Cryptography and Data Security Flashcards
Define Cryptography
A form of secret writing, any technique to disguise the meaning of a word to those who don’t know how to interpret it
Define Transposition cipher
Swap the ordering of letters around in some fixed pattern
Define Substitution cipher
Takes a letter and replace it with another letter
Define Man in the Middle
Someone intercepts a conversation between a user and application, either to eavesdrop or to impersonate one of the parties
Define One-Time Pad (OTP)
Single-use, pre-shared key shared by sender and recipient
What are some requirements for OTP
Requires true randomness (Atmospheric noise detected by radio receiver), security of the pad, and no reuse
Define Polyalphabetic ciphers
Any cipher based on substitution, using multiple substitution alphabets
What is the problem with Polyalphabetic ciphers
If the Man in the Middle knew the cipher’s algorithm, the code is broken not just for you but for everyone using the system
Define Kerckhoffs’s Principle
The concept that a cryptographic system should be designed to be secure even if all its details, except the key, are publicly known
Define Diffie-Hellman Algorithm
A key-exchange protocol that enables two parties communicating over a public channel to establish a mutual secret without it being transmitted over the internet
How does the Public Key/Private Key pairs work
You publish the public key online, so anyone can use it to lock up their message to you in a box
You keep the private key a secret, so only you know, and only you can open the messages encrypted with the public key
Anyone can encode a message to send to you using the public key, but only the private key can decrypt it
Define Symmetric cryptography
A symmetrical key is one that is used to both encrypt and decrypt infromation
Define Asymmetric cryptography
A process that uses a pair of related keys, one public key and one private key, to encrypt and decrypt a message and protect it from unauthorised access for use
