Bitcoin Forum

All bitcoin money I earned from my freelance services is save from blockchain.info. Are web wallets safe? I tried Bitcore but it says it will took 7days to download the blockchain and its so huge. It will fill my harddrive.

May I know how do you backup your bitcoins? Can you save it from your emails? Google Drive, Dropbox?

Thanks,

It is highly recommended that you not use a web wallet, especially if you have a large amount of Bitcoin.

I suggest that you use Electrum on your computer. You can create an Electrum wallet and send the Bitcoin from blockchain.info to Electrum.

To backup your wallet, all you have to do is go to File > Save Copy and save a copy of the wallet file to a safe location. You will also receive several (13 I think) wallet seed words. Remember or write down these words some place secure as you can use these words to restore your wallet.

Make a paper wallet that isn't so obvious with a QR code private key, and laminate it or something. Send your cold storage coins to that address. Scan the QR code to import when you want to send.

the safest choice is a cold storage, and you can do it easily with Electrum that achow101 suggested. you either need another computer that is always offline or if you don't have that you can use a live linux to create the wallet offline, write down the seed on a piece of paper, double check and shut down the live linux saving nothing else.
every time you want to spend you run the live linux, recover the wallet with the seed and spend.
more info: http://docs.electrum.org/en/latest/coldstorage.html

Use a paper wallet, I posted a step-by-step guide here:
https://bitcointalk.org/index.php?topic=1559277.msg17075677#msg17075677 (https://bitcointalk.org/index.php?topic=1559277.msg17075677#msg17075677)
Print multiple copies if you want the extra insurance against loss or destruction.
Never upload your keys to any web hosting service.
Use paper wallets as "cold-storage", store ~50 mBTC in each one.
Use electrum or Mycellium as a "hot-wallet", break open a paper wallet when the balance is running low.
You can use paper wallets directly to receive payment, I am currently doing this with the address next to my avatar.

hi guys thanks for the response, I have just downloaded electrum. Looks good and not downloading the entire blockchain :)  Will try paper wallet someday.

One more question is the wallet generated by Electrum readable from other desktop wallets?

You and all others should always do a backup of all important things. The how always depends on the form of your wallet. If it is a paper wallet, then have a copy or more at different places.

If you have saved your master seed and now input that master seed into another wallet you should be able to access your wallet from the exact point you have left it at on Electrum.

I very much like the paper wallet idea mentioned above and will start to look into electrum as well just because downloading 100gb will take forever. I suggest people who are running full nodes need to be reimbursed in some way for keeping the system up and running and decentralized! Currently I am using a hardware wallet (Trezor) that will allow me to keep my private keys private and at the same time be able to connect it to a computer with internet connection. Also, no downloading of the blockchain necessary, and there is a back-up option via electrum for Trezor.

Be careful what wallet you choose, for larger amount of bi web wallets are not very much recommended. You can choose some hard wallet which is better option. Also you should back up your wallet, I think every wallet has this option and in emergency situations this could realy save you. I'm not fan of paper wallets because they are not very convenient but from security point of view it's also good option.

Web wallets are not safe none more so than blockchain.info,  they oppose  Segwit  >:( I would steer clear of them

Electrum is using Simplified Validation method it means that whole blockchain is stored online and your wallet is fast as it operates in conjunction with electrum's servers.

Paper wallets are not really that amazing unless you want to research how the process of creating such wallet works or have a lot BTC you want to store safely away.

About importing from other wallets: AFAIK you can't import private keys in a wallet that has a seed. You can sweep them instead.

About exporting: I am not really sure but Electrum seems to be not compatible with any other wallet.

I would just buy a ledger wallet making it near on unhackable and then save the seed in two very safe locations. Job done.

You are right, but I still believe in private wallet for cold storage if you have many bitcoins on it. Of course if you use private wallet , you must spend many days to download and install blockchain but this fact is safe and necessary in the future

Web wallets are not good for storing huge amount of bitcoin. Just use mycellium or electrum wallet. Its offers maximum level of security like cold storage. I suggest use cold storage for huge amounts because its more safety than ordinary wallets. But its up to you also how you keep your btc. Make sure you have a clean computer where you will install your wallet. Having your computer infected with virus can cause losing your btc.

no the wallet.dat file that Electrum creates for you can not be used in any other wallet program. and as far as i know the seed is specific to Electrum itself.

but if a case came up that you needed to do this (which most probably would not) you can always export your private keys one by one and a private key is easily usable in any bitcoin wallet out there that supports importing.
and also there are tools (simple code) that can be used to turn your seed into your private keys.
as i said these are only used in case you could not use Electrum but it wouldn't happen anyways.

