cryptography test Flashcards
(28 cards)
What is decryption?
The process of converting encrypted data back to its original format
What does it mean to decrypt data?
Turning encrypted data back to its original readable form
Why do we want to decrypt data?
To make encrypted information readable and accessible to authorized individuals or systems
What is the difference between asymmetric and symmetric encryption?
Symmetric encryption uses a single key for both encryption and deception while asymmetric uses a pair of keys a public and private key
Caesar Cipher - uses one shift forward and the negative shift backwards
Type of encryption: symmetric
Why: it uses the same key for encryption and decryption
Polyalphabetic cipher - uses the same word for encryption and decryption but decrypts with a backwards shift
Type of encryption: symmetric
Why: uses the same keyword just in reverse for decryption
RSA encryption - uses a public and a private key for encryption and decryption
Type of encryption: asymmetric
Why: uses two different keys, a public for encryption and a private for decryption so the keys aren’t identical
Decrypt this message. The Caesar Cipher shift is 6
se skyygmk
my message
What is frequency fingerprint?
The unique pattern of how often each letter or symbol appears in a piece of text
How can we use frequency fingerprint to decrypt when we don’t know the key?
We can use it to decrypt a substitution cipher of letters in the ciphertext to the known letter
What is a way to prevent a frequency fingerprint?
Use a poly alphabetic cipher or a more advanced encryption method
Complete the polyalphabetic cipher. The key is CAB
g j h h e g
difede
History: Pick two historic uses of encryption. Explain the following: (20 pts)
Event 1: enigma machine
Who (used the cipher):
The Germans and later allied code breakers
What (cipher was used):
The enigma machine was a device used by the German during World War II to encrypt military communications
When ( was the cipher used):
1930s-1945 during world war II
Why (was the cipher used):
Germans use it to keep their military plans secret
Confidentiality, Integrity or Authenticity. A data entry clerk mistakenly inputs incorrect data into a financial system, leading to inaccurate financial reporting
Integrity
An intruder tries to access a restricted area of a government building, but is denied entry due to the biometric access control system requiring fingerprint authentication.
Authenticity
An employee accesses a company document on a public Wi-Fi network, exposing sensitive data to potential eavesdroppers.
Confidenciality
A lawyer’s private conversation with a client is recorded without their knowledge through a compromised smartphone, breaching attorney-client privilege.
Confidenciality
A user tries to log into a social media account, but is required to complete a two-factor authentication process, ensuring that the access is legitimate.
Authenticity
A hacker modifies the source code of a company’s website, causing it to display incorrect information to its users.
Integrity
plaintext
Original readable data or message before encryption
ciphertext
Result of encrypting plaintext
shift
refers to the number of positions each keyed is moved
Substitution cipher where each letter is mapped to its numeric equivalent encrypted message and then mapped back to a letter
Affine
transposition cipher that encrypts a message by writing it in a zigzag pattern across multiple rows
Rail Fence