The RSA Cryptosystem

1
The RSA Cryptosystem

• The methods of encryption that we have studied so
  far have been historical methods that are not
  very useful for todays computer age.
• The RSA cryptosystem, named afte its developers
  Ron Rivest, Adi Shamir, and Leonard Adelman, who
  invented the cryptosystem in 1977, is a method
  that has been widely publicized and is used
  widely today.
• The purpose of this section is to describe the
  properties of the cryptosystem and som of its
  special properties

2
RSA Cryptosystem Setup

• RSA Cryptosystem Setup
• Important Facts Concerning the RSA Cryptosystem
• Example 1 Create an RSA scheme to encipher
  USA.
• Notes Concerning Example 1

3
Security of the RSA Cryptosystem

• Security of the Method
• Example 2 Discussion on the issue of security

4
The Public Key

• When the RSA was developed, it was the first
  commercially developed type of system in which
  the sender and receiver of a message do not have
  to agree on a key beforehand in order to encipher
  and decipher messages.
• The RSA is an example of a public key
  cryptosystem.
• Anyone can send messages. Only the receiver who
  knows the value of d can decipher the message.
• Normally, a key center is responsible for
  distributing public and private keys to people
  who request them.
• This key center might be your company, school, or
  even teacher

5
ASCII Alphabet Assignment

• When enciphering messages using the RSA_Cipher
  applet (created by Mr. Fisher), we will use the
  ASCII table.
• The ASCII table allows us the flexibility to use
  letters, characters, and punctuation in our
  messages.
• Example 3 Convert Message to ASCII.
• Example 4 Lose Message Because Y gt m.