Encryption is an essential tool for protecting data—but the technology can be a bit confusing. This ebook explains what encryption is, how it works, and why it’s so important.

From the ebook:

Encryption is far more than just scrambling an email to protect it from prying eyes—it’s a practice that goes back well into the analog days. In essence, anything that is encoded using an algorithm is encrypted.

Most everyone has experience with simple encryption, like substitution ciphers that alter the letters of the alphabet using a particular rule, like A=Z, B=Y, C=X, and so on.

Even a simple cipher like mixing up the letters of the alphabet presents an enormous number of potential solutions because of the factorial nature of encryption. Take the English alphabet, for example. It has 26 letters, which means there are 26 factorial ways to mix it up. Mathematically that means 26 x 25 x 24 x 23 x 22 x 21… x 1 possibilities.

26 factorial, or 26!, means a simple substitution cipher of the English alphabet has 403,291,461,126,605,700,000,000,000 possible solutions. Ideally this would mean an English substitution cipher would be difficult to solve, but it isn’t, really. All a good cryptanalyst needs to do is look for recurring characters to start making educated guesses to solve the cipher quickly.

The minds behind modern encryption know how easy solving simple ciphers can be, especially given the raw power of modern computers—if a human can crack it with any degree of speed a computer can probably do it faster.

To prevent cracking, modern encryption has to be more complicated, use more tricks to scramble data, and make it (practically) computationally impossible for an attacker to break the encryption.