title: How to encrypt one message for multiple recipients?
body: <p>What are the fundamentals to accomplish data encryption with exactly two keys (which could be password-based), but needing only one (either one) of the two keys to decrypt the data?</p>
  
  <p>For example, data is encrypted with a user's password and his company's password, and then he or his company can decrypt the data. Neither of them know the other password. Only one copy of the encrypted data is stored.</p>
  
  <p>I don't mean public/private key.  Probably via symmetric key cryptography and maybe it involves something like XORing the keys together to use them for encrypting. </p>
  
  <p>Update: I would also like to find a solution that does not involve storing the keys at all.</p>