B: Why?
KXA: If it works,
and you tell someone about being here,
it could be important to be able to prove that you really wrote this.
B: You're right.
But I don't feel comfortable with putting my key on a computer which isn't mine.
KXA: Just remove the key after use.
B: Ok.
KXA: And you don't have to use an SMS, actually.
Could be infrared as well.