Transcript A Key

Basic Security Issues
Saad Haj Bakry, PhD, CEng, FIEE
Saad Haj Bakry, PhD, CEng, FIEE
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Cost Issues
Issue
Fact
Virus
Damage
The damage of the “I Love Virus” (May 2000) was
estimated to be “$ 10-15 billion” with the majority of
the damage done in the first few hours.
(The virus destroyed files and sent itself to others
through MS Outlook Address Book)
Spending on
Data Security
Estimated by “IDC” (International Data Corporation).
“$ 6.2 billion” (1999) / “$ 14.8 billion” (2003)
Building a
Estimated by “Identrus” ( Consortium of Global
“Digital
Financial Companies) for financial organizations to
Certificate
provide trusted B-to-B e-Commerce.
Infrastructure”
“$ 5 – 10 million”
Saad Haj Bakry, PhD, CEng, FIEE
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Secure Transactions Requirements
Issue
Fact
Privacy
Integrity
Authentication
No Disclosure
No Alteration
Proof of Identity:
Sender to Receiver / Receiver to Sender
Non-Repudiation
Legal Proof of Transaction:
Message is Sent or Received
Availability
System in Operation
“S-Business”
Outcome: “Secure Business”
Saad Haj Bakry, PhD, CEng, FIEE
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Basic Data Security Terms
Term
Definition
Plaintext
Source text / Unencrypted data
Cryptography
Transforming “plaintext” to “cipher text” (encrypted
text) using a “cipher” and a “key”
Cipher text
Encrypted text / Incomprehensible data
Cipher /
Cryptosystem
A technique / A procedure / An algorithm (a computer
science term) for encrypting data / messages
A Key
A string of digits used to encrypt data (like a
password) / Longer keys lead to stronger encryption
Cryptanalysis
Breaking / cracking encyption
Saad Haj Bakry, PhD, CEng, FIEE
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Old Cryptographic Ciphers
Cipher
Substitution
Algorithm
Replacing “a” by “b”
“b” by “c”
“c” by “d”….
“information security”
becomes
“jogpsnbujpo tfdvsjuz”
of letters to become:
“odd” followed by “even”
“information security”
becomes
“ifrain-nomto scrt-euiy”
Substitution and
transposition together
(see above)
“information security”
becomes
“jgsbjo-opnup tdsu-fvjz”
Transposition Changing the sequence
Both
Example
Saad Haj Bakry, PhD, CEng, FIEE
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Secret-Key Cryptography
Symmetric: Sender / Receiver
Less Sophisticated: Relative to Public-Key
More Efficient: Sending Large Amounts of Data
Problem (1): S-R “Key Exchange”
Problem (2): Many Keys “One for Each Receiver”
Saad Haj Bakry, PhD, CEng, FIEE
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Secret-Key Cryptography
Receiver
Sender
Plain
Text
Symmetric Key Encrypt / Decrypt
Cipher Text
Communication Network
Cipher Text
Encrypt / Decrypt
Saad Haj Bakry, PhD, CEng, FIEE
Symmetric Key
Plain
Text
Sender
Receiver
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KDC: Key Distribution Centre
To Solve “Key-Exchange” Problem
KDC Shares a “Secrete Key”: With “Every User”
All Transactions: Exchanged Through KDC
S-R Session Key: Generated by KDC per Transaction
Session Key Sent to S-R : Using their Shared Keys with KDC
Problem: Centralized Security “Challenges to KDC !”
Saad Haj Bakry, PhD, CEng, FIEE
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KDC Operation
Transaction
Plain
Text
Sender
Initiation
1
Symmetric Key (S)
Plain
Text
Session
Key
Cipher
Text
Receiver
Symmetric Key (R)
Communication Network
Assignment
3
Symmetric Key (S)
Assignment
Symmetric Key (R)
Generation
Generation
2
Session Key
Saad Haj Bakry, PhD, CEng, FIEE
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KDC
Session
Key
2
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DES: Data Encryption Standard
A Symmetric Encryption Algorithm: 1950s
By US NSA (National Security Agency) & IBM
Key Length is “56 bits”: Short / Easy to Crack
Triple Use (3 Keys in a Row): For More Security
DES (K-1)
DES (K-2)
DES (K-3)
Being Replaced BY: AES
Saad Haj Bakry, PhD, CEng, FIEE
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AES: Advanced Encryption Standard
A Symmetric Encryption Algorithm
By US NIST: : to Replace DES
(National Institute of Standards & Technology)
Five Finalists
Under
Consideration:
2001
Saad Haj Bakry, PhD, CEng, FIEE
Criteria of Choice:
Strength
Efficiency
Speed
Other Factors
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Public-Key Cryptography (1/2)
Asymmetric: Sender / Receiver
Public Key:
Private Key:
Distributed Freely
Kept by the Owner
Started at the MIT
in 1976 by:
Whitfield Diffe
Martin Hellman
Saad Haj Bakry, PhD, CEng, FIEE
RSA P-K Algorithm:
Rivest / Shamir / Adleman,
MIT 1977, RSA Inc. 1982
Used by “Fortune 1000”
“e-Commerce Transactions”
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Public-Key Cryptography (2/2)
“Secret Key”
Exchange
Not Needed
The Two Keys are
“Mathematically Related”,
BUT Computationally
“Infeasible to Deduce”
Private Key from the Public Key
Per Organization:
One “Public Key”
 One“Private Key”
Not One “Secret Key”

