Data Representation and Encryption

Select a course.

arrow_back

infoWhy this? Understanding how computers encode numbers, text, images, and sound allows us to reason accurately about digital data. Exploring encryption and hashing also helps us distinguish confidentiality from integrity and evaluate how information can be protected.

scheduleWhy now? Building on computer systems and digital media, we now formalise binary, hexadecimal, conversion, and arithmetic before applying representation to encryption and hashing. This knowledge supports the subsequent study of how data is addressed, transmitted, and protected across networks.

A bit is the smallest unit of digital data and is 0 or 1.
A byte is 8 bits.
Denary, binary, and hexadecimal are place-value systems: denary uses base 10, binary uses base 2, and hexadecimal uses base 16.
Hexadecimal uses the digits 0–9 and the letters A–F.
In denary, binary, and hexadecimal, each place-value column represents a power of the relevant base, allowing conversion between number bases.
Each hexadecimal digit maps directly to a 4-bit binary group.
Binary addition uses carry operations when sums exceed 1.
Character encoding maps symbols to numeric codes such as ASCII or Unicode.
The number of bits available limits how many unique characters can be represented.
Digital images are stored as binary values for pixel properties, such as colour values.
In images, higher resolution and colour depth increase quality but also increase file size.
Digital audio is stored as binary values for sampled sound.
Encryption converts plaintext into ciphertext using an algorithm and key, and decryption requires the correct key and method.
Symmetric encryption uses the same shared key to encrypt and decrypt.
Asymmetric encryption uses a public key and a private key, which support secure communication without sharing a single secret key in advance.
Hashing transforms data into a fixed-length "fingerprint" that cannot realistically be reversed; hashing is used to check integrity and is not the same as encryption.
The Caesar cipher is weak because it has very few possible keys.
Modern encryption uses large keyspaces that make brute-force attack impractical.

rocket_launchYou must be able to

Convert values accurately between denary, binary, and hexadecimal, and perform calculations in each number system.
Explain how simple text, image, and audio data are represented digitally.
Compare weak and strong encryption approaches by using keyspace size to explain resistance to brute-force attacks.
Distinguish the real-world contexts in which hashing is used from those in which encryption is used.

Curriculum Portal