Symmetric Encryption

Encryption is the process of disguising information to make it unreadable by those who lack the tools to decipher it. In symmetric encryption, the tool you need is called a key, which is a secret number or text, like a password, that is known only to the person using it. In symmetric encryption, the same key is used to encrypt and decrypt messages. This differs from asymmetric (or public-key) encryption, which uses one key to encrypt messages and a different one to decrypt messages.

Symmetric encryption is much faster than asymmetric encryption, but it has some disadvantages. It is hard to make sure that messages encrypted with symmetric encryption came from the correct person and were not altered on the way. Symmetric encryption also requires both parties to share a secret key, but it is hard to choose, distribute and store keys without error and loss. As a result, most current security systems use asymmetric encryption to distribute keys securely. Once that is done, symmetric encryption takes over.

Symmetric encryption is also sometimes called single-key and private-key encryption. Private-key encryption should not be confused with the ‘private key’ used in public-key encryption. Some common examples of symmetric encryption are the Advanced Encryption Standard (AES), RC4, Blowfish, and IDEA (International Data Encryption Algorithm).