per receiver.
Saad Haj Bakry, PhD, CEng, FIEE
Problem:
Requires high computer power /
Not efficient for data volumes /
Performance: Slower
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Public-Key: Case (1)
Customer
Organization
Customer
Public
Key
Problem:
Customer
Networ
k
Organization
Saad Haj Bakry, PhD, CEng, FIEE
Validation of
customer’s
identity
Organization
Private
Key
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Public-Key: Case (2)
Customer
Customer
Private
Key
Networ
k
Organization
Saad Haj Bakry, PhD, CEng, FIEE
Customer
Public
Key
Problem:
Proving the
identity
of the
receiving
organization’s
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Public-Key: Case (3) “Combination”
Customer
Organization
Public Key
Identities of both partners
are authenticated
Organization
Saad Haj Bakry, PhD, CEng, FIEE
Organization
Private Key
Customer
Private
Key
Networ
k
Customer
Public
Key
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KAP: Key Agreement Protocol
Subject of Agreement: Symmetric Secret Key
Secret Key: Suitable for Volumes of Data
Agreement Security: Use of Public Key
Public Key: Suitable for Limited Volumes
Protocol: Rules of Agreement Process
Saad Haj Bakry, PhD, CEng, FIEE
Digital Envelop
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KAP Example: The Digital Envelop
Sender
Encrypt (Message)
Using
Message:
“Plain Text”
“Secret Key”
Message: “Cipher Text” (S-K)
Encrypt
(Secret Key)
Using
Receiver’s
“Public Key”
“Digital
Signature”:
Possible
Message
“Cipher Text”
(S-K) Plus
Message: “Cipher Text” (S-K)
Message:
“Plain
Text”
Receiver
Decrypt
(Message) Using
“Secret Key”
Saad Haj Bakry, PhD, CEng, FIEE
“Secret
Key”
“Cipher SK” (P-K)
Decrypt
Receiver’s
“Private Key”
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Key Management
Theft (mishandling) v. Attack (cryptanalysis)
Key Generation: Secure “Long Keys”
Key Generation
Problem:
Sometimes choice is
from a small set
Saad Haj Bakry, PhD, CEng, FIEE
Recommendation:
Key generation
should be truly
“random”
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The “Hash Function”
Objective: Checking Message Integrity
Mathematical Function Applied to the Message “Contents”
Message
Message Digest
Hash Function
“Hash Value”
Simple Function: “adding up the 1’s of the message”
Collision: Messages with the same “hash value”
Chance of Collision: Statistically insignificant
Messages can be checked but not reconstructed from their hash value
Saad Haj Bakry, PhD, CEng, FIEE
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Digital Signature (1/2)
Objective: (P-K) Authentication / Integrity
S
E
N
D
E
R
Hash
Function
Message
Digest
Encrypt
Message:
(Receiver
Public Key)
Cipher Text
Message:
Plain Text
Receiver
“Message Integrity”
Hash
Function
Saad Haj Bakry, PhD, CEng, FIEE
Encrypt
(Sender
Private Key)
“Sender
Authenticated”
Electronic
Signature
Message:
Message:
Plain Text
Cipher Text
Decrypt
Message (Receiver
Digest
Private Key)
Message
Digest
+
Decrypt
(Sender
Public Key)
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Digital Signature (2/2)
Digital Signature:


