6-2 Flashcards
oldest recorded encryption method. used by ancient Romans. simple to implement, no tech assistance needed. simply choose a number by which to shift each letter. easy to break
caesar shift cipher
the most common single-letter word is __, the most common three-letter word is ___. with these two characteristics you can decrypt a Cesar shift cipher
a // the
a single substitution cipher where all characters are rotated 13 characters
rot 13
Hebrew scribes copying the book of Jeremiah used the ______ cipher. its simple, just reverse the alphabet. easy to break. A becomes Z and b becomes y.
atbash cipher
slight improvement to cesar shift cipher. you select the number by which to shift letters. if you select three alphabets, with (12,22,13). the first letter I shifted 12 letters, the second letter is shifted 22 letters, and the third letter is shifted 13 letters. the 4th letter is shifted 12 times, the fifth letter is shifted 22 times.
multi alphabet substitution
the most widely known multi alphabet cipher. invented in 1553 by giovani battista bellaso. was misattributed to blaise de vigenere.
vigenere cipher
most widely known transposition cipher. the output of the encryption was atcadwtaktan. to decrypt use the following
a t c a d w
t a k t a n
comes out as attackatdawn
rail fence
this cipher uses multiple substitutions in order to disrupt letter and word frequency. first cipher to last (+2, -1, +1, +3, +2, -1) . A+2=3 or c. T-1=s or 19
invented by giovani battista bellaso, its named after blaise de vigenere.
vigenere cipher
first to break this code was done by polish cryptoanalyst. first version invented by geman engineer arthur scherbiusr near the end of WWI.
breaking the code was done by reverse engineering a working enigma machine.
enigma
part of modern symmetric cryptography ciphers involves using ___________. well known to programmers and programming students.
binary operations
tor perform an ______ operation. take two binary numbers and compare them one place at a time. if both numbers have a one in both places then the result is a one, if not then the result is a zero.
AND
The ___ operation checks to see whether there is a one in either or both numbers in a given operation
OR
The ____ operation impacts you study of encryption the most. it checks to see whether there is a one in a number in a given placebut not in both numbers at that place.this is an In One but not the other operation. if you have a one in place and the other is a zero then the result is one.
XOR
if you xor the resultant number with the second number you get back the __________ number
first
binary encryption using XOR operation opens the door for some rather simple____________ .
encryption
