WGU D830 OA - Introduction to Cryptography |
{LATEST 2026/ 2027 UPDATE} COMPLETE
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Terms in this set (240)
Cryptology The art and science of making and breaking
"secret codes
Cryptography The making of "secret codes."
Cryptanalysis The breaking of "secret codes."
Crypto A synonym for any or all of the above (and
more), where the precise meaning should be
clear from context.
cipher or used to encrypt data.
cryptosystem
plaintext normal text that has not been encrypted
Cryptosystem it is an implementation of cryptographic
techniques to provide information security
services (such as confidentiality and
integrity).
,Ancient Egypt The earliest known encrypted text found in
Egypt dates back to (nearly) 1900 BC.
Hieroglyphics on pharaohs and dignitaries
tombs had been hiding secrets, and were
disclosed (nearly) four millennia later. Secrets
were represented as symbols (i.e.
hieroglyphics), unreadable to those who did not
(and still do not) know the
hieroglyphics alphabet.
Greece. In 500s BC, Greeks developed cylinder
messages. The cipher made use of a baton
(called scytale). Each baton round had the
capacity to write letters. represents the secret
key. First, a parchment was wound up in spiral
around the baton. Second, the text to be
encrypted was written on the parchment in
straight lines (in rows).
Third, the parchment was unrolled; and it
represented the ciphertext. The recipient of the
ciphertext was required to possess a baton
(with the same diameter than
that of the sender) on which the received
parchment was wound up to recover the
plaintext. Figure 2.3.2 illustrates an example of
a message encryption using the Greek
scytale. The plaintext is TWO THOUSAND
SOLDIERS ONSITE ON SATURDAY; spaces
are removed before writing the plaintext
on a parchment
, wound up around a baton with a diameter of six
letters. When the parchment is unrolled, the
yielded ciphertext is
TUOSEUWSLOOROADNNDTNISSAHDEIAYOS
RTT.
Rome With no doubt, the most known cipher was
developed in Rome 2000 years ago, and
referred to as Caesar's cipher. The code
was mainly used to secure
communications between commanders and
troops on battlefields or between Rome and
provincial governors. Caesar's cipher is a
substitution cipher, where a letter is shifted by
some fixed position number; i.e. letter at
position in alphabet is replaced by letter at
position . This number, , was the secret key of
the cipher.
Caesar's cipher is presented in more detail in
Section 5.8.
Vigenere's cipher In the 1500s, Blaise de Vigenere made
improvements to Caesar's cipher. A 26-by-26
table is used to substitute letters, so that the
same letter is not always replaced by the
same letter as Caesar's cipher does. This is
the base concept of
polyalphabetic ciphers, which are harder to
break than Caesar's cipher. Vigenere's cipher
is presented in more detail in another
chapter.
{LATEST 2026/ 2027 UPDATE} COMPLETE
ACTUAL AND AUTHENTIC EXAM | BRAND
NEW!
Leave the first rating
Terms in this set (240)
Cryptology The art and science of making and breaking
"secret codes
Cryptography The making of "secret codes."
Cryptanalysis The breaking of "secret codes."
Crypto A synonym for any or all of the above (and
more), where the precise meaning should be
clear from context.
cipher or used to encrypt data.
cryptosystem
plaintext normal text that has not been encrypted
Cryptosystem it is an implementation of cryptographic
techniques to provide information security
services (such as confidentiality and
integrity).
,Ancient Egypt The earliest known encrypted text found in
Egypt dates back to (nearly) 1900 BC.
Hieroglyphics on pharaohs and dignitaries
tombs had been hiding secrets, and were
disclosed (nearly) four millennia later. Secrets
were represented as symbols (i.e.
hieroglyphics), unreadable to those who did not
(and still do not) know the
hieroglyphics alphabet.
Greece. In 500s BC, Greeks developed cylinder
messages. The cipher made use of a baton
(called scytale). Each baton round had the
capacity to write letters. represents the secret
key. First, a parchment was wound up in spiral
around the baton. Second, the text to be
encrypted was written on the parchment in
straight lines (in rows).
Third, the parchment was unrolled; and it
represented the ciphertext. The recipient of the
ciphertext was required to possess a baton
(with the same diameter than
that of the sender) on which the received
parchment was wound up to recover the
plaintext. Figure 2.3.2 illustrates an example of
a message encryption using the Greek
scytale. The plaintext is TWO THOUSAND
SOLDIERS ONSITE ON SATURDAY; spaces
are removed before writing the plaintext
on a parchment
, wound up around a baton with a diameter of six
letters. When the parchment is unrolled, the
yielded ciphertext is
TUOSEUWSLOOROADNNDTNISSAHDEIAYOS
RTT.
Rome With no doubt, the most known cipher was
developed in Rome 2000 years ago, and
referred to as Caesar's cipher. The code
was mainly used to secure
communications between commanders and
troops on battlefields or between Rome and
provincial governors. Caesar's cipher is a
substitution cipher, where a letter is shifted by
some fixed position number; i.e. letter at
position in alphabet is replaced by letter at
position . This number, , was the secret key of
the cipher.
Caesar's cipher is presented in more detail in
Section 5.8.
Vigenere's cipher In the 1500s, Blaise de Vigenere made
improvements to Caesar's cipher. A 26-by-26
table is used to substitute letters, so that the
same letter is not always replaced by the
same letter as Caesar's cipher does. This is
the base concept of
polyalphabetic ciphers, which are harder to
break than Caesar's cipher. Vigenere's cipher
is presented in more detail in another
chapter.