Document Dependent
(based on message
contents)
Authentication &
Integration
Handwritten Signature:


Document Independent
(same for all documents)
Authentication Only
Use: US DSA:
“Digital Signature Algorithm”
Problem (Digital Signature): Non-repudiation
(proof that the message has been sent)
Saad Haj Bakry, PhD, CEng, FIEE
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Time-stamping / Non-Repudiation (1/2)
Objective:


Binding “time and date”
to digital documents
Important for electronic
contracts
Sender /
Receiver
Saad Haj Bakry, PhD, CEng, FIEE
Time-Stamping
Agency
Third Party:
Time-stamping
Agency /
Legal Witness
Sender /
Receiver
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Time-stamping / Non-Repudiation (2/2)
S
E
N
D
E
R
1
Message:
Cipher Text
2
Sender
Electronic
Signature
Time-stamping Agency:
• Input:
Ciphered & Signed Message
• Output:
Time & Date Stamp
Agency Stamp (Signature)
(Using the Agency’s
Private Key)
Proof of receipt may be required “same
route back” from the “receiver”
Saad Haj Bakry, PhD, CEng, FIEE
1
2
3
Time & Date
Stamp
4
Agency Stamp
(Signature)
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PKI: Public Key Infrastructure (1/2)
Objective:
Hierarchy
Authentication of Parties
in a Transaction
IPA
IPRA:
Policy Creation
Authorities
Internet Policy Registration
Authority
(The Root Certification Authority)
Saad Haj Bakry, PhD, CEng, FIEE
CA: Certification
Authorities
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PKI: Public Key Infrastructure (2/2)
CA take the
responsibility of
authentication
DC are publicly
available and are
issued / held by CA
in “CR: Certificate
Repository”
Saad Haj Bakry, PhD, CEng, FIEE
CA:
Certification Authorities
Using
Public Key Cryptography
DC: Digital Certificates
DS: Digital Signatures
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Digital Certificate: Structure
Field
Explanation
Name (Subject)
Serial Number
Individual / company being certified
Public Key
Public key of the individual / company
Expiration Date
Certification need to be renewed
Signature of Trusted CA
For confirmation
Other Information
Relevant / needed data.
Saad Haj Bakry, PhD, CEng, FIEE
For management / organization
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Digital Certificate: Signature of Trust
Public Key (Name / Subject)
OR
Hash Function
Private Key (CA)
Signature of Trusted CA
Saad Haj Bakry, PhD, CEng, FIEE
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Digital Certificate: Expiration
Need for Change of Key (Pairs)
Expiration Date:
Long use of key
leads to
vulnerability
Key Compromised:
Cancellation / Renew
CA has “CRL: Certificate Revocation List”
Saad Haj Bakry, PhD, CEng, FIEE
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Cryptanalysis
Key / Cipher-text
Relationship:
Objectives:


Attack “to break key”
Test “key strength”

“Statistical” nature

“Plain-text” knowledge
How: Analysis of encryption algorithm to find relations
between “bits of encryption key” and “bits of
cipher-text” in order to “determine key”
Saad Haj Bakry, PhD, CEng, FIEE
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SSL: Secure Sockets Layer (1/2)
Sender
by: Netscape Communications
also used by: MS Internet Explorer
Application Software
“Browsers”
Receiver
Application Software
Messages
SSL
“Message Interpretation”
SSL
(to protect Internet transactions)
TCP
IP
Virtual
Data-
Saad Haj Bakry, PhD, CEng, FIEE
Circuit
TCP/IP
-gram
TCP
IP
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SSL: Secure Sockets Layer (2/2)
Functions:


