Bip39. The passphrase is not chosen from the predefined list of 2048 words – it can be any word or phrase you choose. But obviously, the ultimate barrier is you. Your seed phrase will be the master key for your copyright wallet, so be sure you don’t hand it out. https://bookmarkforce.com/story18855137/bip39-mnemonic-https-linktr-ee-bip39-the-best-side-of-bip39-mnemonic