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Encryption Databases Security IT

MIT Software Allows Queries On Encrypted Databases 68

Posted by Soulskill
from the cutting-out-the-middleman dept.
Sparrowvsrevolution writes "CryptDB, a piece of database software that MIT researchers presented at the Symposium on Operating System Principles in October, allows users to send queries to an encrypted SQL database and get results without decrypting the stored information. CryptDB works by nesting data in several layers of cryptography (PDF), each of which has a different key and allows a different kind of simple operation on encrypted data. It doesn't work with every kind of calculation, and it's not the first system to offer this sort of computation on encrypted data. But it may be the only practical one. A previous crypto scheme that allowed operations on encrypted data multiplied computing time by a factor of a trillion. This one adds only 15-26%."
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MIT Software Allows Queries On Encrypted Databases

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  • Why not just encrypt the database files on HDD and memory directly? That way database can still act really fast and you can use any existing database software.
    • Re:Why? (Score:4, Informative)

      by Niobe (941496) on Monday December 19, 2011 @06:05PM (#38427448)
      Reasons I can surmise:
      1 no decryption operation required on server
      2 the data can stay encrypted in transit
      1+2 = more security than on-disk encryption
    • by Anonymous Coward

      Because you don't want to let the server ever see the decryption key.

    • by Anonymous Coward

      Because in the traditional way, the DBAs can still see the contents of the DB.

    • Re:Why? (Score:5, Informative)

      by Anonymous Coward on Monday December 19, 2011 @06:07PM (#38427474)

      Because you want to run your database in the Cloud(tm) for reliability purposes, and you don't want the provider to peek at your data.

    • Re:Why? (Score:5, Informative)

      by Rary (566291) on Monday December 19, 2011 @06:08PM (#38427492)

      Why not just encrypt the database files on HDD and memory directly? That way database can still act really fast and you can use any existing database software.

      A few key phrases from TFA: "...a trick that keeps the info safe from hackers, accidental loss and even snooping administrators ... a useful trick if you need to perform operations on health care or financial data in a situation like cloud computing, where the computer (or the IT administrator) doing the calculations can’t always be trusted to access the private numbers being crunched".

    • Re:Why? (Score:4, Informative)

      by Kaz Kylheku (1484) on Monday December 19, 2011 @06:08PM (#38427494) Homepage

      Because the database is on a remote server, and that is where the queries are executing!

      The model you're describing is that of the database running on the local machine. Data is encrypted between the database server and disk, but not encrypted in the database and not between the database and client. So the database is just a stock program running SQL queries or whatever in the usual way.

      But what if the database must be a remote server? That's how most people use databases, for the purpose of sharing data among many people, scalability, and availability.

      If the data in a database is naively encrypted, then the server cannot perform complex queries. The client must download entire tables, decrypt them, and perform the joins locally. Or so you would think.

      This is the part that these researchers seem to have attacked, from my understanding: somehow get the server to do useful queries on encrypted data without decrypting it without the monstrous overhead of the naive solutions.

      • You can, however, connect to the server via ssh tunnel and then make a database connection from there. This way the data is encrypted with remote locations too.
        • Re:Why? (Score:5, Insightful)

          by Kaz Kylheku (1484) on Monday December 19, 2011 @06:18PM (#38427592) Homepage

          Sorry, I don't see how that helps. The idea is that no program on the database server has the key to actually decrypt the data.

          The problem isn't only that you don't trust the network in between, but that you don't trust the database server admins.

          • Re:Why? (Score:4, Insightful)

            by Kjella (173770) on Monday December 19, 2011 @11:37PM (#38430062) Homepage

            Well strictly speaking, they don't need to know. The DBA - as in the person that makes sure the database is running, upgrades are done, backups are made and so on is often not really supposed to be privileged to all the information in the database. Probably the same kind of place you won't let your developers see production data, the development server has a different encryption key and the production key is set once during install, backed up in a safe and the production application server logged to hell and back including remote logging and audits. The only access anyone is supposed to have to the system is through the application that's enforcing permissions, logging and all that. I've only worked in relatively low-security environments but I'm perfectly aware that "SELECT * FROM [table]" circumvents anything and everything the application does to protect the data. In many environments that's fine and an accepted risk, if you're managing the database you should be sufficiently trusted to not go poking about. But I can easily see situations where that's not the case, without everybody jumping up and down about outsourcing. It's nothing personal in that they don't trust IT, but just like you in accounting don't want one person who can put in an invoice, approve it and take delivery you don't want one person from IT with all the keys to the castle. That this is the practical reality many places is because there hasn't been any other convenient enough way, it's not by design.

