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Eight-Character Password Limit in Mac OS X
Qwerpafw writes "While there have been the usual small announcements about Mac OS X security problems, there has been nothing so major as to make me worry about the security of my own box. However, I recently learned that for some reason, Mac OS X only understands passwords of up to 8 characters. Any other characters typed in are discarded as 'garbage.' Well, this worried me, as 8 characters is generally regarded as a rather small keysize, with only 256^8 maximum possibilities (or about 1.845 * 10^19). This is a very real hole in Mac OS X. To make things worse, I was able to find no mention of this at Apple's website, and you are never alerted of this when trying to enter password greater than eight characters." This is generally not regarded a security "hole", and has existed in BSD for many years (though most current BSDs have moved beyond the limitation). It is something to be aware of, and it would be nice if there were a workaround ...
As long as people are careful in the way they make passwords.
Don't use words from the dictionary. Don't use personal information. Do mix up alpha-numerica and uppercase/lowercase. Throw in some punctuation if allowed.
In other words: make it as randon as possible. This will make it more difficult to brute force crack.
Sorry to nitpick, but there are really only about 94^8 combinations (26 upper case, 26 lower case, 10 numerals, and ~32 symbols), which equals 6.095x10^15
The reason is that on most systems you can't simply enter those extended characters.
Let's say we could use any of approximately 96 printable ASCII characters (in actuality, the password may allow non-printable, or international characters)
Also, let's assume passwords must be at LEAST 4 characters (I don't know what restrictions, if any, are applicable to MacOS X).
Then we have 96^8 + 96^7 + 96^6 + 96^5 + 96^4 = 7289831534100480 passwords.
So, assuming about 10% of those are "guessable" by standard dictionary cracking methods (a ridiculously high amount), you have 728983153410048 non-guessable passwords (about 2^52).
That is A LOT to brute force. That doesn't even take into account the use of 'salts' to help discourage dictionary attacks.
So, true, allowing longer passwords would be nice. But it isn't even close to a troubling limitation.
If you need more protection for your data, use mcrypt.
A bigger concern would be if Mac OS X didn't use a shadow password file (anyone?), and if it doesn't at least to a rudimentary check to disallow easily guessable passwords. I assume Mac OS X can be configured to be insecure (boot up into desktop without a password), or more secure (passords required, easy passwords disallowed, etc.)
"It's overkill, of course. But you can never have too much overkill." - Anonymous Slashdot Coward
A "salt" is a little bit of randomness to increase entropy (information content). Say you have a simple password ("apple"), without a 'salt' added. Then someone just needs to encrypt the entire dictionary, which has the word "apple" in it, and compare the encrypted result to your encrypted password. They will easily be able to see that "apple" is your password (because the encryptions match). Note that they only had to encrypt the dictionary ONCE, to detect any simple dictionary password.
Now, suppose that your password "apple" had 12 random bits added to it BEFORE it was encrypted. Those 12 random bits are not-secret (they are published along with the encrypted password+salt). The person who wants to use a dictionary attack on your password has to first look at your salt, and add it to all the words in their dictionary before encrypting and comparing them. Thus, they either have to generate (and store) encrypted dictionaries with all possible salts, or wait until they know your salt to start encrypting. Either way, you given them more work (possibly a LOT more work).
Finally, if they get a thousand encrypted passwords, each with a different salt, they have to do 1000 dictionary searches (one per each unique salt), rather than just one.
So, 'salts' are just small bit of randomness that are added to a lot of cryptographic protocols (and are crucial to certain more advanced protocols), do basically eliminate certain simple cracking methods, without adding much complexity or work for the legitimate users of the protocol.
"It's overkill, of course. But you can never have too much overkill." - Anonymous Slashdot Coward
Old NeXT hands know this because that same weakness existed (and was complained about yet never adequately addressed) back when NeXT existed and NeXTSTEP was actively being developed. NetInfo didn't scale up very well and it never had shadow passwords, two qualities that made it not seem so attractive for local administrators I knew back then. But I'd say this is really just another example of why you should care about your software freedom. After a while NeXT stopped caring about the underlying Unix layer (in NeXTSTEP and OPENSTEP this was 4.3 BSD) and the tools they shipped (an antiquated sendmail that had plenty of holes, for instance) and cared more about things like WebObjects and various high-level "kits" (some of which died before being developed very far).
It was this experience that helped lead me to caring about Free Software operating systems and running only Free Software on top of those systems. Because there I know if there's a hole I can choose to wait for someone to fix it for me, or learn to fix it myself, or hire someone to fix it for me. How much delay I impose on myself has more to do with my willingness to learn about and/or pay for.
Digital Citizen
I tried this on some different platforms and found that Solaris 8, AIX 5 and Tru64 4.0F only use 8 chars.
HP-UX 11 uses more than 8.
I could have done a few more, but our SGI IRIX, Dynix PTX, Sinix and DG-UX boxes are offline.