Week 4: Public Key Cryptography

Asymmetric Encryption

A cryptographic system that uses a pair of keys: a public key for encryption and a private key for decryption.

Public Key

A key that is shared openly. Anyone can use it to encode a message, but only the holder of the corresponding private key can decode it.

Computational Security

The concept that a cryptosystem is secure if breaking it would require more computational resources than are available to an adversary.

Trapdoor One-Way Function

A function that is easy to compute in one direction but hard to reverse, unless you have secret information (the 'trapdoor'). It is key to asymmetric cryptography

RSA

A widely used public-key cryptography system that relies on the difficulty of factoring large numbers.

Euler's Totient Function

A function that counts the positive integers up to a given integer n that are coprime to n.

Digital Signatures

An asymmetric cryptographic technique that provides authenticity and integrity by allowing a sender to sign a message in a way that can be verified by anyone.

Public-Key Infrastructure

A framework of hardware, software, policies, and procedures needed to manage digital signatures and public-key cryptography.

X.509

A standard defining the format of public key certificates used in PKI.

Elliptic Curve Cryptography (ECC)

A form of public-key cryptography based on elliptic curves, offering the same security with smaller keys compared to RSA.