The most adopted and convenient method of making backups of an HD wallet is by writing down a sequence of words known as the
BIP39 recovery phrase (or simply seedphrase) which when combined form a
seed that derives the masterprivkey and, consequently, the child keys and Adresses.
It is up to you to write down this seedphrase and store it safely in an offline environment, such as on paper, steel plates, etc. Never store it online i.e. in an online notepad or email, because if your computer is compromised, it becomes very easy for someone to steal your bitcoins.
However, if you store it in a physical location such as your office drawer, and someone has possession of this seedphrase and has sufficient knowledge of the importance of this information, they could act maliciously and steal your money. A commonly used solution to avoid this problem would be to encrypt the seedphrase and there are several methods and some of them vary in security i.e some users encrypt a seedphrase with aes, gpg, compression tools like winrar, 7zip protected by passwords (I've done this a lot in the past) and also with
BIP39 Passphrase.
Of these methods mentioned, BIP39 Passphrase is undoubtedly the most used due to it being widely used by hardware wallets, as in addition to being the most secure, it reinforces the entropy of your seedphrase by combining your seedphrase + passphrase generated by you, resulting in a wallet unique access code "hidden" behind that password.
Regardless of the method chosen, the user now has to save 2 information: Seedphrase + password, and in the case of BIP39 Passphrase, the passphrase must always be memorable, as there is no way to recover it if it's lost and it'd only be used if you fully understand how it works.
Some wallets such as Electrum, Sparrow, Bitcoin Core and Schildbach wallet have a functionality to import/export encrypted backups with your wallet's encryption password, and this is very interesting, as in addition to being done in a theoretically safe way, you don't need to resort to other third-party encryption methods that may compromise your seedphrase. With this encrypted digital backup, you can easily make multiple copies and spread them to different locations such as pen drives, SD cards and the cloud.
If you want to make encrypted digital backups, Electrum and Sparrow are one of the wallets that allow you to do this safely, but I leave some observations below:
- There are more than one type of seed: BIP39 and Electrum, BIP39 is accepted in most wallets, while Electrum seeds are only adopted by Electrum.
- If you want to do this on Electrum, your wallet needs to be created on Electrum, as a native Electrum wallet allows Electrum to save your encrypted seedphrase and whenever you need that seedphrase, you can view the backup and make physical copies by writing it down on paper, and a BIP39 wallet that was imported into electrum is not possible, because in this case Electrum don't save the imported seedphrase, it only uses it at the time of import to calculate xpriv/ypriv/zpriv, but if you want, even so if you saving a digital copy of a BIP39 wallet imported into Electrum, you can recover the funds, but your seedphrase won't be saved in the file (unless it's a native electrum wallet).
- If you want to make a digital backup of a BIP39 seedphrase, you can use Sparrow Wallet for this, you can either create a new wallet with or without a passphrase or import an existing seedphrase, encrypt the wallet with a good password. If you need to import your seed to another wallet, you can open the backup generated by sparrow (using Sparrow Software) using your password and view the seedphrase to import into another wallet.
With the tips above, you don't need to risk your security by experimenting with encryption methods that could compromise your wallet. Of course, even if you follow the tips above, but do it on an insecure computer, compromised with internet access, you may still have chances of having your wallet compromised. So the ideal is to do this from an airgapped computer without internet access, preferably a computer just for this that you won't use for anything else.