Key

A surrogate primary key separates row identity from a business value that can change. A customer’s email can be corrected while orders continue referencing the same customer identifier. This is useful when the business name is mutable or wide, but stability comes from schema and application policy. A generated number is not automatically immutable, secret, globally unique, or an authorization decision. ...

An ssh-agent is a program that holds private keys for public key authentication and answers signing requests on their behalf. ssh finds it through SSH_AUTH_SOCK, the path of a Unix-domain socket, so the key is unlocked once and then borrowed by every connection that follows. The private key itself is never handed to a client. ...