Week 2 Flashcards
(27 cards)
Encryption
The act of taking a message, called plaintext, and applying an operation to it, called cipher, so that you receive a garbled, unreadable message as the output, called ciphertext
What then two components of the cipher?
The encryption algorithm and the key
Encryption algorithm
The underlying logic of process that’s used to convert plaintext into ciphertext
Key
Introduces something unique into your algorithm
Cryptosystem
A collection of algorithms for key generation and encryption and decryption operations that comprise a cryptographic service should remain secure - even if everything about the system is known, except the key
Shannon’s Maxim
The system should remain secure even if the enemy knows exactly what kind of encryption systems you’re employing, as long as your keys remain secure
Frequency analysis
The practice of studying the frequency with which letters appear in a cipher text
Steganogrsphy
The practice of hiding information from observers, but not encoding it.
Symmetric key algorithm
Use the same key to encrypt and decrypt
Substitution cipher
An encryption mechanism that replaces parts of your plaintext with ciphertext
Steam cipher
Takes of a stream of input and encrypts the stream one character or one digit at a time, outputting one encrypted character or digit at a time
Block ciphers
The cipher takes data in, places it into a bucket or block of data that’s a fixed size, then encodes that entire block as one unit
Initialization vector
A bit of random data that’s integrated into the encryption key and the resulting combined key is then used to encrypt the data
What’s the Caesar cipher and an example of one?
It’s a type of substitution cipher and an example would be ROT13
RC4 (Rivest Cipher 4)
A symmetric stream cipher that gained widespread adoption because of its simplicity and speed
MAC (Message Authentication Codes)
A bit of information that allows authentication of a received message, ensuring that the message came from the alleged sender and not a third party
How does a keyed-hash message authentication code work?
Uses a cryptographic hash function along with a secret key to generate a MAC
Elliptic curve cryptography
A public key encryption system that uses the algebraic structure of elliptic curves over finite fields to generate secure keys
Hashing
A type of function of operation that takes in an arbitrary data input and maps it to an output of fixed size, called a hash or digest
Rainbow table
A table containing common passwords and their respective HASHes. Used by black hat hackers
Password salt
Additional randomized data that’s added into the hashing function to generate a hash that’s unique to the password and salt combination
Public Key infrastructure
A system that defines the creation, storage and distribution of digital certificates
Digital certificate
A file that proves that an entity owns a certain public key, and it contains info on the public key, the entity it belongs to, and a digital signature from another party that has verified the information
Certificate authority
The entity responsible for storing, issuing, and signing certificates
