I've implemented something similar, but am by no means an expert. Here's my take, experts please correct me! Argon2 was the winner of a password hashing compet

I've implemented something similar, but am by no means an expert. Here's my take, experts please correct me! Argon2 was the winner of a password hashing competition. An effective password hasher "stretches" the entropy of the password. In other words, it maps the space P of passwords to K of keys in such a way that guessing a key requires painful testing of every p. Since |P| << |K|, you need to make sure there aren't tricks whereby you can figure out subsets of K that are interesting and skip the expensive computation. You also need to make sure that hashing is expensive; that there are no shortcuts to blaze through all passwords. (Plus a myriad other concerns, including safely running the algorithm without outsiders being able to figure out the passwords based on timing and such) So now you can take a password, make a key, and encrypt stuff. Guessing the key is hard because trying each password is expensive, and there are too many keys to check them all. Libsodium is a crypto library that simplifies crypto down to "symmetric encryption" or "public key encryption" no mucking around with algorithm and parameter choices, constant time compares, etc. So here your password is securely translated into a private key, whose public key pair they use to encrypt everything as it comes in. The middle step is necessary because argon2 stretches passwords into symmetric keys, but you want an assymetric key pair. So you generate a random key pair and encrypt the private key with your argon2 provided key