Bitcoin Forum

If I set up an Electrum wallet from a brain wallet seed, do a transaction where a change address is created, then delete the wallet file, will the change addresses always be recreated from seed?

I'm concerned after reading this:

http://www.reddit.com/r/Bitcoin/comments/1bd1d1/i_think_i_just_lost_90btc_are_they_stolen_help/

If Electrum acts as I have described above, can someone explain what is different about Multibit that they would have lost their change address private key?  Was a completely new wallet created just for the change address?

Yes, Electrum regenerates all addresses, including change, from the seed.
This is what deterministic wallets are about, and is one of the major differences between Electrum and MultiBit or Bitcoin-Qt (although they are also working to implement deterministic wallets in future versions.)

That guy lost coins because he went the manual paper wallet route. You are relying on a full fledged offline wallet so you won't face this problem if you are careful.

You need two things:

- The seed

- A copy of electrum to recreate the wallet from seed.

Now as far as new change addresses go you might need to give electrum a little hint that it should generate those addresses. It can always do that as long as you have the seed. It just needs a little push in the right direction:

https://bitcointalk.org/index.php?topic=344115.msg3690179#msg3690179

I see, thanks.

So even if the change address does not show up in the Electrum wallet for whatever reason, it could eventually be found/generated deterministically by increasing the gap limit?

Yes it can be found deterministically but not by increasing the gap limit. The gap limit that you can set only affects addresses in the main wallet. The gap limit for change addresses is fixed at 3. So you just run that create_new_address(1) command to generate new change addresses.

But yeah the point is that the seed and a copy of the electrum is all you really need.

Got it, thanks!