Encryption works by using algorithms and keys to secure digital information during transmission. Symmetric-key encryption uses the same secret key between two computers, while public-key encryption uses separate public and private keys. A popular implementation of public-key encryption is Secure Sockets Layer (SSL) and its successor Transport Layer Security (TLS), which allow for secure transmission of sensitive information on the internet through the use of encryption during online transactions.

1. How Encryption Works

2. Introduction to How Encryption Works
A typical transaction might include not only our
names, e-mail addresses and physical address and
phone number, but also passwords and personal
identification numbers (PINs).
E-commerce relies on
the ability to send information
securely -- encryption tries to
make that possible.
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pictures.
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3. Security Encryption Systems
Computer encryption is based on the science of
cryptography, which has been used as long as humans
have wanted to keep information secret. Before the digital
age, the biggest users of cryptography were
governments, particularly for military purposes.
Here's an example of 1 2 3 4 5
a typical cipher, with a grid of 1 A B C D E
letters and their 2 F G H I J
corresponding numbers: 3 K L M N Q
4 O R S T U
5 V W X Y Z

4. Symmetric Key
In symmetric-key encryption, each computer has a secret
key (code) that it can use to encrypt a packet of information
before it is sent over the network to another computer.
Symmetric-key requires that you know which computers will be
talking to each other so you can install the key on each one.
Symmetric-key encryption is essentially the same as a secret
code that each of the two computers must know in order to
decode the information. The code provides the key to decoding
the message.

5. Public Key Encryption
In November 1976, a paper published in the journal IEEE
Transactions on Information Theory, titled "New Directions in
Cryptography," addressed this problem and offered up a
solution: public-key encryption.
Also known as asymmetric-key encryption, public-key
encryption uses two different keys at once -- a combination of a
private key and a public key.

6. SSL and TLS
A popular implementation of public-key encryption is
the Secure Sockets Layer (SSL). Originally developed by
Netscape, SSL is an Internet security protocol used by Internet
browsers and Web servers to transmit sensitive information.
SSL has become part of an overall security protocol known as
Transport Layer Security (TLS).
Look for the "s" after "http"
in the address whenever
you are about to enter
sensitive information, such
as a credit-card number,
into a form on a Web site.