Editing Public-key cryptography (section)

== Hybrid cryptosystems ==
Because asymmetric key algorithms are nearly always much more computationally intensive than symmetric ones, it is common to use a public/private ''asymmetric'' [[key-exchange algorithm]] to encrypt and exchange a ''symmetric key'', which is then used by  [[symmetric-key cryptography]] to transmit data using the now-shared ''symmetric key'' for a symmetric key encryption algorithm. [[Pretty Good Privacy|PGP]], [[SSH]], and the [[SSL/TLS]] family of schemes use this procedure;  they are thus called ''[[hybrid cryptosystem]]s''. The initial ''asymmetric'' cryptography-based key exchange to share a server-generated ''symmetric'' key from the server to client has the advantage of not requiring that a symmetric key be pre-shared manually, such as on printed paper or discs transported by a courier, while providing the higher data throughput of symmetric key cryptography over asymmetric key cryptography for the remainder of the shared connection.