title: Storing private keys in database
body: <p>I have the need to store private keys for multiple users, so that my server application can sign files on their behalf.</p>
  
  <p>I want to store the private keys securely, but I couldn't find best practices around this. If I was storing a password I would salt+hash the password to make a hash that can't be easily turned back into the password. However, with a private key I need to store it in a way I can later retrieve it.</p>
  
  <p>I was thinking I would encrypt the private key and then store it in my database. I originally thought each key would be encrypted with a different password (based on some properties of the user). However, those properties would most likely be stored in the database, so if my database got leaked then the attacker has everything.</p>
  
  <p>I could encrypt all private keys with a single password that is only known to my application. Then an attacker would have to steal my database, and my application to do any harm.</p>
  
  <p>Is there a technique/best practice I'm missing?</p>