(Continuing the '

real-world' application of this)

Assuming

Eve only wants to steal '

useful' items, or assuming you can

generate an

infinite number of

padlocks (which you can on a

computer), you could just let

Bob send

Alice his

unlocked padlock, then

Alice locks the

medicine in the

chest. Of course, this has the slight problem, where Alice could

swap the

padlock for one of her own.

In the real world, that basically means, you can give everyone a copy of your

RSA public key (padlock), because it's only useful for

encrypting (locking) things, you need the

private key (the key) to

decrypt (unlock) it --

**however** you need to be sure you have the

**correct** padlock, lest you be tricked into encrypting something to some

evil third party.