      • by Obfuscant (592200)

        This is the part that these researchers seem to have attacked, from my understanding: somehow get the server to do useful queries on encrypted data without decrypting it without the monstrous overhead of the naive solutions.

        I looked through the first few pages of the article. It is very much like how Unix passwords work. You don't decrypt the password in /etc/passwd to see if the user can log in, you encrypt his entered password with the same salt and see if there is a match. The trick is that here the DBMS is not doing the encrypting, there is a proxy that takes the performance hit, allowing the DBMS to run at full speeed.

        The text comparison (LIKE) is done by encrypting each token in the DB text and allowing a token equalit

        • by lgw (121541)

          comparison operations ( select * where salary > 60000) the encryption used maintains order. The encrypted value of 59,999 is less than the encrypted value of 60,000,

          I've never understood this bit. If, without the encryption key, I can compare two pieces of data to see which plaintext is less than then other, that seems like a huge hole. For normalized data in the DB, if some of the plaintext is known or guessable, I can probably guess all the values (since normalized values are generally represented by small integers). Heck, if I have "less than", can't I find the plaintext result of subtracting one plaintext value from another, without the key? That's effectively

          • by ChatHuant (801522)

            If, without the encryption key, I can compare two pieces of data to see which plaintext is less than then other, that seems like a huge hole.

            Read the GP a bit more carefully (more exactly, the part where it says "The encrypted value of 59,999 is less than the encrypted value of 60,000"). Both the value in the query and the contents of the database are encrypted, and the operator of the database can't read either. The operator can not compare two values without the encryption key - all he sees is an unknown query containing an unknown value, and a number of resulting records, also with unknown values.

            I'm not sure whether the query itself

            • by Obfuscant (592200)

              Both the value in the query and the contents of the database are encrypted, and the operator of the database can't read either. The operator can not compare two values without the encryption key -

              Well, if the article I read was correct, that's not true. The "operator" (DBA) certainly can read the contents of the database. When he created the database, he was told that the "salary" column contains data that needs to be compared, so it will be encrypted with an algorithm that allows comparision of values.

              He can easily extract that column and compare the values contained therein, which will sort in exactly the same manner as the cleartext.

              The only question is, can he get any significant information

          • by KazW (1136177) *

            comparison operations ( select * where salary > 60000) the encryption used maintains order. The encrypted value of 59,999 is less than the encrypted value of 60,000,

            I've never understood this bit. If, without the encryption key, I can compare two pieces of data to see which plaintext is less than then other, that seems like a huge hole. For normalized data in the DB, if some of the plaintext is known or guessable, I can probably guess all the values (since normalized values are generally represented by small integers). Heck, if I have "less than", can't I find the plaintext result of subtracting one plaintext value from another, without the key? That's effectively the same as decrypting English text.

            Incorrect. The GP was speaking about an integer comparison, not a string comparison. Integer sorting is useful for sorting data records, sorting data by the calculated result of text data wouldn't be so useful.

      • by Synerg1y (2169962)

        None of this matters because...

        A. guy (OP) at the very top of this chain doesn't have a clue wtf he's talking about

        I guess the scenario they're talking about is a machine they can't trust NOT to be compromised, thus loading plaintext in memory (how currently on the fly works), that's a client to database interaction. Decrypting the data nowadays works just fine, no idea here either, old hardware perhaps? They're talking about accessing the data w/o ever decrypting it, thus there is nothing to steal at any

        • by Obfuscant (592200)

          how would this do anything to an admin's ability to access the database?

          It wouldn't. The admin would have the permissions to do a "select * from ..." query. It would, however, present him with only encrypted data as a result. The decryption of the data itself takes place only on the client (or proxy), which we assume is outside his scope of control.

          Now, that does raise the question of leaks from the "comparision" columns. That is, those that are encrypted with an algorithm that always returns the same ciphertext and the ciphertext has the same ordering properties as the clea

    • by zill (1690130)
      Even if every row is individually encrypted the number of rows and the table layouts can still be leaked. Also by encrypting each row you've basically disabled all the relational operations.

