The exit scam ? You have 2of2 multisig with one vendor, you update the software/firmware , check the signatures, and they steal both wallets' private keys and the company is gone.

Yes, thanks. I've just confirmed that.

However, it may be quite complicated if the trezor firmware updates and then is out of sync with the electrum connection software on the offline machine. Updating and keeping all in sync may become a pain and possibly risky.

Maybe I'm too paranoid. Jumping through so many hoops to get the ultimate security and you lose the coins through complexity.


Btw. I have since found the offline cold storage electrum - trezor does work

It works with the online watch only electrum wallet created with master public keys from electrum and linked to trezor as cosigner. Then when you spend from that watch wallet, the trezor signs, you save txn to usb disk, goto offline cold storage electrum-trezor wallet, connect trezor  to that , load transaction,  it will ask to login to trezor with pin, sign txn on electrum, save to usb, insert usb on watch wallet machine, load and broadcast txn.

All fine as long as you dont have firmware upgrade incompatibilities

I cannot work this out, and are my assumptions correct?

Multisig 2of 2 :

Trezor(say) with electrum (electrum must be online?)
Pros: mix of different vendors/software to prevent exit scam or fatal single vendor bug
Cons: electrum online

Vs

Electrum with electrum multisig, both cold storage
Pros: nothing is online
cons: single vendor

"You should move coins to unspent addresses"

So, if you have some coins in a wallet that you received into an address and then if you spend some of those coins, the remaining coins should be moved into a new address that has no previous coins?

Thanks for this. I am going to try and reproduce what I did, must have screwed something up.

I am now more confident about the prospect of using multisig.

Don't know if this is the correct forum, but I think I found a flaw in multisig. I may be wrong. I used electrum to test.

Setup two 2 of 2 offline multisig wallets. Put some funds in. Setup a watch only wallet as a SINGLE wallet using only ONE of the multisig wallet's master public keys. Initiate the spend txn from the watch wallet, sign txn on the one corresponding offline multisig wallet, broadcast the txn from watch wallet ie a cold storage, offline wallet txn. And it works! You've spent from a 2 of 2 multisig with one signature. I hope I'm wrong!

The point is that I spent the coins of the 2of2  multisig wallets with 1 sig. Regardless.

Either my multisig  wallets are setup incorrectly(still possible, but I cannot see how), or there is a bug in multisig.  

The fact that watch was setup incorrectly is immaterial. You should never be able to spend from a 2of2 multisig with only 1 signature. Period.

If the cause of this bug is setting up an incorrect watch wallet, then that should be fixed. An attacker can purposely then setup an incorrect watch wallet and steal coins, maybe from any M of N wallet  with just one sig from any of the wallets ?

Are you the posting police ?

You half answered my question. Nobody has answered the question fully IMO and it looks to me like a serious security hole.

You said IF I setup my watch correctly with 2 xpubs THEN it will work correctly. Granted, that's correct and I did make a mistake there. But an attacker does not have to do that. They setup watch with 1 xpub , as I did, and then only required 1 sig to drain from both offline 2of2 multisig wallets ! What's the answer to that ? That's quite serious IMO

I set up the offline multisigs correctly, because it says 2of2 in each header and 2of2 of the default multisig in electrum. I apologise in advance if I have made a setup or assumption error, but I don't think so.

Except both multisig wallets have "2of2" named at the top of each wallet, and I checked again the default wallet when creating a multisig in Electrum is 2of2 requiring 2 co-signers(your 2nd image). 

I will just give multisig a miss until I am more confident in it.

I am lost sending coins from this multisig wallet.

I use an online watch wallet to create an unsigned send txn, save it to a usb drive.
load unsigned txn into multisig1  , sign it , save and export to usb drive.  (what is the difference between save and export ?)
load signed txn into multisig2. There is no sign option(greyed out) then what ?

I got it to work once after much fiddling, but not sure how to repeat. It is completely un-intuitive and unhelpful IMO.

Update : It gets worse, I tried 3 methods to send the coins , all 3 different, all 3 worked, at least 1 was wrong(1 sig) it still confirmed. Now I'm worried ! I conclude that this does not achieve 2of2 in electrum. You can pretty much do anything as long as you have at least 1 sig, it will confirm.

PS : It says 2of2 at the top of each wallet and I used the other's key to create each multisig wallet respectively. Presumably they are correctly setup.

Test1

1. Online watch wallet-send txn , export to usb
2. Offline multisig1 wallet-load unsigned txn,  sign, save, export
3. Offline multisig2 wallet- load unsigned txn, sign, save, export(this overwrites the prev signed txn file from multisig1 wallet )
4. Load signed txn file from step 3 onto watch wallet and broadcast

Test 2
Only signed on 1 multisig wallet and then broadcast from watch wallet. (sent and confirmed only 1 signature !)

Test3

1. and 2. are the same, but 3. I just loaded the signed txn and then saved and exported it back. Sign button was greyed out.

Good suggestion. Thanks

Wallet frozen with funds. Asked them about 8 times over past month, never replied with a reason. Never replied period ! Lucky it was not much funds, you may not be so fortunate. Eventually with further BTC adoption and LN, we won't need these cretins.

AVOID !

Because if you manipulate the markets it's essential that you co-ordinate the movement of both markets in the same direction , for max effect. No use selling the futures market and the bitcoin market moves in the other direction. It may move opposite in any case , but they may  attempt to time the move in both markets for max effect. The futures market is just a sentiment magnifier.

Also, who knows, they may attempt to set the bitcoin price in the futures market. Making it "official". As they do with gold. The gold spot market has been hidden from public view.

The difference in the bitcoin market, unlike shares or gold markets, you should be able to easily take delivery of your bitcoins so that they cannot be loaned out from underneath you. Except exchanges make it difficult and restrict withdrawals.

It's very hard to prove,  but it is long been suspected to happen in the gold market.

What makes me suspect it is the limit on withdrawals on bitcoin And the fact that the futures is settled in cash , not bitcoin.

Coins laying on exchanges can be borrowed and sold short driving the bitcoin price down.  If the furures are also shorted then huge profits can be made by those with deep fiat pockets and the bitcoin market can be whipsawed and made to scare off investors.

Even if they say they don't lend your coins on the exchanges, how would you ever know ?

 The danger is a whale can buy short futures. Then he sells all his bitcoin. The price crashes as other sellers exit, he covers his shorts and buy back all his btc. This is how markets are manipulated with futures. And it's about to happen with btc. Bitcoin has been free of wall street manipulation until now.

You have been warned!

 And where are they going to get the huge amounts of bitcoin to sell short and crash bitcoin. ? From the exchanges ! Remember big exhanges  restrict withdrawals and they signed the New York Agreement for sw2x. ie.They have indicated their desire for centralized control.

People MUST get their coins off all exchanges!