Domain 5 - Cryptography Flashcards
An encrypted message
Ciphertext
An unencrypted message
Plaintext
The science of secure communication
Cryptology
Encryption that uses one key to encrypt and decrypt
Symmetric encryption
Encryption that uses two keys: if you encrypt with one, you may decrypt with other
Asymmetric encryption
One way encryption using algorithm but no key
Hash function
This creates messages whose meaning is hidden
Cryptography
The science of breaking encrypted messages ( recovering their meaning)
Cryptanalysis
—– is a cryptographic algorithm
Cipher
Converts the plaintext into a ciphertext
Encryption
Turns a cipher-text to a plaintext
Decryption
True or false. Cryptography can provide confidentiality and integrity and does not directly provide availability
True
True or false. Cryptography can also provide authentication and non repudiation
True
This means the order of the plaintext should be dispersed in the cipher text
Diffusion (transposition or permutation)
This means that the relationship between the plaintext and cipher-text should be confused (as random) as possible
Confusion (substitution)
It describes how long it will take to break a crypto systems ( decrypt a cipher-text without a key)
Work Factor
Is a cipher that uses one alphabet
Mono alphabetic cipher
It’s a cipher that uses multiple alphabets
Poly alphabetic cipher
Mono alphabetic ciphers are susceptible to frequency analysis. True or false
True
Three primary types of modern encryption
Symmetric
Asymmetric
Hashing
Describes the process of selecting the right method(cipher) and implementation for the right job, typically at an organisation wide scale
Cryptographic protocol governance
These are stylised pictorial writing used in ancient Egypt
Hieroglyphics
An ancient cryptography that uses strip of parchment that was wrapped around a rod
Spartan scytale
Is a mono alphabetic rotation cipher used by Julius Ceasar
Caesar cipher
This uses mono alphabetic cypher rotated 13 characters
Rot-13
Is a poly alphabetic cypher that is related 26 times to form a matrix
Vigenere cipher
These have two concentric disks, each with an alphabet around the periphery. They allow both mono-alphabetic and poly alphabetic encryption
Cipher disks
Also called wheel cypher. It had 36 wooden disks, each with 26 letters in random order
Jefferson disks
Is a cipher that uses whole words from a well known text such as a dictionary. To encode, agree on a text source, and note the page number, line, and word offset of each word you would like to encode
Book cipher
Is a cipher that uses well known texts as the basis for their keys but instead of using whole words, they use modulus math to add letters to each other
Running key cipher
This cipher assigns a code word for important people, locations , and terms
Code books
This uses identical paired pads of random characters, with a set amount of characters per page. It is the only encryption that is mathematically proven to be secure
One time pad
One time pad should meet the following three conditions to be secure
- The characters on the pad are truly random
- The pads are kept secure
- No page is ever used
The first known use of one time pad
Vernam cipher
Is a class of cryptographic devices known as rotor machines
Hebert machines
This looks like a large typewriter and finger wheels added use in the World War Two for cryptanalysis
Enigma
Is a cryptography law that was designed to control the export of critical technologies to iron curtain countries during the Cold War
Coordinating committee for Multilateral Exports Control (COCOM)
This law was initiated in 1996 when COCOM ended. It involves many more countries including Soviet Union countries. It also relaxed many of the restrictions on exporting cryptography
Wassenaar Arrangement
Is a mode of symmetric encryption where each bit is independently encrypted
Stream cipher
Is a mode of symmetric encryption where blocks of data each round is encrypted
Block cipher
Is used in some symmetric cipher to ensure that the first encrypted block of data is random
Initialisation vector (IV)
This seeds the previous encrypted block into the next block to be encrypted. It destroys the patterns in the resulting ciphertext
Chaining (also called feedback in stream mode)
Is a form of encryption that uses a 64 bit block size ( meaning it encrypts 64 bits each round) and a 56 bit key
DES Data Encryption Algorithm - DEA