Authentication
Goals
Users associated with an identity should be able to access what they need
users not associated should not
How is it implemented
Something you know
something you have
something you are
Implementing
Store a list of passwords, one for each user
File is readable by root or admin
Why should admin know passwords
If security is breached, attacker knows all passwords
Store something derived from passwords - hashing
Use a one way hash function and store result