Chapter 3: Security Engineering Flashcards
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
Cipher Block Chaining
is a block mode of DES that XOR’s the previous encrypted block of ciphertext to the the next block of plaintext to be encrypted.
Ciphertext Only Attack
Attacker has captured encrypted text on the network. Usually means all the attacker can do it brute force. not very successful
Clark-Wilson
users access object via contrained programs/user interface
enforece well-formed trasactions throught the access triple
Helps to enforce integrity of the data
“keep users out of your stuff or they’ll break it.”
Clipper Chip
encryption in telecom devices skipjack key used went defunct in ‘96
Collision
When two different documents product teh same hash it is called a collision.
Common Asymmetric alorithms 6
“buddy system”
**importamento**
- DSA
- RSA
- ECC (Elipitcal Curve Crypto)
- El Gamal
- Diffie Hellman
- Knapsack
If it ain’t in the list then it is symmetric
Write down before test
RSA and DSA - “the SA bros”
ECC and El Gamal “start with e’s”
DH (Diffie Hellman) and Knapsack - doogie hauser has a knapsack
common criteria
iternationally agreed upon standard for describing and testing security of IT products
Confusion
Good strong math complex math for substitution
CPTED
CPTED (Crime Prevention Through Environmental DesignProvides instruction on direction of the use of:Organizational (People)Mechanical (Technology, hardware)Natural Design (landscaping, natural environment)
CPU Cycles
- Fetch - retrieves instruction from application
- Decode - control unit deciphers teh instruction and directs data from sys memory to ALU
- Execute - control and alu performs the math
- Store - result is stored in memory.
cpu modes
priveledge more level 0
user mode level 3 - non root
Cryptoanalysis
Science of breaking ecrypted messages
Cryptography
Secret Writing - communication that can only be understood by recipient
Cryptology
Science of Secure communications
CSRF
uses session ID
grab session information if you
cross site request fogery
takes advantage of a website’s trust in a user.
DAC
Discretionary Access Control
- Security of an object is as the owner’s discretions
- Access is granted through and ACL (access control list)
- Commonly implemented in commercial products and all client based systemes
- Identity Based
***Microsoft uses this…all about the owner.
linux and unix
Datacenter Location
Not in basement because of floods Not on first floor because of trafficNot on top floor because of fireIdeally on 2nd or 3rd floorShould be located in center of the building to avoid data emanation
CipherText
PlainText +Initialization Vextor + Algorithm(aka Cipher) + Key.
Deluge System
Same as dry pipe but sprinker head is open - releases much water faaaaaaast. no good for data processing environment.
DES Electronic Code Book
does not use an initialization vector or chaining and patterns can be clearly visible in the resulting ciphertext.
Diffie-Hellman
First asymmetric alogrithm
Key agreement allows two parties to securely agree on a symmetric key via a public channel like the internet, with no prior key exchange.
secure key agreements without pre-shared secrets.
we can agree on the 5h number based on the info we already have.
Diffusion
Permutations Rounds
Digital Certificate
x.509 v4 stardard
provides authenticity of a servers public key.
via hash the compare the has
encrypted by the certificate authority.
Digital Signature
Hash + Sender Private key…
standard.guarantee’s non-repuditaion = integ & auth
require PKI
Discrete Algorithm
Discrete logarithms apply logarithms to ((((GROUPS)))), which is a much harder problem to solve. This one-way function is the basis of the Diffie-Hellman and ElGamal asymmetric algorithms. a logarithm is the opposite of exponentiation…much harder to compute.
Door Security
Hinges should be protectedHinges internal to the door provide protection for the hinges while still allowing door to open outwardlyPanic bar allows for quick evacuationKick plate provides cosmetic protection for doorStrike plate—T-shaped component of lock which provides reinforcementIn the event of power failure, electronic doors can:Fail secure: Fails locked. No evacuation. Only in facilities where value of what is being protected exceeds human lifeFail Soft: Opens outward, but door is locked to bar returnFail Safe: Door fails open (easiest to evacuate)On the CISSP exam never choose fail secure . Fail soft/safe is the best choice
DRAM
less expensive uses capacitors can leak charge
requires constant charge
Drawbacks to Symmetric Cryptography
out of band key exchange
not scalable
no authenticity, Integrity or Non-Repudiation
we only get privacy.
ECC
Elliptical Curve Cryptography
Asymmetric
Based on plotting point upon a curve
super fast and efficient..only designed to work with certain enviornments.
eeprom
being able to flash the bios with software.
electromechanical alarms
Most commonRely on a connection being brokenmagnet on door and frame. Alarm sounds if the connection is brokenWeight based systems based on the same concept
Elliptic Curve Algorithm
much stronger per bit than systems using discrete algorithms.
Enigma Machine
Enigma Machine/Purple Machines
used by germans and japs.
add rotors to incrase comlexity.
Exclusive or XOR
Bits are different answer is 1 same answer is 0
Facility Considerations CPTED
Improve Surveillance: Improve visibility and eliminate concealment opportunitiesAccess Control:Actively control traffic, direct visitors, limit accessTerritoriality:Providing the impression of a well-tended building provides a deterrentActivity Support:Ensure all areas of the facility are occupied at least occasionally. Use activities like meetings, luncheons to populate these area
Fail Soft
door works as normal allows people out not in.
Fencing
Controls entrance accessCan be costly and unsightlyHeights provide degrees of protection3-4 feet – deters casual trespassers 5-7 feet – too high to climb easily (preventive)8 feet with 3 strands of barbed wire – (preventive) Will discourage all but the most determined intruder
Firmware
PROM (Programmable Read-Only Memory) can be written to once, typically at the factory. EPROM (Erasable Programmable Read-Only Memory) and EEPROM (Electrically Erasable Programmable Read-Only Memory) may be “flashed,” or erased and written to multiple times.
Goals in Protecting Property
Most important goal is to protect life, property and operations
halon
halon good fatal to people though…
HASH
one way math = for integritiyhash on both sides sender/receiver to ensure integrity
assurance it hasn’t been corrupted.
all hash are fixed length..
Hash Collision
two pieces of text/documents create the same hash
HASH MAC
Message agreed upon symmetric key + agreed upon hash never truly as good as dig sig. with it true non repudiation reasonalble assurance of authenticity without the overhead of a PKI
Hashing Algorithms 3 main- know bit lengths 4 less known
MD5 128 bits
SHA1 160 bits
SHA -256
Less common:RipeMD, Tiger, Whirlpool Haval
one way math..