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Secure Private Key Storage for UNIX?
An anonymous reader asks: "Microsoft Windows, from 2000 forward (except ME) offers secure certificate and private storage at the OS level in what is called a protected store. Offline, it's encrypted by a combination of the user's password and a session key stored on the filesystem. When the OS is running, the private keys stored are available to the logged in user, optionally encrypted with another password. The keys are stored in protected memory, so no applications can access them without going through the Microsoft CAPI calls. This code also is FIPS 140-1 level 1 (the best one can get for software cryptography modules) compliant." Does any other OS provide this kind of feature at the OS-level? If so, who? If not, why?
This functionality (especially certified FIPS 140-1 or FIPS 140-2) would be nice to see in UNIX variants. MacOS's key-chain functionality is similar, but stores at the application level, and is not FIPS compliant. An implementation of the protected store functionality will allow applications like Firefox, Thunderbird and gpg to have one common place to obtain private keys and certificates rather than maintaining their own individual key-stores. An additional application for this would be the ability to use hardware PKCS #11 tokens.
I am wondering why this functionality does not exist at the OS level in most OSes except Windows. A number of applications on many platforms have this functionality, but its at the app level, with their own key-stores, and not a standard at the OS level."
I am wondering why this functionality does not exist at the OS level in most OSes except Windows. A number of applications on many platforms have this functionality, but its at the app level, with their own key-stores, and not a standard at the OS level."
on Windows it is centralized and conforms to government requirements because, get this, Windows development is centralized, and Microsoft sell Windows to governments. Amazing huh? Now, of course, if you think this is important, and can code, you might feel like going and writing a daemon for handing out certificates. Hardening it against attack, etc. Then go write the support into all these various programs that use certificates. But unless you're willing to do that, we'll just have to wait until Red Hat, Novell, or whoever go for some government contracts that require this level of certification.
How we know is more important than what we know.
On OS X, the keychain data (certificates, keys, etc) is not managed at the application level. There is a system daemon, securityd, that applications talk to if they need passwords or need data signed / decrypted or if they need credentials for a particular service.
I'm not sure what they're trying to claim here, but unless their definition of OS means "kernel", the Mac OS X (and classic Mac OS, AFAIK) keychain most certainly is an OS-level service. Keychain items can be shared among all applications, though most applications limit access to these items to a list of trusted applications for obvious security reasons.
I don't know about the question of protected memory or FIPS certification, but the rest of this question just seemed like FUD to me.
Check out my sci-fi/humor trilogy at PatriotsBooks.
chmod 600 crypt.key
:)
Just make sure to store the key encrypted with a passphrase
That's odd, OpenSSL was just certified to level 2 (FIPS 140-2).
An implementation of the protected store functionality will allow applications like Firefox, Thunderbird and gpg to have one common place to obtain private keys and certificates rather than maintaining their own individual key-stores.
Maybe it's just me, but I think that putting all your eggs in one basket is not smart. All it would take would be on critical vulnerability to be discovered and all of a sudden a potential attacker can get to all of your keys. Not good if you ask me.
Same idea in KDE, and I'm sure GNOME has a similar mechanism. Whether these are "OS-level" or "application-level" is a subtler question, but this has more to do with the situation that Linux desktop systems don't necessarily have a centrally-planned infrastructure in the manner of Windows or MacOS X, rather than that they haven't addressed this problem at all.
iSKUNK!
OpenSSL was just certified FIPS 140-2, that is NOT however level 2 it is version 2 of the standard. It was certified FIPS 140-2 level 1.
Current versions of the Linux kernel have a key retention feature. For PKCS#11, there is openCryptoki.
An unjust law is no law at all. - St. Augustine
Yes, when there is no actual Microsoft vulnerability available, the crafty Slashdotter can just imagine that one exists, and still get that refershing feeling of superiority!
Er, Lots of stuff lives in ring0, and any vulnerability in ANY of it removes your "protected memory".
You can play games with hypervisors (can protect memory even from 'ring 0') or treacherous computing chips, or things like USB keystores with biometric authentication. But on vanilla 80386 machines, the best you're going to get is the OS to memlock() a few pages so they can't get swapped out to disk.
