Symmetric cryptography refers to a type of cryptography where the key that is used to encrypt the data is the same one that is used for decrypting the data. Thus, it is also known as shared key cryptography. The key must be established or agreed upon before the data exchange occurs between the communicating parties. This is the reason it is also called secret key cryptography.
There are two types of symmetric ciphers: stream ciphers and block ciphers. Data Encryption Standard (DES) and Advanced Encryption Standard (AES) are typical examples of block ciphers, whereas RC4 and A5 are commonly used stream ciphers.
