Chapter 8: Cryptography Flashcards
Transposition Cipher
Transposing or scrambling the letters
Caesar Cipher
Shift letters a certain number of spaces in the alphabet
Vigenere Cipher
Use a keyword to look up cipher text in a table, so that the encryption would use a different shift for each letter
ROT13
Shifts every letter 13 places
Steganography
Hiding a message in a medium such as a digital image, audio file, or other file.
least significant bit (lsb) method
Storing data in the least significant bits of the pixels of an image
Is symmetric or antisymmetric cryptography faster?
symmetric
Data Encryption Standard (DES)
- Uses 56-bit key
- Now considered insecure, replaced by AES
Triple-DES
Uses three DES keys
Advanced Encryption Standard (AES)
Supports 128, 192, and 256 bit key sizes, but default is 128.
AES256
Uses 256 bit key. Makes shit top secret.
CAST
Uses a 40-bit to 128-bit key and is very fast.
Blowfish
- 64-bit symmetric block cipher
- Twofish is similar and has 128-bit block
International Data Encryption Algorithm (IDEA)
128-bit key, similar to DES but more secure
One-time Pads
Use a key as long as the plaintext message and are used only once then discarded. So VERY secure
Forward Secrecy
If one key is compromised, subsequent keys will not also .
Called perfect when it is unbreakable.
How does an asymmetric encryption work?
Encrypts with the public key, decrypts with the private key
Public Key Cryptography (PKC)
Any two key encryption system
RSA
Most commonly used public-key algorithm, used for encryption and digital signatures
Diffie-Hellman Key Exchange
Used primarily to send keys across networks, not to encrypt and decrypt messages
Elliptic Curve Cryptography (ECC)
An option to RSA that uses less computing power than RSA and is popular in smaller devices like smartphones
ElGamal
Transmitting digital signatures and key exchanges
Ephemeral Key
A key that only exists for a single session
ECDHE
Elliptic Curve Diffie Hellman using an ephemeral key
3 Characteristics of a Hash Functions
1) It must be one way
2) Variable-length input produces fixed-length output
3) Hashing two different inputs does not give the same output
Secure Hash Algorithm (SHA)
Designed to ensure the integrity of a message
Message Digest Algorithm (MD)
No longer recommended for use hash
RIPEMD
Based on MD4, it is a hash