NIST drafts new password best practices

NIST is in the process of drafting revised best practices for passwords which are more user-centric.

Anyone interested in the draft specification for Special Publication 800-63-3: Digital Authentication Guidelines can review it as it evolves over on Github or in a more accessible form on NIST’s website.

For a more human approach, security researcher Jim Fenton did a presentation earlier this month at the PasswordsCon event in Las Vegas that sums up the changes nicely.

What’s new ?

What are the major differences between current received wisdom about “secure passwords” and what NIST is now recommending?

Some of the recommendations you can probably guess; others may surprise you.

We’ll start with the things you should do.

Favor the user. To begin with, make your password policies user friendly and put the burden on the verifier when possible.

In other words, we need to stop asking users to do things that aren’t actually improving security.

Much research has gone into the efficacy of many of our so-called “best practices” and it turns out they don’t help enough to be worth the pain they cause.

Size matters. At least it does when it comes to passwords. NIST’s new guidelines say you need a minimum of 8 characters. (That’s not a maximum minimum – you can increase the minimum password length for more sensitive accounts.)

Better yet, NIST says you should allow a maximum length of at least 64, so no more “Sorry, your password can’t be longer than 16 characters.”

Applications must allow all printable ASCII characters, including spaces, and should accept all UNICODE characters, too, including emoji!

This is great advice, and considering that passwords must be hashed and salted when stored (which converts them to a fixed-length representation) there shouldn’t be unnecessary restrictions on length.

We often advise people to use passphrases, so they should be allowed to use all common punctuation characters and any language to improve usability and increase variety.

Check new passwords against a dictionary of known-bad choices. You don’t want to let people use ChangeMe, thisisapassword, yankees, and so on.

More research needs to be done into how to choose and use your “banned list,” but Jim Fenton thinks that 100,000 entries is a good starting point.

The don’ts

Now for all the things you shouldn’t do.

No composition rules. What this means is, no more rules that force you to use particular characters or combinations, like those daunting conditions on some password reset pages that say, “Your password must contain one lowercase letter, one uppercase letter, one number, four symbols but not&%#@_, and the surname of at least one astronaut.”

Let people choose freely, and encourage longer phrases instead of hard-to-remember passwords or illusory complexity such as pA55w+rd.

No password hints. None. If I wanted people have a better chance at guessing my password, I’d write it on a note attached to my screen.

People set passwords hints like rhymes with assword when you allow hints. (Really! We have someastonishing examples from Adobe’s 2013 password breach.)

Knowledge-based authentication (KBA) is out. KBA is when a site says, “Pick from a list of questions – Where did you attend high school? What’s your favourite football team? – and tell us the answer in case we ever need to check that it’s you.”

No more expiration without reason. This is my favourite piece of advice: If we want users to comply and choose long, hard-to-guess passwords, we shouldn’t make them change those passwords unnecessarily.

The only time passwords should be reset is when they are forgotten, if they have been phished, or if you think (or know) that your password database has been stolen and could therefore be subjected to an offline brute-force attack.

 

 

Please see for the full article:

NIST’s new password rules – what you need to know

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