Build the Signal Protocol
Build end-to-end encryption like Signal/WhatsApp: X3DH for asynchronous key agreement, the Double Ratchet for forward secrecy + break-in recovery, sender keys for group chat, and metadata-privacy techniques. The protocol behind 2 billion encrypted conversations daily.
advanced10 lessons4 chapters10 graded exercisesPython
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What you’ll have built
Chapter by chapter. Every step is a graded exercise.
- Foundations: X3DH
- Double Ratchet
- Sessions & Group Chat
- Production Pitfalls
Starts in Python — solve in the language you choose in the editor, same tests either way.
Curriculum
4 chapters, 10 lessons. Each lesson is a short read, one graded exercise, and a quiz.
- 1What Signal SolvesRead · exercise · quiz
- 2Identity / Signed / One-Time KeysRead · exercise · quiz
- 3X3DH — Initial Key AgreementRead · exercise · quiz
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