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Terminology
A Message is plaintext sometimes called cleartext. The process of disguishing
a message in such a way as to hide its substance is Encryption.
An Encrypted
message is also known as
CipherText. The process of turning
Ciphertext back into Palintext
is Decryption.
(If you want to follow the ISO 7498-2 standard, use the terms
"encipher" and "decipher".
It seems that some cultures find the terms Encrypt
and Decrypt offensive,
as they refer to dead bodies.The art of keeping messages
Secure is Cryptography, and it is practiced by Cryptographers. Cryptanalysts
are Practitioners of Cryptanalysis,
the art and science of breaking Ciphertext.That is, seeing through the disguise.
The branch of Mathematics encompassing
both Cryptography and Cryptanalysis is Cryptology
and its Practitioners are
Cryptologists.
Authentication,
Integrity and Nonrepudation
In addition to providing confidentionality,Cryptography is often
used for other
jobs such as
Authentication. It should be possible for the receiver of a message to
ascertain its origin
An Intruder should not be able to masquerade as someone
else.
Integrity. It should be possible for the receiver of a message to verify
that is has not been modified in transit. an intruder should not be able to
substitute a
false message for a legitimate one.
Nonrepudation. A sender should
not be able to falsely deny later that he sent a message.
These are vital requirements
for social interaction on computers, and are Analogous
to face-to-face Interactions.
That someone is who he says
he is ... that someone's credentials -whether a
driver's license, a medical degree, or a passport- are valid ... that a document
purporting to come from a person actually came from that person ... These are
the things that Authentication, Integrity and
NonRepudation provide.
Algorithms
and Keys
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