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