Yes, both of you are correct.
You don't need to expose or handle raw private keys at all. As I said above, all you need to do is create an unsigned transactions that can be exported as a PSBT and imported in to the different wallets to be signed. The easiest way (but certainly not the only way) to do this is to create a watch only Electrum wallet containing all the necessary addresses. You can move the transaction between as many different wallets as you like in order to sign the inputs in batches or even one by one. 
Topic: Can I make cold wallet off line and has the ability to consolidate the utxo (Read 172 times)
July 11, 2023, 03:00:19 AM
July 10, 2023, 10:41:33 AM
I know the chances are to slim and almost non-existent but there is still a chance that a malicious person could be sitting behind you and taking a good look at your screen while you are extracting tb'he wallet's private key. Again, I know it's almost impossible that someone can remember a private key just by taking a quick look at it, but it's still a risk. Better be safe than sorry.
It goes without saying that you should be doing that in a private environment. Most preferably in your own home where you have some privacy. Working with private keys is not something you should be doing on a shared computer or in a public space. I would, of course, avoid using a phone when out and about as well. 
July 09, 2023, 03:17:47 PM
No. The private keys of the cold wallet will remain offline.
OP should use the private keys of the hot wallet and the cold wallet to create a new wallet on the offline device. He/she should also create a new watch-only wallet using addresses of those wallets.
OP should use the private keys of the hot wallet and the cold wallet to create a new wallet on the offline device. He/she should also create a new watch-only wallet using addresses of those wallets.
No. The private keys of the cold wallet will remain offline.
OP should use the private keys of the hot wallet and the cold wallet to create a new wallet on the offline device. He/she should also create a new watch-only wallet using addresses of those wallets.
Yes, both of you are correct. The private keys will remain on the offline device. I know the chances are to slim and almost non-existent but there is still a chance that a malicious person could be sitting behind you and taking a good look at your screen while you are extracting tb'he wallet's private key. Again, I know it's almost impossible that someone can remember a private key just by taking a quick look at it, but it's still a risk. Better be safe than sorry. OP should use the private keys of the hot wallet and the cold wallet to create a new wallet on the offline device. He/she should also create a new watch-only wallet using addresses of those wallets.
July 09, 2023, 09:20:00 AM
There is no way of signing the transactions on wallet #1 and then proceed to sign those in wallet #2 all in the same go.
Yes there is.Electrum uses PSBTs. This is exactly the kind of thing they are good for. OP can create a watch only wallet containing all the necessary addresses from both his hot wallet and his cold wallet. He can use that to create a transaction, export that unsigned transaction, import it in to the cold wallet, sign the relevant inputs, export this partially signed transaction, import it in to the hot wallet, sign the other inputs, and then broadcast it.
July 09, 2023, 01:27:49 AM
OP can create a new watch-only wallet using funded addresses of wallet 1 and wallet 2 and a new wallet on the offline device using their private keys.
After that, he/she can simply create an unsigned transaction on the online device and sign it on the offline device. In this way, the transaction can be made without private keys of the cold wallet connecting to the internet.
Just as I thought. He would have to export all private keys of funded addresses and combine them all together in a new wallet. There is no way of signing the transactions on wallet #1 and then proceed to sign those in wallet #2 all in the same go.After that, he/she can simply create an unsigned transaction on the online device and sign it on the offline device. In this way, the transaction can be made without private keys of the cold wallet connecting to the internet.
If this is indeed what OP is asking about then the solution you suggested should work. However, although it might be the cheapest solution I don't think it's the safest one since you need to expose the offline wallet's private keys.
The cold wallet remains a cold wallet. It's keys aren't going anywhere. The second wallet was already a hot wallet, so its keys were already exposed to the internet prior to this. hosseinimr93's solution effectively spends all the UTXOs from the hot wallet, consolidates the coins with those in the cold wallet, and creates a brand-new cold wallet. 
July 08, 2023, 05:05:51 PM
If this is indeed what OP is asking about then the solution you suggested should work. However, although it might be the cheapest solution I don't think it's the safest one since you need to expose the offline wallet's private keys.
No. The private keys of the cold wallet will remain offline. OP should use the private keys of the hot wallet and the cold wallet to create a new wallet on the offline device. He/she should also create a new watch-only wallet using addresses of those wallets.
July 08, 2023, 04:49:18 PM
^^
If this is indeed what OP is asking about then the solution you suggested should work. However, although it might be the cheapest solution I don't think it's the safest one since you need to expose the offline wallet's private keys.
Better spend few more sats on safety and consolidate the outputs with two transactions: send the coins from the online wallet to the cold one then consolidate all the outputs on the latter.
If this is indeed what OP is asking about then the solution you suggested should work. However, although it might be the cheapest solution I don't think it's the safest one since you need to expose the offline wallet's private keys.
Better spend few more sats on safety and consolidate the outputs with two transactions: send the coins from the online wallet to the cold one then consolidate all the outputs on the latter.
July 08, 2023, 01:11:36 PM
I think I understand what OP is asking.
I reread OP's post and I think you are right. I have never thought about it and would be interested how that would work myself.
OP can create a new watch-only wallet using funded addresses of wallet 1 and wallet 2 and a new wallet on the offline device using their private keys.After that, he/she can simply create an unsigned transaction on the online device and sign it on the offline device. In this way, the transaction can be made without private keys of the cold wallet connecting to the internet.
