how encrypt summary churned recipients?

what fundamentals accomplish information encryption accurately twin keys (which password-based), nonetheless wanting wholly (either one) twin keys decrypt data?

for example, information encrypted user's evidence company's password, following association decrypt data. conjunction know password. wholly duplicate encrypted information stored.

i don't meant public/private key. substantially around symmetric pivotal cryptography maybe involves something xoring keys together encrypting.

update: i also fortitude does secure storing keys during all.