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Applied Cryptography Intermediate

Hashing, symmetric vs asymmetric encryption, TLS and digital signatures — used correctly.

4 lessons 7 tasks
Lessons Quiz Certificate

📚 Lessons

1 Hashing vs encryption

Hashing is one-way (SHA-256, bcrypt) — used for integrity and password storage. Encryption is reversible with a key — used for confidentiality. Never "encrypt" a password when you should hash it.

2 Symmetric & asymmetric keys

Symmetric crypto (AES) uses one shared secret — fast, but key distribution is hard. Asymmetric crypto (RSA, ECC) uses a public/private key pair — solves key exchange and enables signatures. In practice systems combine both: asymmetric to exchange a symmetric session key.

3 TLS and digital signatures

TLS secures data in transit using a handshake that authenticates the server (via certificates) and negotiates session keys. Digital signatures prove authenticity and integrity: the sender signs a hash with their private key; anyone can verify with the public key.

4 Crypto best practices

  • Never invent your own algorithm — use vetted libraries.
  • Use authenticated encryption (AES-GCM) so tampering is detected.
  • Generate keys and IVs from a CSPRNG.
  • Rotate keys and protect them (KMS/HSM).
  • Prefer modern algorithms; retire MD5/SHA-1/DES.

📝 Tasks

7 tasks across 3 pages — multiple-choice and fill-in (type the answer). Score 70% or higher to earn your certificate.

🎓 Certificate of Completion

🔒 Pass the quiz above (70%+) to unlock your downloadable certificate.