C4 RSA and PKI in payments

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Lesson C4: Key pairs, signatures and certificates, and where payments use RSA: EMV, TR-34, TLS.

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The opening of the lesson

Why it matters

Symmetric keys need a shared secret first. Public-key cryptography solves the bootstrap problem:

  • a chip card proves it is genuine to any terminal;
  • a key distribution host sends keys to a device it has never met;
  • two hosts set up TLS.

RSA, with certificates organised in a PKI, is still the workhorse in payments.

In the full lesson

  1. The concept
  2. Step by step: EMV offline data authentication (DDA)
  3. In the real world
  4. Common mistakes
  5. What to test

What module C4 covers →

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