Principles of Public Key Cryptography
Public Key Cryptography uses a method of encoding and decoding that employs a special case of the one-way function known as a trapdoor or one-way function. A function f(x) is considered to be a one-way function if it is easy to compute the function f(x) = y for any input x. But the opposite that is computing x from f(x) is significantly more complicated unless some piece of information is known.
The process of using public key cryptography is relatively straightforward. To send a message, the sender (Alice) obtains a copy of Bob’s (recipient) public key, either by email or from a key chain server that stores a large number of public keys. The resulting encrypted message is then sent to Bob who uses their shared private key to restore the original message.