The good thing is, in 2012 the developer Pieter Wuille designed the BIP32 specification at the base with the hierarchical deterministic wallets. Jointly with it, Pieter created a mathematical purpose to produce a learn key from which to derive all other keys in a very deterministic way. A straightforward backup http://edgargvkh682.theburnward.com/from-mnemonics-to-security-understanding-bip39-passphrases-and-their-importance-in-copyright