"In contrast to the cooperative preparations required for
setting up private key encryption, such as secret-sharing and close
coordination between sender and receiver, you can act entirely on
your own to create and publish two numbers that enable anyone,
using the RSA encryption formula, to send a private message to you
through a public channel. The message becomes 'First Class' e-mail,
so to speak, as if sealed in an envelope. Using the two numbers you
have published, anyone can scramble a message and send it to you.
You are the only one who can unscramble it--not even the sender of
the message can decrypt the ciphertext..."