Week 2 Flashcards
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
