1.3.1 Compression, encryption and hashing Flashcards
what is compression?
he process of reducing the space
required to store a file
what are types of compression?
-lossy
-lossless
what is lossy compression?
when data is lost permanently in order to reduce file size
what is lossless compression?
no data is lost in the compression process
what happens when a lossy file is decompressed?
-when the file is decompressed, the data that was removed is re-created from the data that remains in the file
-the re-created data will never be an exact copy of the original
-instead, it will be an approximation of the original data
what happens when a lossless file is decompressed?
when the file is decompressed, the contents are identical to the original file
when is lossy compression used?
audio files, downloaded music from the internet (MP3)
when is lossless compression used?
images that must retain the highest level of quality (PNG)
what are types of lossless compression?
-run length encoding
-dictionary encoding
what is run length encoding?
a data compression technique that replaces repeated sequences of data with a single data value and a count of how many times it appears
what is encryption?
the process of converting a plain text message into cipher text
why is encryption used?
to keep data secure during transmission
what are the types of encryption?
-symmetric
-asymmetric
what is symmetric encryption?
-uses the same key for encryption and decryption
-faster than asymmetric encryption
-requires less processing power
(more efficient)
-less secure
-no authentication (sender can’t be identified)
what is asymmetric encryption?
-uses a public and private key
-keys work as a pair, one is used to encrypt and the other decrypts
-secure
-more scalable because the public key can be shared with multiple users
-slower/less efficient
-more processing power needed
