Module 3: Cryptography Flashcards
The word “cryptography” is derived from the Greek kryptos, meaning ____.
The word “cryptography” is derived from the Greek kryptos, meaning hidden.
The origin of cryptography is usually dated from about ____ with the Egyptian practice of ____.
The origin of cryptography is usually dated from about 2000 B.C., with the Egyptian practice of hieroglyphics.
The first known use of a modern cipher was by ____ (____ B.C. to ____ B.C.), who did not trust his messengers when communicating with his governors and officers.
The first known use of a modern cipher was by Julius Caesar (100 B.C. to 44 B.C.), who did not trust his messengers when communicating with his governors
and officers.
In recent times, ____ has turned into a battleground of some of the world’s best mathematicians and computer scientists.
In recent times, cryptography has turned into a battleground of some of the world’s best mathematicians and computer scientists.
The ability to securely store and transfer sensitive information has proved a critical factor in success in war and business.
cryptography
This is used in many applications like banking transactions cards, computer passwords, and e-commerce transactions.
cryptography
There are three (3) types of cryptographic techniques used in general:
- Symmetric-key cryptography
- Hash functions
- Public-key cryptography
What are the 6 classical encryption techniques?
- caesar cipher
- atbash cipher
- affine cipher
- keyword cipher
- playfair cipher
- vigenere cipher
A type of substitution cipher in which each letter in the plaintext is replaced by a letter of some fixed number of positions down the alphabet.
caesar cipher
Solve the caesar ciphertext with a shift of 7:
Kvu’a qbknl h ivvr if paz jvcly
Don’t judge a book by its cover
Solve the caesar ciphertext with a shift of 3:
khoor
hello
This was originally used to encrypt the Hebrew alphabet.
atbash cipher
It is one of the earliest known substitution ciphers to have been used, and is very simple.
atbash cipher
It simply reverses the plaintext alphabet to create the ciphertext alphabet. That is, “A” will be encrypted as “Z”, “B” as “Y”, and so on.
atbash cipher
Solve the atbash ciphertext:
FMREVIHRGB
UNIVERSITY
Convert the plaincipher to atbash ciphertext:
POLYTECHNIC
KLOBGVXSMRX
It is a type of monoalphabetic substitution cipher, where each letter in the alphabet is mapped to its numeric equivalent, encrypted using a simple mathematical function, and converted back to a letter.
affine cipher
Each letter is enciphered with the function (ax + b) mod 26.
affine cipher
Each letter is deciphered using what formula in affine cipher?
inverse of a * (c-b) mod 26
To use this cipher method, construct the ciphertext alphabet, pick a keyword and write it down, ignoring repeated letters. Follow it with the letters of the alphabet that have not yet been used.
keyword cipher
It was the first practical digraph substitution cipher.
playfair cipher
The playfair cipher was invented in ____ by ____ but was name after ____ who promoted the use of the cipher.
The playfair cipher was invented in 1854 by Charles Wheatstone but was name after Lord Playfair who promoted the use of the cipher.
This cipher removes the letter “J”, creates a 5x5 table of the new cipher table starting with the keyword and followed by the remaining non-duplicated letters of the alphabet.
playfair cipher
It is a method of encrypting alphabetic text by using a series of interwoven Caesar ciphers, based on the letters of a keyword.
vigenere cipher
This cipher uses a 26×26 table with A to Z as the row heading and column heading.
vigenere cipher
This is the repeating keyword to satisfy the number of letters from the encrypted text in a vigenere cipher.
keystream
