Domain 3: Cryptography Flashcards
Science of breaking encrypted messages to recover their meaning
Cryptanalysis
- Always hides the true meaning of a message
- Converts messages from plaintext to ciphertext
Cipher
Unencrypted message
Plaintext
Converts plaintext to ciphertext
Encryption
Turns ciphertext back into plaintext
Decryption
- Random number that acts as a placeholder variable in mathematical function.
- When function is executed, this item is replaced with a random number generated at the moment of processing for one-time use
Nonce
- Historical cipher
- To encrypt a message, you shift each letter of the alphabet three places to the right
Caesar Cipher
- Historical cipher
- A machine that used a series of three to six rotors to implement a extremely complicated substitution cipher
- Used by Germans on WWI
Enigma
- Historical cipher
- Machine used by Japanese in WWII for cryptosystems
Purple Machine
Out of the CIA triad what does cryptography provide?
Confidentiality and Integrity
The order of the plaintext should be dispersed in the ciphertext
Diffusion
The relationship between the plaintext and ciphertext should be as random as possible
Confusion
Use an encryption algorithm to replaces each character of the plaintext with another character
Cryptographic Substitution
Use an encryption algorithm to rearrange the characters of the plaintext, forming the ciphertext message
Permutation aka Transposition
- Key must be generated randomly without any known pattern
- Key must be at least long as the message to be encrypted
- Key must be used one time then discarded
One-Time Pads
In this cipher, the encryption key is as long as the message itself and is often chose from a common book (i.e. Moby Dick)
Running Key Cipher
Describes how long it will take to break a cryptosystem (decrypt a ciphertext without the key)
Work factor
Uses one alphabet, in which a specific letter substitutes for another
Monoalphabetic cipher
- Uses multiple alphabets
- i.e. Vigenere cipher
Polyalphabetic cipher
Logical functions that returns a true value when only one of the input values is true
Exclusive OR (XOR)
Process of selecting the right method (i.e. cipher) and implementation for the right job, typically organization-side scale.
Cryptographic Protocol Governance
- Key agreement algorithm
- Use discrete logarithms
Diffie-Hellman
- Part of the 3 major public key cryptosystems
- Uses discrete logarithms
- Extension of Diffie Hellman key exchange algorithm that depends on modular arithmetic
ElGamal
Linux systems use _____ to encrypt passwords and this is based on ______.
bcrypt
Blowfish
- Cryptographic systems of symbols that represent words or phrases, are sometimes secret, but don’t necessarily provide confidentiality
- i.e. “10-4” used by law enforcement
Codes
- Communication concept specific type of info is exchanged, but no real data is transferred
- i.e. Digital signatures and digital certificates
Zero-knowledge proof
- Info or privilege required to perform an operation is divided among multiple users
- Ensures no one person has sufficient privileges to compromise the security of the environment
- i.e. M of N Control
Split knowledge
Requires that a min number of agents (M) out of a total number of agents (N) work together to perform high-security tasks
M of N Control
What are the three main methods used to exchange secret keys securely?
- Offline distribution
- Public key encryption
- Diffie-Hellman exchange algorithm
- Part of the 3 major public key cryptosystems
- Depends on the difficulty of factoring the product of prime numbers
RSA
Name the 3 major public key cryptosystems for Asymmetric encryption?
- RSA
- ElGamal
- Elliptic Curve Cryptography (ECC)
