Bip39 Vs Bip44 One illustration of manually generating entropy could be flipping a coin. But if an attacker provides a coin that may be weighted marginally in favor of heads, your First source of entropy could have been corrupted. They do not keep instantly private data, but are determined by https://socialtechnet.com/story4073564/bitcoin-seed-phrase-generator-5-essential-elements-for-bip39-word-list