Importing a private key can lead to non-intuitive behaviour, and that can be exploited by an attacker.
Imagine I'm evil. I give you a paper wallet with 1 mBTC on it. You're happy and import it. I keep the private key and wait. Depending on the client/user, maybe someday you'll put some real money on there as change/received funds. Then I can swipe them ...
Key import by itself (from a trusted source of keys, such as your own cold storage or backups) isn't a dangerous thing. However, the vast number of ways one can cause problems for themselves through key import leads to these warnings.
Many such warnings appear to address more complex situations beyond bitcoind's scope. In this case, there can be many ...
WARNING: While this answer may be a solution to the issue in the question, it involves exposing your wallet seed to a tool on the internet. Please be very careful when doing this!
Can't add comments so extend Chris.J's answer:
Here are my notes on how to recover / rebuild / regenerate / extract ALL addresses and keys used by MultiBit HD:
Go to https://...
Edit: Answer to the question: How to get private keys out of Bitcoin Core
After you found your addresses (by using the commands I listed below, for example) you can execute the folllowing command:
If your wallet is password protected and locked run:
walletpassphrase "your password or passphrase" 600
And 'walletlock' when ...
In case you have a beta7 wallet which is not BIP32 compliant you cannot use the method @chris-j has put forward.
The easiest way for me was to hook into MultiBit HD's signing capabilities and log the private key being used to the console:
diff --git a/mbhd-core/src/main/java/org/multibit/hd/core/managers/WalletManager.java b/mbhd-core/src/main/java/org/...
Response to clarified first part
You're pretty close, I suspect you want something simpler like this (and then typing in the xprv you extracted from an Electrum 2.x (unencrypted) wallet file):
bx hd-private --index 2 --hard | qrencode -o - | feh -
In particular, don't include the bx hd-to-wif step, that's probably what's tripping you up.
When you do the ...
The problem is rather subtle and results from a combination of behaviors.
First of all, it is perfectly safe to use someone else's private key, at least in a standalone sense. Suppose the private key is P and the public address is A, and suppose you want to spend their money. Then you scan the blockchain for transactions outputs that are addressed to A. ...
If Eve gives you a private key that contains Bitcoins in exchange for a pile of gold coins, she still has a copy of the private key, and can take the Bitcoins back, leaving her with both the gold coins and the Bitcoins.
Instead, tell Eve to send Bitcoins to your address.
Because the private keys and addresses are created deterministically from your wallet words you just need to keep your wallet words safe - there is no need to expose individual private keys. You can use your wallet words to recreate your wallet in either MultiBit HD (use the Restore button on the 'Enter password' screen) or using other tools.
For instance, ...
I suspect you can import it directly from the console within Electrum (based on this PR). Currently, Electrum does now allow importing individual p2wpk inside p2sh addresses (the 3 segwit addresses). You can, however, still import an entire seed by using a BIP49 derivation path.
Try running the following in the electrum console:
key = 'your_key'
Your QR code contains your private key, but yes you can recover with the private key directly if the QR code is now physically damaged.
I do not see that option for blockchain.info (which you stated you are trying to use in your comment):
https://blockchain.info/wallet/import-wallet supports QR codes Bitcoin-Qt (wallet.dat) and blockchain.info (wallet.aes....
MultiBit developer here.
You'll need to use MultiBit Classic version 0.5.19 available as a download from the site https://multibit.org. This will allow you to open the .key file and synchronise with the block chain to recover all the funds associated with the private keys held in the file.
Once you have imported the keys, we strongly recommend that you ...
Yes. txindex=1 is not related to the wallet and the wallet does not know about the txindex nor does it care. What the wallet really cares about is transaction output information and which transactions are related to addresses stored in the wallet. The txindex does not store any of that information, all it stores is the location of each transaction identified ...
Exodus eventually answered this questions themselves, with a similar answer to that given by @McLeodX but specifically discussing import of BTC private keys rather than sweep or transfer.
In short, export BTC private keys from Exodus, import them into Bitcoin.info wallet, then use bitcoin.info to do future transactions with fees that can be adjusted.
I am ...
Perhaps a distinction between importing and sweeping a key needs to be considered. The aforementioned warnings deal with the importing of keys, and does not refer to the sweeping of keys, which moves all the coins to a new address. This method is inherently secure.
On Bitcoin-QT can use whatever change address you want. Go to Settings->Options->Wallet and check "Enable Coin Control Features". Now when you go to send you can check "custom change address" and enter whatever you want, even if you don't have the privkeys.
Meanwhile I've answered this question at reddit.
You have already taken the first 2 out of 3 steps necessary for your wallet migration: (1) cleaned up the data directory that contained old incompatible files, (2) dumped and imported the private keys from the old wallet (alternatively, depending on how old the wallet is, one could try starting the new ...
All your addresses and private keys in MultiBit HD are produced from the wallet words that you are given when you create a wallet. (This is why it is so important to write your wallet words down).
Because everything is generated from one thing the randomly generated private keys in MultiBit Classic cannot be imported into MultiBit HD.
The safest way to ...
The sweep function will send all coins related to the imported private key(s) to a new address (from the deterministic wallet). After sweeping, the private key is no longer capable of spending coins.
There is no need to "import" the private key in advance.
Mind that you need to pay a fee for the sweeping transaction (which is very little).
WARNING: While this answer may be a solution to the issue in the question, it involves exposing your wallet seed to a tool on the internet. Please be very careful when doing this, since
...just DON'T DO IT!
You probably don't know the guy behind the web page well enough to trust them with your precious bitcoins.
Even if you do, the site may have ...
After lots of suffering I managed to do it. Very unfortunately mycelium does not even support importing their old keys.
Fortunately they provide a backuputil which converts the private key in their format into WIF (Wallet Import Format): https://github.com/mycelium-com/wallet/tree/master/backuputil
I takes some effort to built this tool but afterwards you ...
go to help-> debug window -> console
walletpassphrase "your walletpassphrase here" 60, to unlock the wallet if its encrypted.
dumpwallet "filename", will crate a plain text file in same directory where your wallet .dat file is form which you can get your xprv.
walletlock, to lock your wallet
Don't forger to erase the file after you get the ...
I closed my Exodus account for the same reason. The worst case was with Bitcoin with a $200 transfer fee! Of course it goes to the miners, but Exodus doesn't allow you to reduce it. Exodus makes their money by taking a % on exchanges.
I found BitcoinCore the most economical for Bitcoin. You can set the transaction fee as low as you like. Since I am just ...
The entire process is as follows: (these instructions are correct for Electrum v3.0.6)
Install Electrum. The installation methods vary but, the official download is here. On some varieties of Linux it is in the default distro repository.
Choose Automatically Connect and click on Next.
Name your wallet if you like or accept the default and ...
First, confirm that you did indeed receive a private key. On Bitcoin mainnet, private keys are almost always distributed in a format that starts with either a K or an L (capitalized in either case) and are usually 52 alphanumeric characters long. Here's an example:
If you instead received a code ...
When switching wallet providers/programs, the safest option is to usually just send the BTC to the addresses provided by the new system (after you have made a backup of the mnemonic phrase/keys for the new wallet).
Although standards compliant wallets should be able to accept each other's seed phrases, a wallet restoration process is an inherent weak point ...