Bip39 Checksum. The passphrase isn't selected from the predefined list of 2048 words – it might be any word or phrase you select. But certainly, the ultimate barrier is you. Your seed phrase may be the master critical in your copyright wallet, so you should definitely don’t hand it out. https://getsocialsource.com/story4582562/bip39-words-https-linktr-ee-bip39-not-known-details-about-bip39-list