First of all we will define what is symmetric and what asymmetric encryption.

Symmetric Encryption is when a single key is being used for encrypting and decrypting text.  It is fast and is used for large data transmission. So you have to remember:

• one key
• fast
• large data

Asymmetric Encryption is when we use different keys for encrypting and decrypting text. It is slow and is used for encrypting keys. So you have to remember:

• pair of keys
• slow
• small data

So imagine a situation in which you have to encrypt your data transfer. You can use both techniques for better results. So you can do the following:

• Server uses symmetric encryption to encrypt the response that goes back to client – encrypt data with random symmetric key
• Server encrypts with asymmetric encryption with the users public key the servers symmetric key – encrypt server’s symmetric key with user public key
• Server sends back the data to client together with the encrypted key
• User decrypts the encrypted symmetric key with his private key – decrypt server’s symmetric key with his private key
• User decrypts the encrypted data with the decrypted symmetric key – decrypt data with decrypted symmetric key