Modern Block Cipher Intermediate
AES
AES secures nearly everything: HTTPS traffic, encrypted disks, and government secrets alike. Here's how the Rijndael cipher transforms data, round by round.
17 min read
Encryption you can actually see.
153 interactive visualizers and breakers. From a Caesar shift to cracking real Enigma traffic with the Bombe.
Featured
Three good places to see how a cipher really works.
Classic Asymmetric Algorithms Intermediate
RSA
RSA made public-key cryptography practical for the world. Here's how it works, why it's secure, and where it's headed as quantum computing looms.
18 min read
Basic Classic Symmetric Advanced
The Enigma Machine
Learn how the Enigma machine worked: the WWII German cipher machine that produced a different substitution alphabet for every single keystroke. Its defeat by Alan Turing and Bletchley Park changed the course of the war.
17 min read
Browse by topic
153 articles in six areas, from pen-and-paper ciphers to post-quantum schemes.
Classical ciphers
20 articlesFrom the Caesar shift to the Enigma machine. Pen-and-paper and rotor ciphers, step by step.
Symmetric encryption
33 articlesBlock ciphers, stream ciphers and authenticated modes, including AES and ChaCha20.
Hashing and authentication
24 articlesHash functions, message authentication codes and password hashing.
Public-key cryptography
27 articlesRSA, Diffie-Hellman, elliptic curves and the protocols built on them.
Post-quantum cryptography
14 articlesLattice, code, hash and multivariate schemes designed to resist quantum computers.
Codebreaking
35 articlesAttack the ciphers yourself, from frequency analysis to the Enigma Bombe and RSA factoring.
Where to start
Pick a level. Each list is a short path through the site.
Beginner
No maths needed. Learn the core ideas.
Intermediate
Real algorithms, explained step by step.
Latest articles
- AES Modes of Operation: CTR, CFB, OFB, and XTS Modern Block Cipher Intermediate
- Breaking the ADFGVX Cipher Basic Classic Symmetric Breakers Advanced
- Breaking the Nihilist Cipher Basic Classic Symmetric Breakers Intermediate
- Breaking Toy ECC with Pohlig-Hellman Modern & Applied Cryptography Breakers Advanced
- Breaking RSA with Weak Keys: Shared Primes and Pollard's p-1 Modern & Applied Cryptography Breakers Advanced
- Breaking the Bifid Cipher with Simulated Annealing Basic Classic Symmetric Breakers Advanced
Go beyond the visualizer
Get new articles by email, with practical case studies and security notes that build on the interactive tools.
We respect your privacy. Unsubscribe at any time.