As you can see, cryptography is a way that
we can conceal data from unauthorized access.
It is not a new concept, but rather an age
old study that has evolved into a tremendously
helpful aspect of security that helps us function
safely and securely.
Cryptography, along with the similar area of
study known as cryptanalysis, are actually
a subset of a broader study known as "cryptology".
Cryptology is the study of encryption and
decryption.
Cryptography and cryptanalysis are very similar
in name, but they are certainly two different
areas of study.
Let's explore each briefly.
Cryptography or encryption is the process
of converting ordinary messages or data (also
known as plain text) into something that is
not obvious or unintelligible.
This type of unintelligible writing is known
as cyphertext.
Cryptanalysis is the process by which we change
cyphertext into readable text again without
knowledge of a how that person encoded the
information in the first place.
This process is the way by which a person
or system cracks a code.
You should not confuse cryptography with cryptanalysis
because the method by which this person is
decrypting information is completely different.
Where a person undergoing cryptography is
using the proper procedures.
Someone undergoing cryptanalysis is doing
this by force.
Cryptography, as you've read and as you've
seen in the video, is one of the strongest
tools that we have in our arsenal to protect
against unauthorized viewers.
Encryption helps us protect our important
information and sensitive data as it travels,
and it can also help us protect data at rest.
like with our sensitive files on our computer.
Cryptography is a very advanced area of study
that requires a lot of technical know how.
Before we can look at this type of a protection
on a much deeper level we must first take
a look at some important terminology and information
associated with this area of study.
Cryptography is a word that is translated
from Greek to mean, "hidden writing".
With cryptography the hidden writing comes
in two forms.
These are called "codes" and "ciphers".
A code is a type of secret writing where we
substitute a word to mean something else.
A great example of the way that codes are
used in practice today is the United States
Secret Service's use of code names for US presidents,
their families, and other high profile people.
Originally, these code names were used in
place of real names over the wire to protect
the physical safety of individuals.
Generally, families will have names starting
with the same letter.
As you see in the picture here the Obama family
had names that began with the letter "R", Radiance,
Renaissance, Renegade, and Rosebud.
Today, these code names are used more often
out of tradition but are fascinating to read
about.
I've included an optional reading from Wikipedia
that lists all of the Presidential code names
that have been in use since they were first
implemented.
While codes are fascinating to talk about,
and like with secret service names, have lots
of interesting history, the type of secret
writing that we're going to spend the most
time discussing and utilizing are ciphers.
Ciphers, unlike codes are algorithms or sets
of rules that allow us to encrypt or decrypt
messages in a certain methodical way.
Some of the earliest ciphers date back to
1900 BC with the use of hieroglyphics.
Many people cite to this type of writing as
a cipher because it has a method for communicating
a language through a variety of symbols.
It is interesting to note however, that the
messages left by the ancient Egyptians were
unintentionally encrypted because this language
was no longer in use, it was up to archeologists
to try and to decipher what these messages meant.
It wasn't until the discovery of the rosetta
stone when historians were able to understand
and decipher some of the messages that were
written in this language.
Another example of a cipher is a "Spartan Scytale ("SKIH-tah-lee"), or sometimes they pronounce it, "SKY-tale".
This was a piece of cloth that was wrapped
around a spear and was used to communicate
messages in secrecy.
Here is a video of a Scytale in action.