I keep my coins on my vanity address created by vanitygen

Use the public key (address) to check coins received on any web explorer.

If need to make a payment I use electrum.

Transfer the coins to the address i am making payment to and the remaining coins to a new vanitygen address.

No web wallets aren't safe to store heavy amount of bitcoin and yeah it may take few days to download official bitcoin client to use as wallet. Easiest option for you could be printing out paper wallet which can be generated offline using bitaddress.org github source code. And don't forget to use offline printer to print it out and save that paper wallet in safe place. Put bitcoin in that generated address and don't store that paper wallet file anywhere online. You can use those bitcoin when you need it by just importing that address to any web wallet.

I use different wallet, electrum, multibitHD and armory. I always get the private key or seed key of the address I use just in case my computer crash and worst scenario, my hard disk is damaged.  
About web wallet, i don't see them very safe because of the possible hack.

Did you use an online vanitygen? I wouldn't trust that as far as I could throw it!
I use Electrum and the seeds are my form of 'back up'

Trezors sounds good, but I fear that a hardware glitch could lose my coins. I have heard that they are still recoverable in this case, but if that is the case, it means that the Trezor icn't really that secure anyway!

Don't click on links, use strong and unique passwords, keep your antiviruses upto date.

Making a back up wallet aside from the web wallet for me isnt working. The   your problem with other wallets it is very risky you may lose it when a virus penetrated your computer, when you forgot your password and many more. So for me web wallet is still the best wallet but the trick is to create many wallets not only in one site but to different sites, that way the risk is distributed and if you lose btc it is only in small portion.

I have just downloaded an Android version of Electrum. How much is the charge if I am going to send money from web wallet to my mobile electrum.

Is there a way to make my bitcoin money from phone synchronized with my bitcoin money in laptop?

Thank you in advance

Bitcoin is becoming precious asset day by day. And demand of bitcoin increasing exponentially globally. While considering these facts bitcoin usr must have to aware about bitcoin technology. Bitcoin wallet is very important for each and every activity. So safety and security of your Bitcoin wallet is most important. Any use can keep back up with .dat file. Or user can simply take back up of private keys associate with your bitcoin wallet address.

Few users have mentioned not to use any web wallet if you have large amount of bitcoin. Better is to diversify the number of bitcoin and save in different wallets. The reason is that than the offline hardware wallets its better to use online wallets for easy access.

OMG YES..

I have it backed up on 10 USBs, 100 DVD's (OH THAT IS RIGHT ONE HUNDERED DVD's),  5 M-Discs and a few paper copies.

Don't mess around back it up like your life depended on it.

Cold storage is safest way if you have nice amount of bitcoin, and web wallet like blockchain.info for tiny amount.

Their are so many reasons of not using web wallets are they are not secure and you are not in control of your wallet address apart from that if you are doing gambling then it is not good as some web wallet block the user account if found using for gambling.

So it is much better to use desktop wallet where you have full control on your wallet address and you can use it any where, i am using Electrum as it is light versions and only remembering the passphrass seed key is enough just safe it to lot of places because with this passphrase key you can reload your wallet any where any time.

You should be able to import a private key or seed into the android version of Electrum, then you can use the same wallet on both devices.
The 'charge' (miners fee) can change but usually it's around 0.0002 BTC.

Indeed that is true but its changing everytime, the fact is that you can easily import it.

I would move your coins ASAP to a hardware wallet. The link in my sig will take you to a place where you can buy these. Hardware wallets are MUCH MUCH more secure than an online wallet. All transaction signing happens in the device so it keeps your coins safe from hackers even on an infected machine. You generate a 24 word seed which you write down on paper, this will restore your wallet addresses and keys as they are derived from this seed.

The ledger HW1 is the cheapest at about £15 GBP, the Nano S allows multiple currencies and has a screen, £50.

Get a hardware wallet, no online or desktop wallet will be as secure. If you really don't want a hardware wallet, download electrum. Make an electrum 2FA wallet, and save the 2FA token and seed.

