Creating a receiving address and exporting the private keys should be sufficient yes. I don't think It's possible to disconnect/remove a specific address though. If he don't have a PC, he could use Mycelium for android and buy a hardware wallet since the amount is big.
Thanks for the suggestion. He doesn't want me to use any 3rd party to make his wallet. I just tested making a new address and dumping priv key and to my surprise, it was different to my private key. I assumed my made address would be a cold wallet address that linked to the same main address with the same private key. Disconnecting it going to be an issue though. I tried clearing options and reopening the client and it went through first opening routine again (where you choose location to save blockchain etc). I might just re sync the client to another location which should give me a fresh address array, I'll save the private key, xfer funds, and just delete the folder, clear options again and revert back to my folder. Unless there is an easier way where I don't have to re download the 150gb blockchain again?
~ he asked if I could make him a Bitcoin address with my Core client, dump his paid share into it and pass on an encrypted copy of the private key. I said no worries at the time. Now a potential fork is upcoming I want to get it into his own address.
You're using a hot wallet for long-term storage, that isn't a best practice.
I don't think It's possible to disconnect/remove a specific address though.
Correct. All you can do is change the address label to something like "zzzDONOTUSE".
As an alternative, you can create a new wallet.dat before doing all this, so that his new private key is not a part of your own wallet. But it will still be a hot wallet.
Any advice would be appreciated. Cheers.
My advice would be to create a paper wallet (
bitaddress.org). Take all safety precautions: run it from an offline Linux LIVE CD, use a cheap laser printer, don't show anybody the private key and QR-code, and tell him to store it safely.
You could print several backups (more risk of exposure but less risk of losing them), and/or BIP38-encrypt them (safe against theft, but you absolutely must remember the password).
A properly made paper wallet is considered cold storage, a can't be stolen by any online hacker.
Now a potential fork is upcoming
Did you do all this before or after the Cash/Gold forks?
Wouldn't it be a cold wallet if the client nor the key is kept online? How is it different making a wallet from a web wallet over the Core client but adding a trusted party into the mix? (bitaddress.org) The key will be encrypted onto a usb stick and I will keep a copy too just in case. But they will both be offline and cold. Isn't this a cold paper wallet?
I'm referring to the segwit2x repost coming up in a week or was that fake news too? Not interested in all these shitforks.
Would there be an easier way to avoid re downloading the whole chain again as per above? You mentioned the .dat file. If I delete that will it revert to a new address on client open?
Cheers.