Symmetric and Asymmetric key-based algorithms

Symmetric key-based algorithms use a single secret key for both encryption and decryption. To use a symmetric encryption scheme, the sender and receiver must share a key in advance. Because symmetric encryption is less computationally intensive and requires less bandwidth, it is common to exchange a key using a key-exchange algorithm and transmit data using an enciphering scheme.

Figure 3. Key-based Symmetric algorithm

Asymmetric key-based algorithm uses two keys - the key used to encrypt a message differs from the key used to decrypt it. In this, a user has a pair of cryptographic keys — a public key and a private key. The private key is kept secret, while the public key may be widely distributed. Messages are encrypted with the recipient's public key and can only be decrypted with the corresponding private key. The keys are related mathematically, but the private key cannot be feasibly (i.e., in actual or projected practice) derived from the public key.

Figure 4. Key-based asymmetric algorithm