exchanging data (compression, encryption, hash) Flashcards
Learn all.
Explain compression?
Compression is the process used to reduce storage space required by a file, meaning you can store more files with the same amount of storage space. It is good for sharing files over the internet.
Explain Lossy Compression?
Lossy Compression is where file sizes are reduced while also removing some of its info. Results in more pixelated images etc.
Explain Lossless Compression?
Lossless Compression reduces the file size of a file without losing any of its info. When using Lossless the original file can be recovered. This is not possible with lossy.
What is Run Length Encoding?
RLE is a method of lossless compression where repeated values are removed and replaced with one occurrence of the data followed by the number of times it has been repeated.
What is Dictionary Encoding?
Another type of lossless compression. Repeated data is replaced with an index and compressed data is stored alongside a dictionary which matches the data to the index.
Explain encryption?
It is used to keep data secure when it’s being transmitted. A way of scrambling data to then be deciphered once it has reached its destination.
Explain Symmetric Encryption.
Both the sender and receiver share the same private key which they distribute to each other during a key exchange. This can be used to encrypt and decrypt data.
Explain Asymmetric Encryption?
2 keys are used. One public one private. Public can be published anywhere but private is kept secret.
How do they differ?
In symmetric encryption a single key can be used to encrypt and decrypt however asymmetric encryption messages encrypted with recipients public key can only be decrypted with their private key.
Explain Hashing?
Where a key is turned into a hash. Input > fixed value. A use is hash tables. This holds key-value pairs. Hash tables are used in databases.