Protects “private information from source to destination”
Authenticates “receiver / server in a transaction”
Tools:


Public Key /
Digital Certificate
Session (Secret) Keys
PCI: “Peripheral Component
Interconnect” cards
Installed on “Web Servers” to
secure data over an entire
SSL transaction “from sender
/ client to receiver / server”
Saad Haj Bakry, PhD, CEng, FIEE
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SET: Secure Electronic Transaction
by: Visa &
Master-Card
Objective:
protecting
e-commerce
payment
transactions
Saad Haj Bakry, PhD, CEng, FIEE
Authenticating the
Parties Involved:
“Customer”
“Merchant”
“Bank”
Using “Public-Key
Cryptography
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Microsoft Authenticode
Objective: Safety of software ordered online
Authenticode is built into MS Internet Explorer
Authenticode interacts with Digital Certificates
Digital Certificates should be obtained by software publishers
Digital Certificates can be obtained from CA “VeriSign”
Saad Haj Bakry, PhD, CEng, FIEE
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Viruses / Worms
Viruses: Computer programs sent as
attachments or hidden in audio and video
clips / executable files attached to e-mail.
They can cause
“denial of service / loss of availability”,
“corruption / wipe out of files” /…
Worms: Independent (not attached)
Saad Haj Bakry, PhD, CEng, FIEE
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Types of Viruses
Virus
Description
Transient Attached to a program. It is activated
only when the program is run.
Resident
Stored in the computer, and only
activated when the computer is used.
Logic
Bomb
Triggered when a given condition is met:
Trojan
Horse
A malicious program hidden in a friendly
program / or simulates its identity.
“Time Bomb” (activated by time)
Saad Haj Bakry, PhD, CEng, FIEE
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Examples of Viruses
Example
Description
Melissa
Spread in MS document sent via e-mail. Activated
on opening to infect Outlook and send itself to
first 50 addresses. Also infects other files.
March 1999
I Love You
May 2000
Trojan Horse
June 2000
Timofonica
June 2000
Sent as an e-mail attachment, claiming to be a
love letter. Activated on opening to infect Outlook
and send itself to all addresses. Also corrupted
files, including system files.
Sent as an e-mail attachment (Video Clip) to give
attackers access to launch denial of service.
A worm, propagated through e-mail to the cellular
network of Spain to generate calls & messages.
Saad Haj Bakry, PhD, CEng, FIEE
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Denial of Service Attacks: (1/2)
Flooding: Flooding servers with data
packets “very high traffic” causing
“congestion” / “denial of service”
Targeting Routing Tables: Changing
“routing tables” directing packets to
certain addresses
“disabling certain network components”
Saad Haj Bakry, PhD, CEng, FIEE
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Denial of Service Attacks: (2/2)
Example (February 2000): “Distributed”
denial of service attacks shut down
“high traffic web sites”:
“Yahoo / CNN Interaction / Amazon / eBay / ..
Distributed Denial of Service: “Packet
flooding” comes from different sources
Saad Haj Bakry, PhD, CEng, FIEE
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Web Defacing
Definition:
Entering a web site illegally,
and changing its contents.
Example (Swedish Hackers, 1996):
Entered
USA CIA web site (www.odci.gov/cia).
Changes included:
“Central Stupidity Agency”
Hyper Links to “adult content” sites.
Saad Haj Bakry, PhD, CEng, FIEE
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Anti-Virus Utilities
Conventional They are reactive, going after
discovered viruses rather
Utilities
New Utilities
www.finjan.com
Well-Known
Producers
Saad Haj Bakry, PhD, CEng, FIEE
than discovering new viruses.
 Searches for executable
files attached to e-mail.
 Runs the files in a secure
area to test their effect
 McAfee: www.mcafee.com
 Norton: www.symantec.com
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Security Policies
Key to the security of the
Organization / Network / Information





Vulnerability
Possible Attackers
Possible Threats
Possible Damage
Data Theft
Saad Haj Bakry, PhD, CEng, FIEE

