ECS1601 FINAL PAPER UPDATED
COMPLETE QUESTIONS AND CORRECT
ANSWERS BUNDLED REVIEW GUIDE
●● Caesar Cipher
Answer: Monoalphabetic cipher where letters are shifted one or more
letters in either direction.
●● ROT 13
Answer: Monoalphabetic cipher that shifts characters 13 characters.
Stands for Rotate 13. A would become N, B would become O, etc.
●● Scytale Cipher
Answer: Was a staff with papyrus or letter wrapped around it so edges
would line up. There would be a stream of characters which would show
you your message. When unwound it would be a random string of
characters. Would need an identical size staff on other end for other
individuals to decode message.
●● Multi-Alphabet Substitution Cipher
Answer: Doing something like +1, -2, +3 and shifting each character a
different amount to the left or right. For example, doing +1, -2, +3 with
dog would results in emj.
,●● Cipher Disks
Answer: A disk you rotated to encrypt/decrypt. Created by Leon Alberti.
Similar technologies were used in the Enigma machine. Considered the
forefather of modern encryption.
●● Vigenere Cipher
Answer: Invented by Giovan Battista Bellaso in middle 1553. Vigenere
created a stronger version of the cipher. Combining/Weaving Caesar
cipher. Not cracked until late 1800s. It is a cipher square with A to Z
across all the columns and rows. You then use a keyword to encrypt the
message. For example, if the message is cat, and the keyword is horse,
you would look up where c and h intersect on the table (which is j), then
where a and o intersect (o) and t and r (k). Cat would then be encrypted
as jok.
●● Playfair Cipher
Answer: Invented by Charles Wheatstone in mid 1800s. Lord Playfair
pushed use of it. Uses a 5x5 table and a key word. Rest of the alphabet is
placed on table in alphabetic order, skipping letters used in the keyword.
You break up the message into two character chunks and return a single
character value. If the letters appear on the same row of your table,
replace them with the letters to the right. If it is on the same column,
replace them with the letters below.
●● ADFGVX Cipher
,Answer: Invented by Colonel Fritz Nebel in 1918. It is a 6x6 grid with
ADFGVX at the top of each column and beginning of each row. The 26
letters and numbers 0-10 are placed randomly on the table. You then
replace each character of your message with two characters which are
represented by the column followed by the row each character is present
in.
●● Enigma Machine
Answer: Invented between World Wars, used by Germans and Japanese.
Data could be transmitted both via radio or printed on paper. Designed
so that when a key was pressed, the cipher text for that plain text was
different each time. Was a multi-alphabet cipher with 26 possible
alphabets.
●● Kerckhoff's Principle
Answer: We can expose everything but the private key and the data can
still be secure.
●● Issue with Symmetric Encryption
Answer: There's only one key, and it's difficult to only have both parties
who need the key to have it. It typically needs to be sent via another
medium than the message or else it could be compromised by the
attacker. Keys can also be sent via out of band (off the network being
used to send the message).
●● Binary Math
, Answer: Base 2 system instead of base 10 system.
●● Binary AND
Answer: If both numbers have a one in the same place, then the resultant
number is a one. If not then it is a zero
1st number - 1100
2nd number - 0100
--------------------------
Result - 0100
●● Binary OR
Answer: Checks to see if there is a one in either or both numbers in the
same place. If so, the resultant number is one, if not, it is zero.
1st number - 1100
2nd number - 0100
--------------------------
Result - 1100
●● Binary XOR (Exclusive OR) ⊕
Answer: Checks to see if there is a one in either number in the same
place. If so, the resultant number is one, if not, it is zero.
COMPLETE QUESTIONS AND CORRECT
ANSWERS BUNDLED REVIEW GUIDE
●● Caesar Cipher
Answer: Monoalphabetic cipher where letters are shifted one or more
letters in either direction.
●● ROT 13
Answer: Monoalphabetic cipher that shifts characters 13 characters.
Stands for Rotate 13. A would become N, B would become O, etc.
●● Scytale Cipher
Answer: Was a staff with papyrus or letter wrapped around it so edges
would line up. There would be a stream of characters which would show
you your message. When unwound it would be a random string of
characters. Would need an identical size staff on other end for other
individuals to decode message.
●● Multi-Alphabet Substitution Cipher
Answer: Doing something like +1, -2, +3 and shifting each character a
different amount to the left or right. For example, doing +1, -2, +3 with
dog would results in emj.
,●● Cipher Disks
Answer: A disk you rotated to encrypt/decrypt. Created by Leon Alberti.
Similar technologies were used in the Enigma machine. Considered the
forefather of modern encryption.
●● Vigenere Cipher
Answer: Invented by Giovan Battista Bellaso in middle 1553. Vigenere
created a stronger version of the cipher. Combining/Weaving Caesar
cipher. Not cracked until late 1800s. It is a cipher square with A to Z
across all the columns and rows. You then use a keyword to encrypt the
message. For example, if the message is cat, and the keyword is horse,
you would look up where c and h intersect on the table (which is j), then
where a and o intersect (o) and t and r (k). Cat would then be encrypted
as jok.
●● Playfair Cipher
Answer: Invented by Charles Wheatstone in mid 1800s. Lord Playfair
pushed use of it. Uses a 5x5 table and a key word. Rest of the alphabet is
placed on table in alphabetic order, skipping letters used in the keyword.
You break up the message into two character chunks and return a single
character value. If the letters appear on the same row of your table,
replace them with the letters to the right. If it is on the same column,
replace them with the letters below.
●● ADFGVX Cipher
,Answer: Invented by Colonel Fritz Nebel in 1918. It is a 6x6 grid with
ADFGVX at the top of each column and beginning of each row. The 26
letters and numbers 0-10 are placed randomly on the table. You then
replace each character of your message with two characters which are
represented by the column followed by the row each character is present
in.
●● Enigma Machine
Answer: Invented between World Wars, used by Germans and Japanese.
Data could be transmitted both via radio or printed on paper. Designed
so that when a key was pressed, the cipher text for that plain text was
different each time. Was a multi-alphabet cipher with 26 possible
alphabets.
●● Kerckhoff's Principle
Answer: We can expose everything but the private key and the data can
still be secure.
●● Issue with Symmetric Encryption
Answer: There's only one key, and it's difficult to only have both parties
who need the key to have it. It typically needs to be sent via another
medium than the message or else it could be compromised by the
attacker. Keys can also be sent via out of band (off the network being
used to send the message).
●● Binary Math
, Answer: Base 2 system instead of base 10 system.
●● Binary AND
Answer: If both numbers have a one in the same place, then the resultant
number is a one. If not then it is a zero
1st number - 1100
2nd number - 0100
--------------------------
Result - 0100
●● Binary OR
Answer: Checks to see if there is a one in either or both numbers in the
same place. If so, the resultant number is one, if not, it is zero.
1st number - 1100
2nd number - 0100
--------------------------
Result - 1100
●● Binary XOR (Exclusive OR) ⊕
Answer: Checks to see if there is a one in either number in the same
place. If so, the resultant number is one, if not, it is zero.