At the RSA conference three years ago, you could bring your smart card to many booths and they would extract the private key in less than 5 minutes. I have no reason to believe that the problem has become any harder.
True, a smart card (compared to a normal PC) sucks less, but it still sucks.
It's Linux, damnit! Pay no attention to renaming attempts by self-aggrandizing blowhards.
... but what's magical about the "OS level"? According to Microsoft, Internet Explorer is part of the OS, so anything they say about "OS level" is really irrelevant.
We've been mounting home directories on encrypted filesystems for decades, so that's one way to do this. OS X has this built in and very easy to enable.
Which is pretty much how we do this already; just read the file. If the user had a passphrase, use that to decrypt it.
Well, on Unix, no application can access any other application's memory, period. End of story.
There are ways around this -- you could do tricks with kernel memory, or you could read it off the swapfile. However, I believe there is a way to request that a specific chunk of memory never be swapped out, and while it's in RAM, if your kernel's safe, your app is safe. And it's always possible to run without swap, or encrypt your swap.
On Windows, I believe you can "attach" to a running process with a debugger. On Unix, if you want to debug, you have to start the app in a debugger, because once it's running, the app's memory is its own. Only way you can "attach" then is if the app specifically has a way to do that -- for instance, browser plugins are essentially an app deliberately loading code from somewhere else into itself and running it. But if an app doesn't go out of its way to let you in, you aren't getting in, and if your kernel is owned, so are you, even on Windows.
What does FIPS compliance mean?
And once again, "application level" is a pointless distinction. Yes, there are mechanisms for storing keys at the kernel level, but in my mind, that's less secure because it's much more complex for no good reason.
So have them all use libgpg or something. But what is the advantage?
In Thunderbird, I have a PGP key that I sign my mail with, and I have a password that I use to connect to the server. In Firefox, I have an entirely different set of passwords, and the public keys to some Certificate Authorities. Firefox needs none of the Thunderbird keys/passwords, and vice versa. On the commandline, I have an ssh key, which I use to shell in to other boxes -- which is a key that I don't use in Firefox or Thunderbird.
What's the advantage of putting these all in the same app? And what's the advantage of that app being "OS level"?
Ultimately, the only advantage I see is with something like OpenID. It'd be nice if I could use the same keys I use with ssh to gain access to my OpenID server. Unfortunately, I haven't managed to get my hands on a working server implementation of OpenID, so that's moot.
Don't thank God, thank a doctor!
People who need such protection all encrypt whole file system and do not bother with only password/key storage. Linux/UNIX does that for all time I know (Crypto Loop patches is probably oldest patch set for Linux). Windows/Vista I heard can this now. MacOS X allows only to encrypt user home directory what is sufficient in most situations - since keys belonging to user are always saved in user's home directory.
That protection was needed by Windows XP and earlier since it didn't supported FS encryption. And even then people were selling special solutions with transparent hard drive encryption: BIOS asks for password and gives it to the hard drive and Windows goes on booting as usual.
All hope abandon ye who enter here.
Plan 9 has such a central key repository. It's called Factotum, and the best description is the USENIX paper. It has been ported to other UNIX-likes by the plan9port project.
Darren Bane
SanityInAnarchy has apparently not been doing a lot of development in a UNIX environment. While I don't blame him/her for potentially missing out on the ptrace syscall, as it's not mentioned in Stevens' Advanced Programming in the UNIX Environment, I do find it a bit sad that he/she makes such bold statements about the security of a computer system without checking at least the valid command line parameters to one of the tools he is referring to. Luckily an Anonymous Coward already told the world about two of these.
For those not familiar with the ptrace syscall, here is some info about linux ptrace:
Detecting that you're being traced is possible, but it equally possible to circumvent possible detection by tracing at the correct time, deliver spoofed signals, modifying memory in the traced process to avoid being detected. In short: if you cannot trust your system administrator and yourself (at least all processes running as you) you are out of luck as to local security. Network security is one step worse, in that you have to trust even more persons.
Oh, and don't use trustno1 as password!
Geek rants since like... 2000 or something.