Chapter 3: Security Engineering Flashcards
(172 cards)
5 Symmetric Block Cyphers
EDB, CBC, DES, 3DES, AES last two are bay far most common 3DES very processor intensive
Abstraction
hides unnecessary data from user
access control matrix
a table defining what accesss permission exist between subject and object.
AES
Most common ecryption algorithm
what block cypher does bla bla bla:
AES
default standard for most apps.
AES Finalists
MARSRC6Rijndael - Winner!SerpentTwofishAES has four functions: SubBytes, ShiftRows, MixColumns, and AddRoundKey.
AES winner from 5 finalists
Rijndael was chosen and became aes.
AH
Authentication Header provides Auth and integrity for each packet of network data. provideds dig. signature protects against replay attacks.
Algorithm
a collection of all the math functions can be performed.
block of data goes though a bunch of math functions…
we want confusion…good strong math.
diffusion plain text intesperced with cypher text adds to confusion…
Permutation- rounds of encryption.
Kerkoff… principle
ALU
Algorithmetic logic unit and control unit performs math functions fed by the control unit
Aspects of Asym Cryptography
PAIN
Privacy, Authenticity, Integritiy, Non- Repudiationdd
Privacy = Every - user has a key pair private and public.
the two key’s are mathimatically related..
aka public key cryptography
Authenticity = sender encrypts with private key (random info) like time of day sent.
Integrity - Hashing comapre hashing that no change has happened.
Asymmetric Crypto - Inegrity Examples
MD5, SHA-1, SHA 256
Bell-Lapadula
It is focused on maintaining the confidentiality of objects. Protecting confidentiality means not allowing users at a lower security level to access objects at a higher security level.no read up no write down
*****all about confidentiality protecing gov secrets!
Bibba
Integrity of Information no read down no write up.
“Down Data is Dirty”
worried about integrity
Birthday Attack
Attempt to cause hash collisions.
it is based on the idea that it is easier to find two hashes that happen to match than to produce a specfic hash. “dump luck”
Block Cyphers
Symmetric Encryption encrypt blocks of data each round 56bit for DES, 128,192, 256 for AES
uses:
Confusion: carried out through substitution
Diffusion: is carried out though transpositon
Blowfish & Twofish
Blowfish and Twofish are symmetric block ciphers created by teams led by Bruce Schneier, author of Applied Cryptography. Blowfish uses 32- through 448-bit (the default is 128) keys to encrypt 64 bits of data. Twofish was an AES finalist, encrypting 128-bit blocks using 128- through 256-bit keys. Both are open algorithms, unpatented, and freely available.
Bollard
A security barrier for a car.
Brewer-Nash
aka chinese wall avoid conflict of interest by assigning someone to one item.
burn rating
2 hrs.
Ceasar Cipher
- Simple Substitution
- Shift Characters 3 spaces
- A=D, B=E, C=F, etc
- Substitusion Ciphers are subject to pattern analysis.
Chaining Feedback in Stream Modes called feedback
seeds the previous encrypted block into the next block to be encrypted. This destroys patterns in the resulting ciphertext.
Chosen Ciphertext Attack
An attacker can see whatever they want in palin or ciphertext. They have compromised a workstation. Sometimes called a lunchtime or midnight attack.
chosen plaintext attack
attacker can see the full text excrypted and decrypted. Usually the attacker has initiated the message.
you now have both and can compare them.
Cipher
a crypographic algorithm