Wikipedia defines encryption as “the process of obscuring information to make it unreadable without special knowledge, sometimes referred to as scrambling.”� When businesses send or receive sensitive information such as social security numbers, credit card information, or confidential business data; they use encryption to ensure that unauthorized people do not get their hands on it. The sensitive information is encrypted, or put into a special code, so that only those you want can access it.

So how does encryption work? First we must distinguish between the two types of computer encryption, symmetric and public key. Let’s take a look at these two systems in detail.

Symmetric-key encryption works much like old-fashioned codes do. Suppose you and I make a code that shifts each letter one down, so that A matches with B, B with C, C with D, etc. When I send you, “IFMMP,”� you know that I mean, “HELLO.”� But anyone else seeing the message will be unable to decipher it unless he or she knows the code we are using. Similarly, in symmetric-key encryption, each computer has a secret code that it uses to encrypt information before sending it to another computer over the network. Each computer involved must know the code in order to decode the information, so it is necessary to know who is talking to whom.

Public-key encryption involves using both a private key and a public key. Your private key is known only by your computer, while your computer gives its public key to any other computer that wants to have a secure communication with it. Public-key encryption involves the following steps:

• First, the message must be encrypted using the private key (no one knows about this code);
• Then, the symmetric key code itself must be encrypted using the public key of the computer receiving the message.
• The receiving computer gets both the message and the encrypted code. It first decodes the encrypted code using its public key. So now it has the symmetric key code and can use this key code to decipher the original message being sent.

As you can see, public-key encryption requires a lot of computing, so systems usually use a combination of public and symmetric encryption. Computers may interact initially using the public-key encryption method, but then continue their communication using symmetric-key encryption to save time and effort in computing.

Most systems use hashing algorithms to come up with the encryption. For example, an extremely simplified version of this would be something like: “Take the input number and multiply it by 770.”� So if the inputted value is 45,064, the hash value would be 34,699,280, or 45,064 x 770. Seeing just the hash value, it is extremely hard to know that it was obtained by multiplying 45,064 and 770. But when the computer knows the key (multiply by 770), it is easy to know that for 34,699,280 the input must have been 45,064.

In reality, algorithms are much more complex and use very very large hash values for encryption, such as 40-bit and 128-bit numbers. This means that there are billions (3,402,823,669,209,384,634,633,746,074,300,000,000,000,000,000,000,000,
000,000,000,000,000 in the case of 128-bit) of possible different combinations! That is why it is so hard to decipher the code!