IT Security//

Data security
Software security
Hardware security

---------------------
Physical security measures
Procedural security measures
Technical security measures


----------------------------
	Attributes of information //

Confidentiality
Integrity
Availability
Authenticity/Unrepudability

------------------------
	Security mechanism//

Encryption
Checksum
Redundancy
Firewall
Authentification
Authorization



Accounting
-------------------
	Three ways of providing information

Defense
deferrence
detecting
-------------
Identify your information resources
what kind of nsk each of these resources can be exposed?
How high is the risk?
     C-         I -   M
-----------------------
RESOURCE1     H-         H -  H
----------------------
RESOURCE1     H-         H -  H
----------------------
RESOURCE1     H-         L -  L
-----------------------



Designing of IT infrastructure Security //
1st stage: Analysis
   resourses &risk
   IT infrastructure
   functions

do not implement functions you are intended ti use
do not install or remove or (at least)stop unneeded services

---------------------
    Hardware

  Computer &servers
  Network devices
  Network topology
-----------------
  Software

  OS
  Service software
  Network topology
-------------

Personal

 skill
 habits

CONCLUSION for the 1st stage
 Security Policy
(general ,wide audience)
Operational Documents
(technical, for IT staff, implied by Security Policy)


2nd stage: implementation
 firewalls
 vpns
 certification authorities
 authentication & authorization
 antivirus software
 spam filters
 courses for the staff


All of these should form a logical &consisted system
A  good practice build onion security architecture


3rd stage :Monitoring
 review of logs
 intrusion Detection/Prevention
 Systems(IDS/IPS)

You always should log
 failed logins
 deny access to files/directories

4th stage: Reaction
  what to do?
  who is responsible for the doc
  what repairing actions are to be performed
  what prepare for incident investigation
  How to say to the public

TURN BACK TO STAGE 1





                                  CRYPROLOGY


CRYPTOGRAPHY                                        CRYPTOANALYSIS                      STEGANOGRAPHY(embedding the "real" message in a unsuspicious message)
  (secret message sent in clear way)                 "brute force attack"                             (clear text in a secret way)
  (plain text="real message			      "cryptanalitic attacks=exploit a vulnerability in the encyption method"
  ciphertext=ecrypted message
   key="secret" component allowing conversion of ciphertext to plain text(or reverse))


attacks on encryption algorithms
--attack with a known ciphertext(the weakest method of attack)
--you want tp reveal the plain text
--you want to find the encryption key

the attack is easier to perform if the cryptanalyst has more ciphertext encrypted with the same key

attack with a known plain text
--known=a number of ciphertext and at least one pair plain text-ciphertext

attack with a chosen plain text
--its possible to encrypt a plain text

attack with as chosen ciphertext(lunch-time attack)

encryption: plain text ->ciphertext
decryption: ciphertext ->plaintext
--------------------------------------------------------------
CRYPTOGRAPHIC ALGORITHMS
TRANSPOSITION(PERMUTATION)

            s e c u r i
            t y o f i t
            i n f r a s
            t r u c t u
            r e x y z w

     STITREYNRECOFUXUFRCYRIATZITSUW

 SUBSTITUTION
  example: Ceasar cipher (shift any letter by 3)

VHFXUL....
  improvement:Vigenare cipher


CIPHER -images of the letter 'A' in consecutive Caesar's ciphers

ONE TIME PAD(substitution cipher)
--the key length is as long as the message
--use every key only once
--keys are truly random

Unconditionally secure encryption algorithm

Conditionally secure encryption algorithms:
--either the time which must be spent on breaking the ciphertext is longer than the time by which the plain text must be kept secret
--or breaking ciphertext is more expensive than the value of plain text message

Algorithms are based on S-P(substitution-permutation) networks
               example :DES,AES
It should be practically impossible to deduce private key for a given public key.
examples:RSA :RSA