Who are Alice and Bob and what does this have to do with Cryptography? Excellent Question!
Obviously not the persons in the above picture. Alice and Bob are ficticious characters that represent
Private and Public key encryption. The public key is known to everyone
and the private key is only known by the receiver.
For example, Alice wants to send Bob a secure message. Alice uses Bob's public key to send (encrypt)
the message, and then Bob uses his private key to read (decrypt) the secure message.
The public key is irreversible, a one way function. The public key does not enable a person to decrypt
the secure message.
Public key cryptography was created in 1976 by Whitfield Diffie and Martin Hellman. It is also
called asymmetric encryption because it uses two keys instead of one key (symmetric encryption).
The most facinating part of this is the RSA. The RSA was developed in 1977 by Ron Rivest, Adi Shamir, and Leonard Adleman.
RSA uses an algorithm and is used mostly for encryption on the Internet.
How RSA Works
It involves multiplying two large prime numbers and through
additional operations deriving a set of two numbers that constitutes the public key and
another set that is the private key. Both the public and the private keys are needed to
encrypt and decrypt, but as stated above, only the owner of a private key
ever needs to know it.
It is virtually impossible to deduce the private key if you know the public key.
Information for this page was obtained from The Code Book; Anchor Books; 1999 by Simon Singh and
from searchSecurity.com
