I was also checking their github and look what I found , does that means that versions from 2.0 to 2.3 was hackable before ? (Check the bold text) *Paranoid*

You need to run bitcoind (daemon) / full node for doing public service of running electrum server.




Was only hackable, if you sent payments to domains, using OpenAlias DNS records (https://openalias.org/#about).

3 GB is actually not "too low" for it, my servers runs it fine with only 2GB. I suspect that your overall system is quickly eating up the 3 GB. I dont think this would improve with Win10.


No the fees are not hidden, but you pay a little to the devs for every TX you create. You have to decide whether this is something you are willing to do or not.


Its not a single server, but a multitude of servers. Similar to bitcoin core. By default a random server is selected every time you start the wallet.

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IMHO your best course of action now is

#1 secure your coins, create a backup (if you dont have one already) or a paperwallet (if you prefer)
#2 figure out as best as you can what is actually wrong with your system and whether parts need replacing
#3 test several wallets to find the one that suits you best. MB and Electrum are only the most common ones. There are new wallets you might prefer over these. I think the "choose your wallet page" was already linked, if I am mistaken. here -> https://bitcoin.org/en/choose-your-wallet

Look Shorena , I know Paper wallet is the best option probably . but I'am too paranoid (like so much) I was reading this Tutorial on CoinDesk how to make one so I don't make any wrong things I may regret later http://www.coindesk.com/information/paper-wallet-tutorial/

I decided to use this website , I turned the modem off so I'am totally offline and download the Github on their page .I printed then ... I throw the paper . I was too paranoid to find out after 5 years for example that the Adress on that Paper dosen't match the private key . also on Paper wallets should we write the private key by hand ? when we import them to another wallet ?

I'm pretty convinced that writing is better than copy/paste and printing. I would not be surprised if your printer stored your private key.
Well, I actually did a better (manual method), if you already have been using QT for a while. Using coin control within the wallet itself, I've transferred everything into a single address. I generated its private key, wrote it down a few times and overwrote the wallet.dat 35 times (most secure delete - unnecessary, but since the file is small this is pretty quick). If you're into the design of paper wallets, you could try finding a empty one and printing it.

As stated in the article, there are some security concerns.

I hope I'am not annoying anyone here honestly ; Another question and option I may do too which are brainwallets. is this the website where I should do that ? https://brainwallet.org/
All I need to do is a passphrase ? Copy the adress so people send there and that's it ? when I want to send I just need to type the passphrase once again on the website and my Private key should showup then Import it ?? I know I should download it from Github and do it Offline .

What does someone need to crack the wallet basically ? Is it even possible to crack the password if it's hard to guess . People that know me from the internet don't really have much informatinos about me to guess the password and IRL people don't know what Bitcoin is , so it's all about cracking ,how easy or hard is it ?

Also what is "compressed" & "Uncompressed" options :o

This is essentially how it works, yes. The biggest concern with brainwallets is that humans are very bad at generating something random and thus many brainwallets are already generated and watched. Dont let that stop you however, just think about it befor you do it. I suggest reading at least this thread by CIYAM -> https://bitcointalk.org/index.php?topic=885616.0


Your password/passphrase.


Its hard to say how hard it is without knowing enough about it to make it easy. To give you a general idea of how strong a password can be -> https://blogs.dropbox.com/tech/2012/04/zxcvbn-realistic-password-strength-estimation/

To every private key there is a public key. This public key can either be the full 65 bytes or compressed to 33 bytes. Since the address depends on the public key a compressed public key leads to a different address than an uncompressed one. You need the same private key to spend the coins though. Most are compressed now since it reduced the size of the TX that has to include the public key to allow verification of the signature.

I understand how hard it could be to generate such passwords however how that brainwallet website works ? does it generate based on the key or based on the letter & the number written ? because if I use other language (like russian) won't that make it harder to get cracked ? :o

It takes the SHA256 value of your phrase, e.g. SHA256("0") = 5feceb66ffc86f38d952786c6d696c79c2dbc239dd4e91b46729d73a27fb57e9 and uses it as the private key. A private key is a 256-bit number in a certain range[1]. You could use a different algorithm that ends in the same range of possible solutions for a given input or you could even directly generate the private key as a number (in your favorite format). Its just different ways to store the same information. A less common language - which I would argue russian is not - is believed by some to help, but there are pretty scary stories[2].

[1] https://en.bitcoin.it/wiki/Private_key#Range_of_valid_ECDSA_private_keys
[2] http://www.reddit.com/r/Bitcoin/comments/1ptuf3/brain_wallet_disaster/