      If you meant encrypting the entire database with one key then when the database is compromised all your data is compromised. With CryptDB only the data of currently logged-in users are compromised.
    • by gman003 (1693318)

      It's for The Cloud. It lets you have the database hosted by people you don't fully trust, without compromising security.

      • We still have to trust the person we gave a password to, so that they can access the plaintext information in the first place, and as you probably know, they are the worst with securing passwords and are probably using computers that are not secure (not up-to-date, has malware/virus on their machine). =(

        Plus you now have to (in some cases) re-write your tables to make up for the limitations of CryptDB: they referred to storing dates as separate fields quite a few times in their PDF(if comparing dates is imp

        • by gman003 (1693318)

          We still have to trust the person we gave a password to, so that they can access the plaintext information in the first place

          The point of it is that you have the passwords, and all "The Cloud" has is the theoretically-useless-and-indistinguishable-from-garbage ciphertext. You can tell The Cloud to perform certain operations and retrieve the data, but there's (theoretically) no way for the Cloud to know what, exactly, they have.

  • by Trepidity (597) <delirium-slashdo ... org minus author> on Monday December 19, 2011 @06:07PM (#38427468)

    This is not really the first practical such system, nor have all previous systems been a trillion times slower. As seems to be a pattern with MIT press releases, the press release makes exaggerated claims, but the paper itself is actually quite good and gives proper credit where it's due, discussing a number of previous systems that implement related functionality, and some existing algorithms from the literature that they borrow and implement directly in CryptDB.

    • A trillion maybe not, but certainly much, much, much, much slower than an unencrypted calculation. If you factor in cache effects, CPU stalls, the need to do a shitload of work just to unencrypt each value before using it, then performing a simple arithmetic mean over the encrypted rows of a database table could easily add up to hundreds of thousands of wasted cycles per item, compared with doing the same calculation on an unencrypted chunk of memory.

      There's just no question about it. It's going to be dog

      • the need to do a shitload of work just to unencrypt each value before using it

        I think the point of the system is that you don't need to unencrypt the values at all to perform the calculations. It's homomorphic encryption [wikipedia.org].

        • Re: (Score:1, Funny)

          by Anonymous Coward

          I can't see any Christian data center allowing this homo-encryption. Hate the sin, love the sinner, blah blah blah.
          Now we see what Alan Turing was really up to when he invented the computer!

        • Sure, but you can never fully support the 4 arithmetic operations homomorphically, as then your encryption map would be an isomorphism, ie the "encryption" would be trivial to break.

          So something must always give, at best you might have a system where some operations work for some set of numbers, but will not work for all numbers. If you don't know anything about what the encrypted dataset contains, you won't be able to know for certain if your homomorphic calculation is even correct. And if you restrict t

    • by Anonymous Coward on Monday December 19, 2011 @06:36PM (#38427770)
      It's a fundamental tension between the scientists and the PR departments. I see this where I work (at a DoE national lab). Basically, we scientists publish cool results, and submit them to the PR department as candidates for press releases. The PR department of course tries to jazz it up as much as they can. So we go back-and-forth with them for a bit, trying to compromise on something is isn't factually wrong while still being accessible to the general public, and giving people a good feel for why our work is important.

      Then the press release is interpreted by media outlets, which dumb it down even more and stretch the claims even further. After even just 2 or three levels of this, honest sensible papers turn into grandiose hyperbole. A nice theoretical result on metamaterials becomes "scientists invent invisibility cloak"; work on new semiconductors becomes "world's fastest transistor"; and a paper on tentative correlations between X and Y becomes "X causes Y!" Believe me when I say that most scientists are embarrassed when they see their results exaggerated and misinterpreted like this.

      This is not meant to excuse such behavior. Some PR departments are better than others. At some institutes there is too much pressure from on-high to be seen in the media as being innovative, revolutionary, and all that other buzzwords. But at the end of the day, scientists have to have the courage (and the authority) to prevent press releases from going out that are so stretched as to be factually incorrect.
      • Mod parent up

      • by Trepidity (597)

        Yeah, I agree on the last point, though pragmatically I made somewhat of a distinction between tenured and untenured faculty. If you're untenured at a place like MIT, there's huge pressure to get publicity and do Earthshattering Research, so I can cut overhyping some slack. I hold tenured faculty to a higher standard, though, because they don't have to overhype their research to keep their job. Looks like in this case one of the faculty co-authors is untenured, so maybe should get some slack on account of h

    • It seems typical of most universities' press releases. They have PR divisions which troll the research faculty for new developments they can turn into whiz-bang popularized "articles."

