Please enable JavaScript.

Coggle requires JavaScript to display documents.

Cryptography (Definitions (Cryptology - science of secure communications,…

- - - - speed
      - cryptographic strength per bit
    - - key must be securely shared
      - complicated distro
    - - Stream
        
        each bit encrypted independently
      - Block
        
        DES
        
        Data Encryption Standard (uses Lucifer)
        
        Effective key length of 56
        
        Lucifer was 168 bits
        
        Operating Modes
        
        ECB - Electronic Code Book
        
        SImplest/weakest form of DES
        
        Identical plaintexts w/ keys
        
        CBC - Cipher block chaining
        
        XORs previous encrypted block of ciphertext to the next block
        
        Chaining destroys patterns
        
        Encryption errors will propagate and destroy integrity
        
        CFB - Cipher Feedback
        
        Ciphertext goes backwards aka "Cipher Feedback"
        
        Superior to CBC
        
        Cipher errors still propagate
        
        OFB - Output feedback
        
        Uses subkey before it is XORed to plaintext
        
        Subkey not affeted by encryption errors
        
        Errors do not propagate
        
        CTR - Counter mode
        
        Turns block cipher into stream cipher
        
        No longer considered adequate
        
        3DES
        
        AES
        
        Block Sizes
        
        128
        
        192
        
        256
        
        Uses Rijndael
        
        Current U.S. standard symmetric block cipher
    - - Twofish was a candidate for AES
  - - - Factoring of prime numbers
      - Discrete Logarithm Problem
    - - Uses prime number trapdoor function
      - Most widely used asymmetric function
    - - Uses Discrete Logarithm Problem
      - IPSEC
      - Elgamal based on DH
    - - More crypto strength per bit
        
        Uses less power, CPU cycles
        
        Same level security w/ smaller key size
- - - - Hash Functions
        
        MD5
        
        SHA
        
        SHA-1
        
        SHA-2
        
        HAVAL
        
        128, 160, 192, 224, or 256 bits
        
        3, 4 or 5 rounds
        
        Faster than MD5
      - Digital Signature
        
        Asymmetric
      - HMAC
        
        Symmetric