In normal use, this wallet requires 2 of 3 keys. Your system holds one, another is held at a trusted third party who signs the second on your behalf when you input your 2FA code on your phone. If you loose access to the google auth app and do not have the 2FA written down, the seed contains 2 of 3 keys and this can be used to restore access to your funds, but you must create another 2FA wallet to have trustedcoin again.

Hope this helps, get it out of your online wallet ASAP.

You can use ledger HW wallet on your phone with the ledger OTG USB adapter.

I find electrum 2FA wallets wont work on the mobile app, a normal electrum wallet allows you to import the same seed on both your phone and PC to streamline your access to your funds, this also allows you to have a 'backup' of your seed this way too.

You should use Electrum as it is a lightweight bitcoin wallet. And you can easily backup your wallet easily by exporting your wallet's private keys and seed to a stick for example or if you want to keep it offline make a paper wallet.

Your assumption isn't correct. If a hardware error should appear or you lose your Trezor, you can use the hand written seed and recover the coins just the same as you could with any other wallet using seeds. Just don't ever lose your seed and or destroy/lose your Trezor. Furthermore, Trezor is compatible with electrum and you could recover it by using another Trezor. But hey, no hardware issues for the past two years here.

There is a way to combine public or private keys that commutes with the algorithm for generating public keys from private keys.
In particular, if we have two private keys P and Q, and the function f to generate their public keys:
p=f[P]
q=f[Q]
p and q are the respective public keys.
Call the function that combines keys together "*", it could be a different function when used for public and private keys, but I will still represent it with the same symbol.
R=P*Q
R is a private key produced by combining P and Q.
The function can also be used to combine public keys.
r=p*q
And now for the commutativity property:
r=f[R]
The algorithm for generating the address is a hash of the public key:
p'=H[p]
q'=H[q]
r'=H[r]
Reputable vanity generators work in the following fasion:
1. The client generates a private key P, its public key p=f[P], and sends p to the vanity miner.
2. The client chooses a pattern the address must follow, usually a word it has to start with, and sends this to the vanity miner.
3. The vanity miner chooses an arbitrary private key Q.
4. The vanity miner finds its public key q=f[Q].
5. The vanity miner combines its key with the one provided by the client r=p*q.
6. The vanity miner hashes r to get r'=H[r].
7. The vanity miner checks r' against the pattern, if it does not pass, the vanity miner goes back to step 4, steps 4-7 are the loop, and the miner does them a very large number of times.
8. When an address comes through that fits the pattern, the vanity miner sends the successful partial private key Q to the client.
9. The client combines P and Q to get the final private key R=P*Q, and derives the final address r'=H[f[R]], r' now fits the pattern.
Now the client has a vanity address and its private key, and the vanity miner cannot hack it because P is never sent to the vanity miner.
The only security disadvantage of this scheme is the fact that the public key r is known to the vanity miner, and is vulnerable to quantum computing, hashes are quite resistant to quantum attack, but the number-theoretical elliptic curve algorithm is quite vulnerable. Normally, a quantum attacker only has the time between broadcasting and confirmation to hack ECDSA, but with a vanity address, the hacker can start as soon as the address is generated.
Note that reusing an address that was already sent from, as well as using an address to sign messages, create the same quantum vulnurability as using a vanity address.

How else people should have access to their bitcoins if not backed up? every one should do it no matter what and you should do it first by storing the coins in a virgin address :) and then make few backups on paper and hardware wallet as well. One other solution would be to buy physical coins, but they are still representing an address anyways if one wants to be worried about getting hacked shouldn't even buy or have bitcoins in the first place.

My wallet has a backup phrase that lets me print it off so if I lose my wallet I can restore it and whats in it from that.

Not Online vanity generator but the offline one on PC.

Diversifying and placing in different online wallets will solve the risk of losing. Importantly you need to remember lots of phrases to retain if you lose at some instance due to some technical issues. Now even with advancement wallets were generated as apps to give the comfort and secure accessibility to the users.

Absolutely a must. Depends on the amount you have. I used to back up any amounts lower than 1 btc just as a private key file with a password. Didn't have any issues just saving it on my email.

But in the past for very large amounts, I have backed up using the paper wallet technology.