What data are you trying to protect? There are a number of different approaches to this, all of which vary by what you're trying to achieve. You can encrypt cer

What data are you trying to protect? There are a number of different approaches to this, all of which vary by what you're trying to achieve. You can encrypt certain fields generating an encryption key based on non-encrypted data in the row (ex. your key may be sha256(primary key value + create time + application secret), and rather than protecting one master key you must protect the key-generation algorithm). Or you can have one master key that you use to encrypt data - this key should never be written to disk (the key should be decrypted into memory from your key custodians' passwords). Or a combination of both. You should also have a way to version keys so that you can perform key rotation. Certain DB engines allow the entire database file to be encrypted (SQLite offers this with some paid extension, I believe). Or have the user encrypt the data before sending it (as some backup services do). Consult an expert. I could give more details about effective encryption strategies, but I don't want a newbie finding my post, reading half of it, and implementing something dangerously bad. At least no encryption is at a known level of safety; data that's been encrypted incorrectly gives a huge false sense of security.