How Encryption Works
The encryption process involves taking each character of data and comparing it against a key. For example, you could encrypt the following string of data in any number of ways:
The quick brown fox
For sample purposes, let’s use a simple letter-number method. In this method, each letter in the alphabet corresponds to a particular number. (You may have used this method as a kid when you got a decoder wheel in your Cracker Jack or breakfast cereal box.) If you use a straight alphabetic-to-number encryption (for example, A=1, B=2, C=3, and so on), the data translates into the following:
20 8 5 17 21 9 3 11 2 18 15 23 14 6 15 24
You can then transmit this series of numbers over a network, and the receiver can decrypt the
string using the same key in reverse. From left to right, the number 20 translates to the letter T, 8 to H, 5 to E, and so on. Eventually, the receiver gets the entire message:
The quick brown fox
Most encryption methods use much more complex formulas and methods. Our sample key was about 8 bits long; some keys are extremely complex and can be a maximum of 128 bits long. The larger the key (in bits), the more complex the encryption—and the more difficult it is to crack.
To encode a message and decode an encrypted message, you need the proper encryption key or
keys. The encryption key is the table or formula that defines which character in the data trans-
lates to which encoded character. Encryption keys fall into two categories: public and private.
Let’s look at how these two types of encryption keys are used.
Private Key Encryption
Private keys are known as symmetrical keys. In private key encryption technology, both the
sender and receiver have the same key and use it to encrypt and decrypt all messages. This makes it difficult to initiate communication the first time. How do you securely transmit the single key to each user? You use public keys, which we’ll discuss shortly.