Encryption
Encryption is the process of obscuring
information to make it unreadable
without special knowledge.
http://en.wikipedia.org/wiki/Encryption
Copyright © 2008 by Helene G. Kershner
Encryption is only a part!
To ensure secrecy of a message one needs
to be sure :
 the communication is secure
 it is received by the right “people”
 it can be decrypted (or decipher)
 In other words, we must verify the integrity
and authenticity of a message.

http://en.wikipedia.org/wiki/Encryption
Copyright © 2008 by Helene G. Kershner
Encryption
Great Idea: A cipher is an algorithm for
performing encryption (and the reverse,
decryption) — a series of well-defined
steps that can be followed as a procedure.
 a cipher is a process
 it is more than a secret code
 WWII – COLOSSUS, Code Talkers
Copyright © 2008 by Helene G. Kershner
Encryption
The Government’s Need to Know
Vs
The Right to Privacy
Which should have higher priority?
Copyright © 2008 by Helene G. Kershner
Encryption
Is this just a government vs the people
type of issue?
Why would ordinary citizens be
interested in encrypting information?
Copyright © 2008 by Helene G. Kershner
Encryption
While encryption has been used to protect
communications for centuries, until recently
only organizations and individuals with an
extraordinary need for secrecy have made
use of it.
 This changed in the 1970s

http://en.wikipedia.org/wiki/Encryption
Copyright © 2008 by Helene G. Kershner
Encryption
In the mid-1970s, strong encryption
emerged from government agencies and
moved into the public domain.
 WHY?

Copyright © 2008 by Helene G. Kershner
Encryption
Where is it used if not by the government?
 Encryption is now widely-used in computer
systems such as
 Internet e-commerce,
 mobile telephone networks and
 automatic teller machines.

http://en.wikipedia.org/wiki/Encryption
Copyright © 2008 by Helene G. Kershner