NordVPN Promotion

Home / Blogs

The Uses and Abuses of Cryptography

Another day, another data breach, and another round of calls for companies to encrypt their databases. Cryptography is a powerful tool, but in cases like this one it’s not going to help. If your OS is secure, you don’t need the crypto; if it’s not, the crypto won’t protect your data.

In a case like the Anthem breach, the really sensitive databases are always in use. This means that they’re effectively decrypted: the database management systems (DBMS) are operating on cleartext, which means that the decryption key is present in RAM somewhere. It may be in the OS, it may be in the DBMS, or it may even be in the application itself (though that’s less likely if a large relational database is in use, which it probably is). What’s to stop an attacker from obtaining that key, or perhaps from just making database queries?

The answer, in theory, is other forms of access control. Perhaps the DBMS requires authentication, or operating system permissions will prevent the attacker from getting at the keys. Unfortunately—and as these many databreaches show—these defenses are not configured properly or aren’t doing the job. If that’s the case, though, adding encryption isn’t going to help; the attacker will just go around the crypto. There’s a very simple rule of thumb here: Encryption is most useful when OS protections cannot work.

What do I mean by that? The most obvious situation is where the attacker has physical access to the device. Laptop disks should always be encrypted; ditto flash drives, backup media, etc. Using full disk encryption on your servers’ drives isn’t a bad idea, since it protects your data when you discard the media, but you then have to worry about where the key comes from if the server crashes and reboots.

Cloud storage is a good place for encryption, since you don’t control the machine room and you don’t control the hypervisor. Again, your own operating system isn’t blocking a line of attack. (Note: I’m not saying that the cloud is a bad idea; if nothing else, most cloud sysadmins are better at securing their systems than are folks at average small companies.) Email is another good use for encryption, unless you control your own mail servers. Why? Because the data is yours, but you’re storing it on someone else’s computer.

Encryption is a useful tool (and a fun research area), but like all tools it’s only useful if properly employed. If used in inappropriate situations, it won’t provide protection and will create operational headaches and perhaps data loss from mismanaged keys.

Protecting large databases like Anthem’s is a challenge. We need better software security, and we need better structural tools to isolate the really sensitive data from average, poorly protected machines. There may even be a role for encryption, but simply encrypting the social security numbers isn’t going to do much.

NORDVPN DISCOUNT - CircleID x NordVPN
Get NordVPN  [74% +3 extra months, from $2.99/month]
By Steven Bellovin, Professor of Computer Science at Columbia University

Bellovin is the co-author of Firewalls and Internet Security: Repelling the Wily Hacker, and holds several patents on cryptographic and network protocols. He has served on many National Research Council study committees, including those on information systems trustworthiness, the privacy implications of authentication technologies, and cybersecurity research needs.

Visit Page

Filed Under

Comments

Comment Title:

  Notify me of follow-up comments

We encourage you to post comments and engage in discussions that advance this post through relevant opinion, anecdotes, links and data. If you see a comment that you believe is irrelevant or inappropriate, you can report it using the link at the end of each comment. Views expressed in the comments do not represent those of CircleID. For more information on our comment policy, see Codes of Conduct.

CircleID Newsletter The Weekly Wrap

More and more professionals are choosing to publish critical posts on CircleID from all corners of the Internet industry. If you find it hard to keep up daily, consider subscribing to our weekly digest. We will provide you a convenient summary report once a week sent directly to your inbox. It's a quick and easy read.

Related

Topics

IPv4 Markets

Sponsored byIPv4.Global

Cybersecurity

Sponsored byVerisign

Domain Names

Sponsored byVerisign

DNS

Sponsored byDNIB.com

Brand Protection

Sponsored byCSC

New TLDs

Sponsored byRadix

Threat Intelligence

Sponsored byWhoisXML API

NordVPN Promotion