I thought so too until I read this: https://bitcoin.stackexchange.com/a/38224/5273

Did you write down the seed words of your wallet? If you didn't then those funds are gone. The private keys that let you spend your bitcoin are derived from the seed so that writing that down makes it possible for you to easily backup your wallet.

The address is not secret information. It is what people use to send you money. If it was possible to spend money using your addresses anyone could spend your money.

If you want to do it on purpose then here's how. It is possible to replace the electrum dictionary with your own custom words. The key point is that the seed you generate with your custom dictionary is valid in any electrum installation even ones with the default dictionary. So create your own custom dictionary and include single letter "words" a..z and then use the make_seed cli command to generate seeds until you get one with a letter "word" in it.

Examples:

any agent cupboard figure taxi error skill tomato rely lawsuit r grief

carbon dial trumpet want ask slam rebuild rival n essay amused mushroom


The dictionary is in /usr/lib/python3/site-packages/electrum/wordlist . You can just appened a..z and 1...9 for instance to the default dictionary.

I am no longer certain that this should be classified as a bug. It's useful for people who make their own dictionaries

If you add k at the end it creates a mnemonic with the correct checksum for a standard wallet. i think this counts as a bug because k is not a word in the dictionary. you should create an issue on github about this.

It could be that you have an old blockchain.info wallet. Drawn is in their old wallet dictionary: https://github.com/blockchain/My-Wallet/blob/master/mnemonic.js . The 12 words are a password reminder mnemonic and not a wallet seed. Since you wrote down the password as well you don't need the 12 words. What you do need is the wallet UUID which looks like a random string of numbers and letters separated by hyphens.

Check your email archive for emails from blockchain.info. If you can find the UUID of your old wallet then you can login with that + your password. Alternatively you can ask them to email you the UUID: https://blockchain.info/wallet/#/reminder if you can guess what email you signed up with.

drawn is there in the old electrum mnemonic dictionary: https://github.com/spesmilo/electrum/blob/master/lib/old_mnemonic.py#L1446 so this might be an electrum wallet. just install the latest version of electrum from electrum.org and restore your wallet from seed as per this guide: https://bitcoinelectrum.com/restoring-your-standard-wallet-from-seed/

Electrum did let you import private keys into an HD wallet. Later they realized that that was a recipe for disaster because users assumed all their private keys were backed up by the seed but the imported ones were not. So they removed that option to import private keys from the GUI when using HD wallets. You can still do it via the CLI though.

A non-HD wallet, such as one created using the import addresses or bitcoin private keys option, can't create new addresses unless you import more private keys into it.

OP needs to clarify how he created the new address.

A large reorg triggers warnings in bitcoin core so people would notice: https://bitcoin.stackexchange.com/questions/38202/can-an-attacker-with-51-of-hash-power-change-old-blocks#comment44888_38224

By blacklist I mean miners voluntarily switching to a different pool from the one that is attacking the network. This would happen at level 0 i.e. the social level.

Yes it is:

https://github.com/spesmilo/electrum/issues/2897#issuecomment-330535625

edit: glad it works for you now

Yes a sustained 51% attack could reverse old transactions. But it would have to be sustained for more than a day. People would notice it and take action to blacklist the attackers.

Did you create the watch-only wallet using your master public key (xpub) or using specific addresses?

At some point it becomes too hard for any attacker to reverse the transaction. 6 confirmations is that mark.

Thanks for the feedback. I will look into explaining what exactly confirmations mean either in this FAQ entry or a linked article.

@howper Electrum maintains backwards compatibility with all previous seed mnemonics so don't listen to anyone telling you to use an old version. Always use the latest version. Old versions have security vulnerabilities in them.

Here is a list of things you can look into.

It used to use .dat extension before 2.0. The OP's wallet is an electrum one or he wouldn't be able to open it in electrum at all.

what is the wallet type under wallet menu > information?

edit: i mean wallet type of the offline wallet.

The transaction hasn't been included in a block as yet. More here

hamburger icon in top right > network > server > choose from peers > choose a different server.

what version of electrum are you using? you can find out the version number by going to help > about.

what is your operating system?

what color orb do you see in the bottom right?

What happens when you try to send the coins to someone using the send tab?