Encryption, a sub-set of cryptography, is the process of encoding data so that it is accessible only to authorized parties. Modern computer users enjoy the benefits of encryption in many different forms including encrypted browsing connections (via SSL) while accessing financial data or submitting credit card payments, the ability to encrypt entire hard disks with modern operating systems and tools (such as BitLocker in Windows 7), and email/message encryption (via tools like Pretty Good Privacy).
There are two primary types of encryption, symmetric-key and public-key. Symmetric key is the oldest type of encryption and uses both the same algorithm for encrypting and decrypting the message. A simple shift-cipher (wherein you, say, shift all the letters in the alphabet over one space to create a code) is an example of a symmetric key encryption technique. The key you use to encrypt the message is the key the recipient uses to decrypt it. This form of encryption is inherently weak as both parties (or machines) need to know the secret key to use it.
Symmetric-key encryption has been replaced by public-key (or asymmetric-key) encryption. With public-key encryption one key is used for encrypting and, thanks to complex mathematical algorithms, another key (the privately held key) is used for decryption. Thus with a public-private key system a message can be encrypted by a third party using the public key that only the individual with the private key can decrypt. This method forms the basis of many modern encryption techniques including the Diffie-Hellman method and RSA encryption.
For more information on encryption, including how to use it to secure your data, check out the following How-To Geek articles:
- HTG Explains: What is Encryption and How Does It Work?
- The How-To Geek Guide to Getting Started with TrueCrypt
- How To Anonymize and Encrypt Your BitTorrent Traffic
- The Top 10 Tips for Securing Your Data
- By Jason Fitzpatrick on 01/25/13