The Idea:
- A cryptographic system that uses two keys -- a public
key known to everyone and a private or secret key known only
to the recipient of the message.
- When John wants to send a secure message to Jane, he uses
Jane's public key to encrypt the message. Jane then uses her
private key to decrypt it.
- Known as PGP - Pretty Good Privacy system.
- Public key cryptography was invented in 1976 by Whitfield
Diffie and Martin Hellman.
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Important:
- only the public key can be used to encrypt messages and
only the corresponding private key can be used to decrypt them.
- it is virtually impossible to deduce the private key if
you know the public key.
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Problem:
- Must know the recipient's public key to send them something
encrypted.
- Hence need some kind of public registry where people can
register their public keys...otherwise they have to send it
to you.
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