History is a funny thing. It’s amazing that what many children see in early schooling as a boring collection of facts is neither boring nor factual. On a good day we might get some dates correct, but there isn’t a “fact” in history that isn’t open to interpretation. This is as it should be; think about all the factors that went into a major life decision- say a marriage or picking your college. Now distill everything involved in that decision into a paragraph, stick it in a drawer for a couple decades, pull it out, and see if it still matches your memories and accurately reflects the situation. If you don’t have a few decades to spare, the answer is, “it doesn’t.”

The main problems with history are actually those we see in computer science- bandwidth, compression, indexing, and search. We can’t possibly collect and store all the bandwidth of human interaction, so we drop into “sampling mode” and further compress it for long-term storage. We then rely on imperfect indexing to organize the data, and flawed search protocols to find what we need. We don’t collect everything, lose large amounts of data in compression, poorly index it, and rely on primitive search tools. No wonder history is open to interpretation.

Take the Maginot Line. And Encryption.

For those of you who aren’t military history buffs, the Maginot Line was a series of interlocking defenses, sometimes 25 kilometers deep, that the French built after WWI to keep the Germans out. In popular security culture the term is often used as an analogy to describe a misguided investment designed to fight the last war that’s easily circumvented. In marketing films of the time the Maginot Line was promoted as being an invincible defense for France. A folly painfully realized when the German invasion succeeded in only a month. A metaphor for a failure of hubris.

Reality is, of course, open to interpretation.

Another interpretation of the Maginot Line is that it completely succeeded in its defined task, preventing a frontal assault along the Franco-German border. The Maginot Line held, but the other defensive layers- the Ardennes and the French Army along the Belgian border- failed.

The Maginot Line was designed for a mission it effectively met, but other design flaws in the defense in depth of France lead to the German occupation.

Which brings us to encryption.

The first version of the PCI Data Security Standard called encryption, “the ultimate data security technology”.


Encryption is a powerful technology, but probably the most-misunderstood in the context of what it provides for data security. With the McAfee acquisition of SafeBoot for $350M, encryption is in the headlines again. A while ago I wrote the Three Laws of Data Encryption to help users get the most value out of encryption.

I really do think of encryption as the Maginot Line of data security. It’s powerful, nigh invincible, if used correctly, but easily circumvented if your other security controls aren’t properly designed. For example, if you have a large application connected to a large database full of encrypted credit card numbers, and that application is subject to SQL injection, odds are your encryption is worthless. Laptop encryption protects you from stolen laptops, but is useless against malicious software running in the context of the user.

As I keep walking through the Data Security Lifecycle you’ll see a lot of posts on encryption; it’s a fundamental technology for protecting content. But when big companies start throwing around hundreds of millions of dollars I think it’s an opportune time to step back and remind ourselves of the problem we’re trying to solve, and how the different parts of the solution fit together.

If we want a real-world example we need to look no further than TJX. Rumor has it that cardholder data was encrypted, but the attackers sniffed an unencrypted portion of the communications to perform transactions. The encryption worked perfectly, but the breach still succeeded.