My Skill Lab
CybersecurityIntermediate

Cryptography Fundamentals

Hashing, symmetric/asymmetric encryption, TLS and PKI — practically.

Taught by Kiran Basnet · Security Engineer

What you'll learn

  • Explain which security property hashing, encryption, MACs and digital signatures each provide
  • Hash data and store passwords correctly with SHA-256, HMAC and Argon2id
  • Encrypt and decrypt data with AES-GCM while handling keys and nonces safely
  • Generate key pairs and create and verify digital signatures with OpenSSL
  • Inspect X.509 certificates, create a CSR and explain how a chain of trust is validated
  • Trace a TLS 1.3 handshake and spot common cryptographic implementation mistakes in code

About this course

Cryptography protects almost everything you touch online, yet it is one of the easiest things for engineers to get subtly wrong. This practical cryptography fundamentals course is for developers, security analysts and students preparing for security certifications who want to understand how encryption works and how to use it safely. You will learn what hashing, symmetric encryption and asymmetric encryption each guarantee, store passwords with Argon2id, encrypt data with AES-GCM, sign and verify files with RSA and elliptic-curve keys, and see how Diffie-Hellman key exchange gives forward secrecy. You will then read X.509 certificates, understand PKI and certificate authorities, trace the TLS 1.3 handshake with OpenSSL, and learn where post-quantum algorithms such as ML-KEM fit. Every lesson uses real tools: Python's cryptography library and the openssl command line. You need basic Python and comfort with a terminal; no advanced maths is required.

Course content

7 lessons
  1. 1What Cryptography Protects and What It Does NotThe security goals of cryptography, its main building blocks, and the rule of never rolling your own.Preview
  2. 2Hash Functions, HMAC and Password StorageFingerprint data with SHA-256, authenticate it with HMAC and store passwords safely with Argon2id.
  3. 3Symmetric Encryption with AESHow AES works, why cipher modes matter, and how to encrypt safely with AES-GCM and a unique nonce.
  4. 4Asymmetric Cryptography: RSA, ECC and SignaturesPublic and private keys, how RSA and elliptic curves compare, and signing files with OpenSSL.
  5. 5Key Exchange, Forward Secrecy and Post-QuantumHow Diffie-Hellman agrees a shared key over an open network, and what post-quantum ML-KEM changes.
  6. 6Certificates and Public Key InfrastructureX.509 certificates, certificate authorities, chains of trust, CSRs and automated renewal with ACME.
  7. 7The TLS 1.3 Handshake and Common Crypto MistakesTrace a TLS 1.3 handshake step by step, test servers, and avoid the mistakes that break real systems.