OCR Computer Science A Level: Compression, Encryption and Hashing

These flashcards cover key vocabulary terms and definitions relating to compression, encryption, and hashing concepts from the OCR Computer Science A Level lecture notes.

Compression

The process used to reduce the storage space required by a file.

Lossy Compression

A compression method that reduces file size by removing some information, potentially degrading quality.

Lossless Compression

A compression method that reduces file size without losing any information, allowing for the original file to be fully recovered.

Run Length Encoding (RLE)

A method of lossless compression that replaces repeated values with a single value followed by the count of repetitions.

Dictionary Encoding

A method of lossless compression that replaces frequently occurring data with indexed references to a dictionary of data.

Encryption

The process of scrambling data to keep it secure during transmission.

Symmetric Encryption

A type of encryption where the same private key is used for both encrypting and decrypting data.

Asymmetric Encryption

A type of encryption that uses a pair of keys, one public and one private, for secure data transmission.

Hashing

A process that turns an input (key) into a fixed size value (hash) using hash functions.

Collision (in hashing)

An occurrence when two different inputs produce the same hash output.

Hash Table

A data structure that holds key-value pairs and uses a hash function for data lookup in constant time.