A keychain is a set of encryption rules, called keys. It authenticates applications and dynamically changes algorithms and keys during authentication. The keychain periodically changes authentication keys and algorithms to improve transmission, without interrupting services.
When two applications communicate, some unauthorized users may try to modify data packets or forge authorized users on the network, which may cause security problems. To identify modified packets and forged users, applications authenticate information by defining authentication rules. An application may use independent authentication rules.
However, an authentication rule may be cracked by unauthorized users if it is used for a long time. Modifying authentication rules by administrators is complicated and may cause faults. Besides, if each application has an independent authentication rule, many applications may use the same authentication mode, duplicating data and configuration.
Therefore, the keychain is used to manage all the authentication algorithms and keys. The keychain can control the authentication and dynamically change algorithms and key strings during authentication, which improves communication security.