$1.$ In a scenario where Nancy and Matthew are using public key encryption, which keys will Nancy have the ability to see in her public keyring $(--$list$-$keys$)?$

$2.$ In a scenario where Nancy and Matthew are using public key encryption, which keys will Matthew have the ability to see in his public keyring $(--$list$-$keys$)?$

$3.$ If Nancy wishes to send a message to Matthew, which key does she use to encrypt the message?

$4.$ If Matthew receives an encrypted message from Nancy, which key does he use to read it$?$

$5.$ If Matthew wishes to send a message to Nancy, which key does he use to encrypt the message?

$6.$ If Nancy receives an encrypted message from Matthew, which key does she use to read it$?$

$7.$ What is a keyring?

$8.$ Which commands are used to display all the keys in a user$$s keyring?