OCR H446 · Component 01 · Computer systems
1.3.1 Compression, encryption and hashing
Lossy and lossless compression, run-length encoding, dictionary coding, encryption, symmetric and asymmetric keys, hashing, collisions, rainbow tables, salts, and checksums.
What to revise
Practise compression, encryption and hashing.
Start with these questions from the compression, encryption and hashing topic pack. In the workspace, explain each idea from memory, compare your reasoning with the feedback, then revisit the concepts that need practice.
Use the pack alongside your OCR H446 computer systems revision. Your self-reported confidence helps plan the next review; it is not an exam mark or predicted grade.
- Encode AAAACCCBB using (count,character) run-length pairs. If each count and character occupies one byte, compare sizes.Apply
- What is compression?Compression
- Why do we compress files?Compression
- What is lossy compression?Compression
- What is lossless compression?Compression
- How does run-length encoding work?Compression
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