      I think that it's sort of the paradigm for how things are done at most large institutions: the researchers can't be bothered or don't have time to write popular accounts, do extraneous paperwork or file patents, so others are made to do it for them. The result is extraordinary claims in the press releases at best, and ser

  • by vlm (69642) on Monday December 19, 2011 @06:28PM (#38427686)

    Order Preserving Encryption, how is it implemented? The paper page 4, simply lists that it exists and has a pointer to an article somewhere that I have no access.

    I'm not understanding how this hides "known plaintext" attacks. Perhaps its not intended to. Like I said, I have no access to the footnoted OPE article. So, lets say you got a medical database of private health care info, where the diagnosis is a column. If you can sort it, all the folks with "aids" sort at the top, right above the "alcoholism" diagnosis, with the "worms, intestinal" and I suppose the "zoophilia" people at the bottom.

    I suppose, the solution, is unless there is a business need to sort by diagnosis, you don't use OPE for that column, you use DET or if no need for "group by", then RND.

    • by Tacvek (948259)

      The scheme they use is reference 4, which is available online at http://www.cc.gatech.edu/~aboldyre/papers/bclo.pdf [gatech.edu] (found with simple Google search for the paper's title: Order-Preserving Symmetric Encryption)

      My bigger issue is with a chosen plain-text attack. If a column is currently stored in say DET, and you have full view of the database, and you arrange for say an insertion of a row with some specific value, now you know all the rows with that value. Even if you can only arrange for a "select * from d

      • by Anonymous Coward
        I recall an enterprise database system which (used to, not sure if it still does) allowed you to do an "explain" of a SQL query against a view even though you had no access rights to the underlying tables. The "explain" output showed estimated row counts of intermediate results even though some of those results would have been eliminated because the view limited your access (such as by checking your role in the organization and only letting you see your region's sales numbers). As the statistics got better,
      • by Fnord666 (889225)

        My bigger issue is with a chosen plain-text attack. If a column is currently stored in say DET, and you have full view of the database...

        If I understand correctly, one of the functions of the layering of crypto is to prevent an attacker from having a full view of the database. DET would be layered below an RND outer layer, preventing you from gaining that view.

        • by Tacvek (948259)

          The design is that once any legitimate query needs access to the DET layer, the proxy has the database replace the whole column with the one with RND stripped off, leaving just DET. They mention that it would be possible to re-encrypt back to DET if after a long enough period of time if no further queries occurred that needed it.

          It would completely kill performance if they always restored the RND layer, since much of the overhead of the system comes from pulling and decrypting columns, so that operation mus

  • by Anonymous Coward

    Performing searches -- and other operations -- on encrypted data has some big potential to help protect our privacy in an age where people are losing control of their personal information. Since the data is *never* decrypted by the server, no information will be leaked even if the communication channel between the client and the server is compromised, or the server itself is hacked. If the query is also encrypted before sending, which is the case for most schemes, the server does not learn anything about th

  • so, basically... (Score:2, Flamebait)

    by mtrachtenberg (67780)

    "A previous crypto scheme that allowed operations on encrypted data multiplied computing time by a factor of a trillion. This one adds only 15-26%."

    So, basically you're saying that both schemes slow things down, right?
      --PHB

    • by Thiez (1281866)

      Yes. What is your point?

      • by bytesex (112972)

        It's probably that the website with pictures of his dog backed by mysql is blazing fast and doesn't need this, and that therefore he thinks that *nobody* will need this.

  • Have to try it out first though, but this is one of the hardest security problems to solve: How do you trust others to maintain the servers your database is on. Even if there are attacks against this, it seriously raises the bar for attackers. Especially if your attacker only has access to your database for a brief period of time. I can see attacks against this if your adversary can analyze you queries over a long period of time.

APL is a write-only language. I can write programs in APL, but I can't read any of them. -- Roy Keir

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