Crypto Fundamentals

Hash Functions

A hash function converts arbitrary input data into a fixed-size digest.

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"hello"
↓ hash
2cf24dba...

Important properties:

• The same input always produces the same hash.
• A tiny input change produces a very different hash.
• Recovering the original input from the hash should be computationally infeasible.
• Finding two different inputs with the same hash should be extremely difficult.

Blockchains use hashes for transaction IDs, block linking, Merkle trees, and data integrity.

Fundamentals

Primitive Types vs Wrapper Types

Primitive types store raw values, while wrapper types are objects that can be null and are required by generics/collections.

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int age = 18;
Integer nullableAge = null;

List<Integer> numbers = List.of(1, 2, 3);

Fundamentals

HTML

SEO (Search Engine Optimization)

• Use semantic HTML elements (<article>, <section>, <nav>, <header>, <h1><h2> etc.)
• Set meaningful <title> and <meta name="description" content="xxx"> for each page.
• Use of <alt> Attributes on Images
• Use <meta name="robots"> or robots.txt to control indexing.

Render Process

DOM + CSSOM => Render Tree
Layout(Size, Position) => Paint(Color, Background) => Composite
Recalculate Style => Reflow => Repaint => Compositing