How encryption keeps data private: symmetric and public-key crypto, RSA, AES and TLS, explained and implemented.
The capstone to our RSA series. The math checks out. Shipping it as written gets you breached. This is the nineteen-year-old attack that proves it, and what belongs in production instead.
Most JavaScript developers never call an RSA function directly. They verify an RS256 token, and two classic attacks turn that into an authentication bypass — both demonstrated here, both fixed by one line.
Two papers dropped at the end of March. Both said the same thing in different ways: the quantum threat to elliptic curve cryptography is closer than we thought.
I use AI as a tool. I'll say that upfront. Claude helps me write frontends faster. It handles search queries that Google stopped being useful for
A deep-dive into the full cryptographic stack powering every HTTPS connection — RSA-OAEP, AES-GCM, ECDHE key exchange, and a working TLS 1.3 handshake simulation, all built in pure Python from first principles.
Encryption transforms readable data into unreadable ciphertext that only someone with the right key can reverse. It's what makes HTTPS, messaging apps, banking, and password storage work. Here's how it actually functions.
Signing is encryption with the keys swapped, and that symmetry is exactly what makes the naive implementation breakable. Here are two forgeries executed against textbook RSA signatures, and what PSS does that hashing alone cannot.
JavaScript cannot do RSA with numbers. Not slowly, not imprecisely — at all. The largest modulus a Number can handle is 26 bits and RSA needs 2048, and the failure is silent. Here's the implementation that works and why.
Cipher.getInstance("AES") compiles, runs, encrypts, decrypts, and hands you the weakest mode in the box. Here is the OpenJDK source that makes that decision, and the line where ECB gets chosen for you.
Key generation works, encryption round-trips, the math is provably right — and an attacker can still recover the private key by timing your decryptions. Here are both defenses, measured, with what they actually cost.
RSA Encryption has always been amazing to me. It allows you to publish an encryption key – also known as e – without having to compromise your decryption key – known
Part 1 used 15-bit primes and only encrypted integers. Making it usable means generating 1024-bit primes and chunking bytes — and the standard way to do the second one silently destroys data on inputs the tests never cover.
