Cryptography & Security Depth
Signature Course No. 205 — A Signature AI Socratic Coaching Course.
A New Kind of Learning
Socratic coaching, delivered by an agentic AI coach.
Not a course you watch. An AI coach you work with.
The Lighthouse Coach begins by discovering how you think about the subject, teaches what is missing, and gives you realistic practice before asking you to prove that you can use it. You may test out of concepts you already understand, while capstones turn the learning into a practical plan, decision, conversation, or other real-world result.
The curriculum is deliberately authored; the AI delivers it through coaching. It is not an AI randomly generating lessons.
A coach that teaches by asking — not by lecturing
The Lighthouse Coach is an AI Socratic coach built on Cognosco Learning's Cryptography & Security Depth course, in the Risk, Safety & Compliance category. It does not play videos at you. It holds a conversation: it asks you a question, listens to your answer, names the misconception it hears, affirms what you got right, and asks the next question — the way a great coach works in the room.
Every system makes the same quiet promises. This message was not read, this message was not altered, this person is who the screen says they are, this record existed on this date. Cryptography is the machinery that keeps — or fails to keep — those promises, and this course takes the machinery apart: what each construction protects, what it does not protect, and what breaks first.
You learn the primitives as promises with edges. How symmetric encryption turns a key into secrecy and why the mode matters as much as the cipher; why encryption alone never proves a message intact, and what message authentication adds; what a hash function promises and the exact arithmetic of how collisions arrive sooner than intuition says; and why randomness is the foundation everything else stands on.
Then you work the systems layer. How two strangers agree on a secret over a public channel, worked in full on numbers you can check; how certificates bind keys to names and where that chain of trust can be cut; how the key lifecycle is run — generation, storage, rotation, destruction; and how the whole apparatus is migrated, attacked from the side, and eventually replaced, including the post-quantum transition taught as a planning problem, not a date.
It works in two movements. First, Module 1 — The Primitives: What Each Construction Protects — work through Concepts 1–9, finishing with The Design Review; then, Module 2 — Systems: Composition, Lifecycle, and Change — work through Concepts 10–18, finishing with The Migration Plan.
Both capstones produce real artifacts — The Design Review, a cryptographic design review of a real document-storage system, taken apart promise by promise with a certification verdict a client firm could act on; and The Migration Plan, a sequenced migration and protocol plan for the same company as its older constructions reach the end of their life, closed with an attestation signed under the reviewer's standard.
The arithmetic discipline is part of the course. Every worked number recomputes exactly — a key exchange on a prime of 23, a toy public-key encryption built from primes of 5 and 11, password and entropy figures stated as exact counts — and every claim about which algorithms and standards are current is stated as of this writing, with a direction to check the current guidance before you act on it.
The course is self-paced and always on — roughly 30 minutes per concept, about 9 hours in full, taken in as many sittings as you like. You can type your answers, or talk out loud: the Voice Coach speaks its questions and listens to your spoken replies. Learners who already know the material can test out concept by concept.
This is the two hundred and fifth course in The Lighthouse Signature Series — the online counterpart to the one-day, in-person learning Cognosco Learning has delivered since 2002.
Course Facts
One full concept, coached end to end — free: verify your email and we’ll send you a link to start.
Already enrolled? Enter the course →
Diagnose → Learn & Practice → Prove → Capstone
Every learner moves through the same discipline a Cognosco instructor would insist on in the room.
Diagnose
The Coach starts where the course starts: with what you actually bring. A cipher has never been the weak point of a real system — the weak point is always the promise somebody thought it made. Every concept opens with three questions that locate where you actually stand, and your answers shape how deeply the Coach works the concept with you. Everyone begins with Module 1 — no skipping the foundations you only think you have.
Learn & Practice
Work each concept in conversation with the Coach — spoken or written — then practice it against realistic situations until it holds up.
Prove
Every concept ends in proof: answer the check cold and demonstrate the skill. Know it already? Test out and take credit immediately.
Capstone
Finish with two capstones — The Design Review for Module 1 and The Migration Plan for Module 2 — that pull the whole course together, and earn the certificate.
What You'll Learn
Three promises, kept separate. Secrecy, integrity, and identity are three different promises — most real-world cryptographic failures are one promise mistaken for another, and every concept in the course states which promise its construction keeps and which it leaves to something else.
Module 1 teaches the primitives. Symmetric encryption and its counting, modes and their per-message values, authentication and AEAD, hash promises and the birthday bound, entropy counted exactly, key exchange and public-key constructions worked by hand, and password storage priced against a stolen file.
Module 2 teaches the systems. Certificate chains and protocol handshakes read as arguments, the key lifecycle run as a discipline, deprecation and agility, side channels and the recurring implementation shelf, threat modeling, and the reviewer's standard itself.
And it teaches change as a skill. Everything expires — constructions age, implementations leak, standards move — and a design that cannot be changed is a design with a failure date already printed on it, so inventory, migration, and the post-quantum sequence are core material, not an afterthought.
What you will learn
- Explain what symmetric encryption, modes of operation, and message authentication each protect — and what none of them protect
- State the security properties of hash functions and reason correctly about collisions and the birthday bound, and judge randomness and entropy claims with exact counting
- Explain key exchange, public-key encryption, and digital signatures from worked small-number examples you can recompute by hand
- Read a certificate chain and a protocol handshake as arguments, run the key lifecycle end to end, and frame a post-quantum transition as an inventory and sequencing problem
Everything in the course
- All 18 concepts of Cryptography & Security Depth, in 2 modules
- A starting-point check first — the Coach finds where you actually stand before teaching
- Learn, Practice, Prove for every concept — no passive video watching
- A test-out on every concept: prove you know it and move on
- The Voice Coach: talk with the Coach out loud — it speaks, listens, and replies
- A personal Learner Record of your work across the course
- Two capstone exercises: The Design Review and The Migration Plan
- A printable session summary whenever you pause
- The Lighthouse Coach completion certificate (Signature Series)
- Your progress is saved as you go — stop anytime, resume where you left off
Built for people who build, buy, review, or sign off on systems that hold secrets
Software engineers and architects — who choose libraries, modes, key lengths, and protocols, and who need to know what each choice actually buys and what it silently leaves open.
Security practitioners going deeper — the foundations material is assumed, not re-taught; this course is the cryptographic layer itself: the constructions, their failure modes, and the review questions that catch them.
Technical managers, reviewers, and compliance staff with technical duties — who must tell a sound cryptographic design from a confident paragraph about one, and answer accurately what a system does with keys, passwords, and certificates.
Prefer to learn live and in person? The same material anchors Cognosco's one-day programs — browse the in-person catalog.
Start with The Design Review
$195 — introductory price. One payment. No subscription, no password to manage.
Here is exactly what happens when you enroll:
- Pay securely with Stripe — you are taken straight into the course
- Create your learner profile and begin the Module 1 starting-point check
- Save the access key you are given — it restores your enrollment on any device
- Learn at your pace; your progress is stored in your browser on your device
For the full voice experience, use Chrome and allow the microphone when asked. Typing your answers works everywhere, all the time. Questions before you enroll? Email hello@cognoscolearning.com.
More Signature Courses are coming
Cryptography & Security Depth is Signature Course No. 205. Leave your email and we'll send you news of future Signature Courses and Lighthouse updates as they are announced — nothing else.