Introduction to Cryptography Basics

Before diving into RSA, ECC, and PQC, let's start with the fundamentals in a simple way.

Imagine cryptography as a lock and key system for digital information. It protects data like emails, passwords, or bank transactions from being read or tampered with by unauthorized people.

There are two main types of cryptography:

Symmetric Cryptography:

Uses the same key for locking (encrypting) and unlocking (decrypting). It's fast but tricky to share the key securely. Think of it as a shared padlock where both you and your friend have the same key.

Asymmetric Cryptography (or Public-Key Cryptography):

Uses a pair of keys—a public key (like a lock anyone can use to secure a message) and a private key (only you have to unlock it). This is what RSA, ECC, and many PQC methods are based on. It's great for secure communication without pre-sharing keys.

RSA (Rivest-Shamir-Adleman)

RSA is one of the oldest and most widely used asymmetric encryption systems, invented in 1977. It's like the granddad of modern crypto.

How It Works

Imagine you have two huge prime numbers (primes are numbers only divisible by 1 and themselves, like 2, 3, 5). Multiply them to get a massive number (let's call it N). Factoring N back into those primes is incredibly hard for computers—it's like finding two specific needles in a haystack the size of the universe.

Strengths

→Proven and trusted; used in HTTPS, SSL/TLS, email encryption (PGP), VPNs, and digital signatures.

→Easy to understand and implement.

→Key sizes: Typically 2048-4096 bits for security.