Stelau courses / EPITA · EGE · ESG
Algorithms are building blocks. Understanding how they fit together is the first step towards understanding a system’s security.
01 / The common language
Symmetric and asymmetric cryptography, hashing, key agreement and randomness: watch data move, keys come into play and results appear.
Original GSAP course scenes. Values and parameters are simplified to explain the mechanisms; SHA-1 and small-number Diffie–Hellman examples are for teaching.
02 / The guiding idea
A certificate is a static file. An electronic passport combines protocols to authenticate a chip, establish a protected channel and control access to its data, including sensitive biometric fingerprints. The same questions connect them.
01Who holds which key?
02What is signed, encrypted or verified?
03What happens when a component is missing?
The course provides the foundations for reading these constructions and discussing their guarantees and limitations.
03 / Inside the course
01 / X.509
An identity, a public key and an authority’s signature. Watch the file take shape, from the digest to verification.
Teaching model: the signature covers the displayed data. A real X.509 certificate uses an ASN.1 structure and requires additional validation rules.
02 / TLS
Key agreement, authentication, encryption and derivation: identify what each component contributes to TLS.
Cipher-suite names include TLS 1.2 examples. TLS 1.3 negotiates key exchange and authentication separately. The diagram simplifies the exchanges.
03 / AES-128
Substitution, row shifting, column mixing and round keys: watch AES bytes actually change.
04 / RFC 6238
A shared secret, a time counter and an HMAC: follow a TOTP code calculation and its renewal window.
The first two rows illustrate simplified hashes. The lower calculation follows RFC 6238: HMAC, a 30-second counter and dynamic truncation. A TOTP code is computed locally; it is not an SMS.
04 / Learning by doing
The EGE syllabus combines illustrated teaching with team workshops. No prior theoretical knowledge of cryptography is required: the course progresses from the five building blocks to systems that combine them.
Workshop / Interception
Ten players. Three roles. Who controls the message?
Three at headquarters issue orders, three commandos must carry them out, and four enemies intercept and tamper with messages. Agree on a secret using Diffie–Hellman, then keep communicating when the enemy takes over the channel. Can you get the genuine attack order through?
Game rules · PDF in FrenchWorkshop / Cryptographic puzzle
Strong encryption. An unexpected way out.
2017: leaked NSA tools, a global attack, files held hostage… then traces of private keys found in memory on some Windows systems. In a team of five, reconstruct WannaCry’s cryptographic design and follow the trail. How could formidable encryption still leave a chance to recover the files?
Story and resources · in FrenchIdentity documents, Bitcoin, TLS, VPNs, messaging, visible digital seals and electronic signatures: practical cases to learn how to explain a mechanism, beyond naming it.
Keep experimenting
Continue with OIDApp and its CryptoLab: sign, tamper, verify and learn how OpenID protections work through hands-on experiments.
Explore OpenID / CryptoLabAt EPITA, EGE and ESG, the content adapts to the audience and available time. Let’s discuss your programme.
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