Response
Security Needs

Security V. Performance

www.cerias.com
www.baselinesoft.com
www.sans.org
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Cyber-Crimes
National Security Policy:
USA National Infrastructure Protection Act
Denial of Service Attack / Distribution of Viruses
(Federal Crimes: Fines & Jail Time).
Web
Sites
Saad Haj Bakry, PhD, CEng, FIEE
www.usdoj.gov/criminal/cyberc
rime/ compcrime.html
www.cybertime.gov
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CERT: Computer Emergency Response Time
Carnegie Mellon University:
Software Engineering Institute
For Security Support: (www.cert.org)
Incident reports of viruses / denial of service
CERT Security Improvement Modules (Tutorials)
More Help
Saad Haj Bakry, PhD, CEng, FIEE
www.irchelp.org/itchelp/nuke
44
Firewalls
Objective: Protecting private networks from
intruders outside the network (not inside)
(Safety Barrier: Incoming / Outgoing flow).
Prohibiting
data flow
not expressly
allowed
Saad Haj Bakry, PhD, CEng, FIEE
OR
Allowing
data flow
not expressly
Prohibited
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Kerberos (Free MIT System)
Need: facing internal challenges ( 70-90% of attacks are internal)
Objective: to authenticate users in a private network;
and to maintain the integrity and the privacy of
network communication
(using symmetric secret key cryptography)
Symmetric Secret Key Communications
Ticket Granting Service
Client
Kerberos
Authentication of
Client Identity
Saad Haj Bakry, PhD, CEng, FIEE
TGS
Network
Service
Authentication of Client Right
to Access Specific Service
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Biometrics (Identities)
Definition: Using unique personal information
to
identify a user. (reducing dependence on passwords)



Finger Prints
Eyeball Iris scan
Face scan


www.iriscan.com
www.keytronic.com
BAPI: Biometric Application Programming
Interface “MS Promise (Windows)”
Saad Haj Bakry, PhD, CEng, FIEE
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Steganography (Hiding Information)
Objective: To hide information within other information


Examples:
Proof of Ownership:
Message: David
Owen
Hidden Message: DO
Watermarks
Music recorded with
frequencies not
audible to humans
bank notes / papers /

Digital Watermark:
Adobe PhotoShop


Solutions
www.digimark.com
www.conginity.com
www.adobe.com
Saad Haj Bakry, PhD, CEng, FIEE
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Important “Security” Webs (1/3)
Subject
Web
RSA Algorithm
www.rsasecurity.com
PGP (Pretty Good Privacy):
Web.mit.edu/network/pgp.html
MIT P-K “Web of Trust”
Time-stamping
www.authentidate.com
US Legislation in
Information Security
www.itaa.org/infosec
Certification Authorities
www.verisign.com
www.thawte.com
Saad Haj Bakry, PhD, CEng, FIEE
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Important “Security” Webs (2/3)
Subject
Web
Netscape SSL:
www.netscape.com/security/index.html
Secure Socket Layer
developer.netscape.com/tech/
security/ss1/protocol.html
PCI: Peripheral
Component Interconnect
cards
www.phobos.com/products/
infamily.htm
SET: Secure Electronic
www.setco.org
www.visa.com
Transaction
www.visa.com/nt/ecomm/security/mail.html
www.mastercard.com
Saad Haj Bakry, PhD, CEng, FIEE
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Important “Security” Webs (3/3)
Subject
Web
msdn.microsoft.com/workshop/
security/authcode/signfaq.asp
 msdn.microsoft.com/workshop/
security/authcode/authwp.asp
MS Authenticode

Firewalls

Kerberos

Magazines

Saad Haj Bakry, PhD, CEng, FIEE
www.interhack.net/pubs/fwfaq
www.pdc.kth.se/kth-krb
www.networkcomputing.com/consensus
 www.scmagazine.com
 www.insightview.com
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Reference

H.M. Deitel, P.J. Deitel, K. Steinbuhler, eBusiness and e-Commerce for Managers,
Prentice-Hall, Upper Saddler River, New
Jersey, 2001
Saad Haj Bakry, PhD, CEng, FIEE
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