Discrete Math › Section G · Additional topics › Topic G.4
Cryptography: number theory at work
Every secure website relies on calculations that are easy to do and believed to be infeasible to undo. This topic shows how the modular arithmetic of the previous topics becomes RSA, a public-key system in which anyone can lock a message but only one person can unlock it.
In this topic
- Why secrecy needs mathematics
- Shift ciphers: arithmetic mod 26
- The idea of public-key cryptography
- RSA key generation
- Encrypting and decrypting
- Worked example: fast modular exponentiation
- Worked example: a toy RSA system
- Why RSA is believed secure
- Signatures, hashing and the quantum threat
- Common mistakes to avoid
- Key takeaways
This topic is part of Wuanberri Pro. Checking your access…