July 08, 2023, 12:39:02 PM
If I have fund on cold wallet which is offline, and have watch only wallet on line and another wallet belongs to me on line ,
Can I arrange for utx consolidation? As if I want send fund from my cold off line wallet I make signing on cold wallet then I sign on watch only wallet , could be possible to consolidate utxo as same way
Can I arrange for utx consolidation? As if I want send fund from my cold off line wallet I make signing on cold wallet then I sign on watch only wallet , could be possible to consolidate utxo as same way
A simple way might be to create a new cold wallet with a fresh set of addresses, set up the corresponding watch-only wallet on your online machine, and use that to sweep all the private keys from both wallets into one address in your new cold wallet.
A bit more complicated, but you can also preserve the security of your cold wallet and do essentially the same thing, but all on the off-line machine. Export all the private keys from all the the addresses with UTXOs (both wallets) that you want to consolidate, and sweep them into an unused address from your cold wallet. Make sure the private keys from the cold wallet never leave the off-line machine. Then just broadcast the transaction on your on-line machine.
July 08, 2023, 07:18:58 AM
It's really not clear what you are trying to ask here.
I think I understand what OP is asking.OP has two wallets.
Wallet #1 is a standard hot wallet.
Wallet #2 is a cold wallet with its associated watch-only wallet for the creation and broadcasting of transactions.
Let's assume OP has 10 UTXOs in each wallet, so 20 in total. He is asking if he can consolidate all 20 UTXOs (belonging to two different wallets) at the same time.
I have never thought about it and would be interested how that would work myself. A standard setup wouldn't allow it because his cold wallet doesn't hold the signing keys for wallet #1. Perhaps if he were to export the needed private keys from wallet #1 and import them into his cold wallet (wallet #2) it would work. But then how would he create the transaction across two different wallets on the online machine? Importing the public keys into one of the wallets and only using that wallet for the creation of the transaction? Multisig is different. @o_e_l_e_o thoughts?
July 08, 2023, 02:37:47 AM
Can I arrange for utx consolidation? As if I want send fund from my cold off line wallet I make signing on cold wallet then I sign on watch only wallet , could be possible to consolidate utxo as same way
It's really not clear what you are trying to ask here.Any consolidation transaction you can make via a hot wallet you can make via a cold wallet. If you want to send coins from your cold wallet, you simply create the necessary transaction on your watch only wallet first. Create a transaction sending coins to wherever you want, and consolidate all your other coins in to a single UTXO if you want (just be aware of the privacy implications of doing this). Use your cold wallet to sign it, and your watch only wallet to broadcast it.
July 07, 2023, 04:09:25 PM
Can I arrange for utx consolidation? As if I want send fund from my cold off line wallet I make signing on cold wallet then I sign on watch only wallet , could be possible to consolidate utxo as same way
You don't sign the transaction on your watch-only wallet. Your watch-only wallet doesn't contain any private key and it can't sign transactions at all. You should use your online device (which you have your watch-only wallet on) for creating the unsigned transaction and broadcasting the singed tranaction.
And it doesn't matter whether you are consolidating your UTXOs or you are making a payment.
July 07, 2023, 12:11:35 PM
If I have fund on cold wallet which is offline, and have watch only wallet on line and another wallet belongs to me on line ,
Can I arrange for utx consolidation? As if I want send fund from my cold off line wallet I make signing on cold wallet then I sign on watch only wallet , could be possible to consolidate utxo as same way
what do you mean by buying a paper wallet? like icynote, right? Your wallet will be active in the blockchain network when a transaction occurs. but if your cold wallet is still empty, it will not be visible on the blockchain.
Can I arrange for utx consolidation? As if I want send fund from my cold off line wallet I make signing on cold wallet then I sign on watch only wallet , could be possible to consolidate utxo as same way
Can I make cold wallet off line and at the same time has the ability to consolidate the utxo
what do you mean by buying a paper wallet? like icynote, right? Your wallet will be active in the blockchain network when a transaction occurs. but if your cold wallet is still empty, it will not be visible on the blockchain.
July 07, 2023, 11:25:46 AM
Consolidating your wallet UTXOs is doing an on-chain transactions but you don't send coins in those UTXOs to another wallet of another person but sending it to another address in a same wallet or another wallet of yours. It is consolidation. Best if that wallet has Coin control feature because you don't always want to consolidate all UTXOs.
When you do consolidation, you have to pay fee for that on-chain transaction.
[Guide] Consolidate your small inputs when fee is low.
Creating a cold storage wallet with Electrum.
When you do consolidation, you have to pay fee for that on-chain transaction.
[Guide] Consolidate your small inputs when fee is low.
Creating a cold storage wallet with Electrum.
July 07, 2023, 09:27:41 AM
A cold storage is just a signer and not much else, so the only thing it holds is your keys to sign a transaction you give it. The "consolidation" or generally speaking the handling of UTXOs and transactions should take place in another wallet that is online and does NOT have any private keys (only public keys/addresses) instead of your cold storage. If you try to go around this restriction (eg. manually importing UTXOs) your wallet could stop being "cold" (ie be considered compromised).
July 07, 2023, 08:27:41 AM
Absolutely. All you need is a corresponding watch only wallet on your online computer. Create the consolidation transaction on the watch only wallet as you would on any other hot wallet, export the transaction and transfer it to your cold wallet to be signed, and then export the signed transaction and transfer back to your watch only wallet to be broadcast.
July 07, 2023, 08:18:00 AM
Can I make cold wallet off line and at the same time has the ability to consolidate the utxo
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