Introduction Cryptographic attacks, even more advanced ones, are often made more difficult to understand than they need to be. Sometimes it’s because the explanation is “too much too soon” — it skips the simple general idea and goes straight to real world attacks with all their messy details. Other times it’s because of too much formalism: it’s this and that, without any regard for where these came from or what they signify.
The line between a “classic” and a “modern” cryptographic attack can be blurred. However, most people would agree that (for example) differential cryptanalysis is not like a basic frequency analysis. The mathematics involved is more complicated, the era of cryptography that gave rise to the attack is more rugged and mature, and it’s much harder to explain the attack to a seventh-grader and have them exclaim “I could have thought of that”.
Regardless, even these attacks can be perfectly easy to understand, once they are explained plainly. In this write-up, we lay out in simple terms: For more attacks and more explanations see our earlier report . Classic-Flavor Cryptanalysis Meet-in-the-Middle Attack DES, designed by IBM, can be considered to be the cipher that kicked off the modern era of cryptography.
We’ll mention DES a few more times below (and if you are really curious, is an excellent read), but one of its properties was that its key-length was nerfed post-design to a mere 56 bits, due to — as Schneier puts it in the abo.