Mastering Python for Networking and Security

Introduction to cryptography

Cryptography can be defined as the practice of hiding information, and includes techniques for message-integrity checking, sender/receiver identity authentication, and digital signatures.

The following are the four most common types of cryptography algorithms:

• Hash functions: Also known as one-way encryption, these have no key. A hash function outputs a fixed-length hash value for plaintext input, and in theory it's impossible to recover the length or content of the plaintext. One way cryptographic functions are used in websites to store passwords in a manner that they cannot be retrieved.
• Keyed hash functions: Used to build message-authentication codes (MACs); MACs are intended to prevent brute-force attacks. ...