#cryptography

3 articles

01 ·Security·FREE·PAPER·20 min read RSA from Scratch — The Number Theory Behind Public Keys RSA lets you publish a key that locks but cannot unlock. This builds it from congruence arithmetic up: key generation, the two modular exponentiations, and a line-by-line proof from Euler's theorem of why the message comes back — then a worked example small enough to check by hand, why factoring is the security assumption, and why textbook RSA must never be shipped without padding. 02 ·Security·★ MEMBER·10 min read TLS from Scratch — Key Exchange and Certificates Behind the padlock icon, your browser pulls off something strange: it agrees on a secret with a stranger, over a wire everyone can read. This walks through key exchange, certificates, and the TLS 1.3 handshake from zero, ending with why a man in the middle cannot win. 03 ·Security·FREE·13 min read Cryptography from Scratch — Symmetric Keys, Public Keys, and Hashes Cryptography isn't about producing unreadable text — it's about engineering an extreme gap in effort between people who hold the key and people who don't. We build up the three tools (symmetric, public-key, hashing) from zero, explain why factoring shows up at all, what a signature actually promises, and how every widely deployed cipher has eventually broken.