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Passwords and authentication

Passwords are omnipresent, but just don’t work the way they should. A password should be a private string that only a user could know. It should be easy to remember, but at the same time hard to guess. It should be changed regularly, and only passed over a secure connection (SSL, ssh). At least, that’s what the password policies I’ve seen say. People, however, get in the way.

I have a friend who always has the same password: ‘lemmein’. She is non-technical. Whenever she tries to sign in to a system, she has invariably forgotten her password. She tries different incarnations, and eventually becomes so frustrated, she just types ‘lemmein’ and, voila, she is logged in.

I have another friend who is a computer security professional (or was). He has the same issue with forgotten passwords, but rather than have one insecure password, he keeps all his passwords in a file on a machine that he controls, protected by one master password. In this way, he only has to remember the one password, yet machines aren’t at risk.

I sympathize with both my friends, since, off the top of my head, I can easily think of ten different passwords that I currently use, for various systems and applications. In fact, the growth of the web applications (since the address bar is the new command line) has exploded the number of passwords that I have to remember.

I’m not as blase about security as my first buddy, nor as together as my second friend, so I just rely on my memory. That works, sometimes. Often, if I seldom visit a site that requires a password, I’ll always make use of the ‘mail me my password’ functionality that most such sites have. I won’t even bother to try to remember the password.

Sometimes, password changes are imposed on you. I’ve been at places where your password had to be changed every three weeks, and must be different rom your previous three passwords. I was only there for a short period of time, but I’m sure that there are some folks who are cycling passwords (‘oh, it’s one of these four, I know it’).

On the other hand, I worked at a place for three years; I had access to a number of web servers, often with sudo, yet I changed my passwords two times. It was just such a tremendous hassle to try to bring all my passwords in sync. (Yes, yes, we should have had an LDAP server responsible for all those passwords; that would have made changing it easier. There are some technical solutions that can ease password pain, at least within one organization.)

Passwords are even used in the ‘real world’ now. Leaving aside the obvious example of ATM pins, my bank won’t let me do anything serious to my account over the phone unless I know my password.

Passwords do have tremendous advantages. They let me authenticate myself without being physically present. They’re easy to carry with you. Computers don’t need special hardware or software to authenticate a user via a password. Everyone understands the concept. But passwords are really the least of the evils when it comes to authenticating remote users (/entities). They’re easy to pass around, or steal, since they’re aren’t physical. Passwords are either easy to forget or easy to crack.

I guess my solution has been to break up my passwords into levels. For simple things like logging into web applications, I have one or two very easy to remember passwords, or I use the ‘mail me my password’ functionality mentioned above. For more sensitive accounts that I use regularly, computer logins where I’m an administrator of some kind, my email, or web applications where my credit card details are viewable, I’ll have some more complicated password, which may or may not be shared among similar systems. And for other systems where I need a good password but don’t use it regularly, I’ll write it down and store it in a safe place.

Passwords are certainly better than using SSN, zip code, or some other arbitrary single token that could be stolen. But they certainly aren’t the optimal solution. I actually used a userid/biometric solution at a client’s office (for the office door) and it rejected me a very small percentage of the time. The overhead to add me to the system was apparently fairly substantial, since it took weeks for this to happen. For situations where the hardware is available and deployed, biometric solutions seem like a good fit.

No one, however, is going to add finger/eye/palm scanners to every machine that I want to access, to say nothing of various interesting remote applications (I want my travelocity!). Some scheme where you login to a single computer that then generates a certificate that uniquely identifies you (something like xauth) may be the best type of solution for general purpose non-physical authentication. But, as a software guy, my mind boggles at the infrastructure needed to support such a solution. Looks like passwords are here to stay for a while.