Compression Encryption and Hashing Flashcards
(21 cards)
asymmetric encryption definition
an encryption technique where a public key available to everyone is used to encrypt the data, and the data is decrypted by the paired private key known only by the recipient
dictionary coding definition
a type of lossless compression where text is searched for entries that match the entries in a dictionary
entries are substituted by a unique code which can then be translated
hashing definition
a one-way transformation of data into an abbreviated form called a has value
the hash value is used to validate login credentials like passwords or PINs without revealing the original data to hackers
lossless compression definition
a compression algorithm that retains all the data in the file by only storing the instructions needed to reconstruct the original file
no data is lost
lossy compression
a compression algorithm that removes non-essential data from a file leading to a noticeable decrease in accuracy of the data
data lost is non-recoverable
run-length encoding
a type of lossless compression where repeated occurrences of the same data (like several pixels of the same colour in an image) are stored as a single data value with their counts
symmetric encryption
an encryption technique where the same key is used to encrypt and decrypt data. a copy of the key must be transferred between both parties
what name is given to the public and private keys used in asymmetric encryption
key pair
name the two categories of compression
lossy and lossless
in which type of compression is the quality of a file not degraded
lossless
what is the purpose of encryption
to keep data secure during transmission
name one type of lossless compression
- run length encoding
- dictionary encoding
in which form of encryption do the sender and receiver share the same private key
symmetric encryption
how many keys are used in asymmetric encryption
two (one public and one private)
if person A wants to send a message to person B using asymmetric encryption, which key should they use to encrypt the message?
A: A’s public key
B: A’s private key
C: B’s public key
D: B’s private key
C: B’s public key
a message encrypted with B’s public key can only be decrypted with B’s private key, which only B has access to
what is said to have occurred when two key map to the same hash
a collision
in which kind of lossless compression are repeated characters replaced by one occurrence and the number of times to repeat the character
run length encoding
what name is given to the process of turning an input into a fixed size value
hashing
what data structure uses hashing to store information with constant lookup time
hash table
what is meant by compression
the process of reducing the space required to store a file
name two properties that a hashing algorithm should have
- low chance of collision
- quick to calculate
- output smaller than input
