Hello,
I could open my old account after I typed myself the password given by the recovery through blockchian.info. Whereas when I copy-pasted my password, the site claimed it was false...
Congratulations!
Once I opened my old account, the site told me that a new ID is generated and I needed to transfer my BTC to the new wallet. It cost 8 USD...
You did not
have to do this. You
could have continued to use the wallet in the legacy mode. But it is an great idea to do it for the reasons listed below. Eventually you will be glad you switched over to the HD wallet.
So now I have a new ID, a recovery phrase of 12 words [which is the seed?],
YES. The 12 words are the seed, the 12 words are everything. From those 12 words you will be able to recover
all your private keys,
all your public keys,
all your Bitcoins on
all your private/public key pairs and your entire transaction history. You do not need to back up your wallet anymore - there is no need to back up since you can recover
everything from those 12 words.
NOTE: anyone can recover everything from those 12 words so never ever never ever lose them, put them on the internet or in any way allow them to be compromised. Anyone who has those 12 words can take all your Bitcoins.
They do not need your password. They only need those 12 keys. This is because all your current private keys and every private key you will ever use in the future are contained in those 12 words.
Keep them safe. a new password. Apparently, this is for a wallet and no longer a BTC address.
12 words -> every private key you will ever use -> every public key you will ever use -> every Bitcoin address you will ever use -> every transaction you will ever do -> your HD wallet
Inside one wallet, I can have several BTC adresses. Before this change, it was easier to manage since 1 wallet = 1 fixed BTC address = 1 password.
Not exactly. Even in the old legacy wallet you could manage many private keys, public keys and many addresses. You just chose not to.
Now here is something you need to know:
In the old wallet, whenever you sent out Bitcoins to someone else, the change from the transaction was placed back on the original address. This was very convenient and allowed you to think you only had and only needed one Bitcoin address. But this behavior was causing great privacy concerns for the
entire Bitcoin system. So...
In the new HD wallet every time you send out Bitcoins to anyone the change will come back to a brand new address calculated from your seed. So do not be surprised when your Bitcoins move to a new address every time you do a transaction. It may take some getting used to but that is the way it works. Since all your Bitcoins are currently at one address you will see the change move to a new address every time you send out a payment for any reason.
I also tried to export my private key, but all I found is an xPub.
You do not need to export your xPriv. Your xPriv can be calculated from your 12 words. Technically this is how it goes:
Your 12 seed words are used to mathematically derive your xPriv
Your xPriv is used to mathematically derive your xPub
Your xPriv is used to mathematically derive all the private keys you will ever use
Your xPub is used to mathematically derive all the public keys you will ever use
Your public keys are used to mathematically derive all the Bitcoin addresses you will ever use.
Cool, eh?
Apparently private keys are obtained through local html page downloaded from github, to convert my xpub key into my private key.
NO. It is
impossible to derive the xPriv from the xPub. You can only derive the xPriv from the 12 words. If someone gets your xPub they cannot get your xPriv and they cannot steal your Bitcoins. However, if someone gets your xPub they will be able to calculate every public key and therefore every Bitcoin address you have ever used, are currently using and will every use in the future. So they would know exactly how many Bitcoins you have and be able to track every transaction you ever do. This is a great privacy concern. So, keep your 12 words and your xPub safe and secret.
Since I do not need a private key so far, I did not do it.
Again, you
have all your private keys now. You
have all your current and future private keys. They are all contained in your 12 words. That is all you need to backup - ever.