The good thing is, in 2012 the developer Pieter Wuille developed the BIP32 specification at The bottom of the hierarchical deterministic wallets. Jointly with it, Pieter produced a mathematical purpose to produce a master critical from which to derive all other keys inside a deterministic way. This information explains BIP39, http://remingtonjszi611.almoheet-travel.com/from-words-to-wide-range-how-to-efficiently-use-bip39-passphrases-for-your-copyright-wallets