Slashdot Mirror
Resisting the PGP Whole Disk Encryption Craze
alaederach writes "I run a lab in a non-profit academic life sciences research institute. Our IT recently decided it would be a good idea to use PGP whole disk encryption on all of our computers, laptops and servers and picked PGP's suite of software. The main reason is that a small subset of our researchers work with patient information which we obviously are mandated to keep confidential. My lab does a lot of high-performance computational work (on genes from Tetrahymena, no humans here) and I am concerned that the overhead of complying with our ITs new security policy will be quite detrimental to my research program. For example, dynamically reallocating a partition on a PGP encrypted disk is apparently not possible. Furthermore, there is some evidence that certain forms of compression are also incompatible with PGP whole disk encryption. Interestingly, it is hard to find any negative articles on PGP, probably because most of them are written by IT pros who are only focused on the security, and not usability. I therefore ask the Slashdot community, what are the disadvantages of PGP in terms of performance, Linux, and high-performance computational research?"
Surely what is required is to isolate the sensitive information, so that it can be protected.
That's a great idea that in practice will leak your information. The reason is that _every_ application that touches your data needs to know that it should keep your data confidential.
Broswers know to not cache data transfered over https. It knows the data was encrypted, it knows to be smart with it [for "protective" value of smart].
When you have a program that reads a file through a transparent layer of encryption, it never sees the "please-be-careful-with-this" label, and so the desktop search engine will index all the strings, the editor will write backups to . or /tmp, and so forth. All the apps think they need to do is respect what you meant by your mode bits (if you're on *nix), so it'll chmod/umask the /tmp copy the right way. If someone grabs your disk and you didn't encrypt /tmp, you lose.
And no, encrypting /tmp won't fix it: you need to know that everything the user of the data can write to is encrypted if you want to be sure. I only know one way that I can somewhat confidently say solves the problem: encrypt everything. [and then there's the network, but we'll save that for another decade ;)]
Only encrypting the sensitive data is like carrying water in bucket used for target practice: stuff will leak.
My concern with encrypting an entire disk would be fault tolerance. If a sector goes bad on a non-encrypted drive, you might lose a file. If it goes bad on an encrypted drive, do you risk losing more data or even the entire drive?
Of course, one could say that's why you make backups. But presumably the backups would also be using encryption. Therefore, they would be susceptible to the same effect. If there is a greater chance of total data loss on each device, the chance of multiple device failures leading to unrecoverable data also increases.
In the time you spent writing this post to Slashdot, you could have written a friendly letter to your IT department stating that you want some machines to not use this encryption, because these machines need maximum performance and anyway do not store any kind of personal information.
Every expression is true, for a given value of 'true'
The only protection that Full Disk Encryption gives is if someone physically gets their hands on the machine that they can not boot the machine and read its contents. This make perfect sense for laptops but makes little sense for any pertinently fixed location workstations. A laptop will physically leave the premises so it leaves itself open to theft, but a workstation (assuming you have some decent form of physical security) is much less likely to need this protection. Once a workstation is booted and the disk drive unlocked digitally then any hacker that gets a foothold on the system would then have access to it, so all that overhead of full disk encryption does no good unless the encryption is done per-user-session. When you need assess to the data you authenticate and start decrypting then, and keep it encrypted across the network. Yes, that data that you speak of should be encrypted, but you must encrypt it at the correct level to actually increase its security rather than just slowing down the machine. Anything short of that level of control and you are just fooling yourself into thinking you have protected the data. Fool-Disk-Encryption is not always the answer.
The submitter is in a research institute. Some labs in that institute have patient data, and therefore require significant security like disk encryption.
His lab works with a protozoa, and has massive computational requirements. There will never be any patient data near his lab, because the people who work with patients are in a different lab (think different department in business). They do not need disk encryption.
You say Truecrypt has "1% overhead", PGP presumably has some other "% overhead." The submitter is asking what the details of that overhead for PGP, truecrypt etc are. Whats the CPU usage, memory usage? Are disk performance penalties constant, or are they dependent on average file size, number of files, format of those files, etc etc etc. "1% overhead" may hide whopping huge performance penalties for specialist users.
I have serious doubt we even need hardware RAID anymore with current CPU speeds.
At some point in time I believed the same thing. I did a test a few years ago to see if it's still worth it to bother with hardware RAID and configured an system with linux and software RAID.
This was for a fileserver in a high performance cluster so speed mattered. I don't have the exact figures here right now, but from what I remember two years ago the software RAID solution was between 7 and 15% slower. Once you start hitting the performance limit your processes hit I/O wait and your performance goes down. When I added LVM to that back then performance got shot to hell.
Now, it's not as bad as it seems, you still get decent performance (especially considering that your setup suddenly costs a lot less and can be done on commodity hardware), and with a fair bit of tinkering with blockdev and your read-ahead buffer (provided you have enough RAM, and your usage fits that particular pattern) you can still get some very nice performance.
The reason that we went with hardware RAID in the end was because hardware RAID isn't all that expensive, and the performance gains were noticeable especially on systems that have to run 24/7 at maximum throughput.
Again, for consumer systems and services where performance isn't a primary concern software RAID is an attractive option, especially if you're on a budget.
As for overhead with encryption: it would make a nice experiment but I think 1% overhead is very optimistic especially on a busy system. The only way to be sure is to compare your performance now to the performance when you encrypt the entire disk. The only time I tested truecrypt I got a throughput of 80MByte/s, while unencrypted I got 120MByte/s, and it's been a while since I tested this. Those truecrypt tests weren't finetuned either, it was basicly a test to see if it was easy to implement.
Anything I mention here has to be taken with a grain of salt since a lot of time has passed and a lot has changed since those tests.
If policy dictates that you have to setup X, the best way to become an exception to this policy is to prove that that policy is detrimental to your project and might end up costing a lot of money. Policy doesn't care about performance, but it cares greatly about money and lost time. Do your tests, do the math, add a pricetag and talk with your manager.
The submitter is in a research institute. Some labs in that institute have patient data, and therefore require significant security like disk encryption.
Repeat after me: "The first line of security is physical."
If the servers are locked in a room with limited access (like, oh, say, 95+% of servers in the corporate world), then the probably not.
Data security is about securing the data using reasonable compensating controls. If no one can get to the disks, and those who can comprise a limited list of, say, trusted sysadmins, then it doesn't matter whether they're encrypted or not.
Requirements, if properly written, never specify implementation details -- the means. They only specify what is needed. How that is achieved is irrelevant so long as it the requirement is achieved completely.
So other than for devices that are not in access-controlled environment (like laptops or, in some cases, workstations), the need for whole disk encryption at most places is nil.
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RTFA FTW!!!
The Submitter him/herself doesn't work with sensitive info, just other dept's. IT is enforcing an overly broad solution on everyone, with considering the downside. I agree with you that sensitive data needs to be secured, but rolling out disk encryption to everyone in a company when a subset of everyone is dealing with sensitive info is maybe overkill, and the impacts to the primary activity of other depts needs to at least be quantified and considered.