http://en.wikipedia.org/wiki/Public-key_cryptography http://en.wikipedia.org/wiki/Public-key_cryptography The sender and receiver exchange public keys which ca

http://en.wikipedia.org/wiki/Public-key_cryptography http://en.wikipedia.org/wiki/Public-key_cryptography The sender and receiver exchange public keys which can be visible by anyone. Only the private key can unlock what is locked with its associated public key. It would be like me sending you a locked box (that only I have the key to) with a slot in the top to allow messages to go in but not come out. And then you send me a similar locked box with a slot in it for me to put messages in. Once a message goes in the slot, only the private key owner can unlock it. There is still a problem with man in the middle attacks where an attacker steals each public key and sends his own public key back to both participants. This problem is somewhat solved by the use of certificate authorities who certify that the public keys belong to who they say they belong to. Some of these certificate authorities have delegated their powers to organizations which may not be trusted.