Security Key

In cryptography, a security or secret key is used for encrypting and decrypting content (see encryption). Depending on whether the encryption method is symmetric or asymmetric, a security key has different functions.

• Symmetric encryption: In a symmetric encryption scheme, where both the sender and receiver use the same key, the security key both encrypts and decrypts the content that is to be secured. So if Alice wants to send private information to Bob, she encrypts it using the security key. Then Bob can decipher it using the same security key.

• Asymmetric encryption: In asymmetric encryption, each user has both a public key which is known by everybody and a private key known only to the holder. If Alice encrypts a message using Bob's public key, only Bob can decrypt it with his private key, and vice versa.

Encrypting and decrypting content is a very complex activity, performed by specialized software. Some applications even self-compute and agree upon keys without user intervention. One example of this is the HTTPS protocol used to send information securely over the Internet. When you perform an online transaction with a bank or ecommerce site, security keys are exchanged without you having to do anything.