1. Cryptology Design Fundamentals
Grundlagen des kryptographischen Systementwurfs
Module ID: ET-IDA-048
, v20
Prof. W. Adi
Lecture-1
Historical Overview and Introduction
(Lecture Contents Summary)

2. Recommended References
Lecture slides would be offered at the beginning of each lecture in paper form Electronic access to class material in homepage: User : student Password: Crypto_Ready
Possible Readings:
1. Introduction to Modern Cryptography: Principles and Protocols
J. Katz, Y. Lindell, CRC Press 2007, 2014
2. Cryptography: An Introduction
By Nigel Smart
(3rd Edition) Free on the Web.
3. Network Security
Private communication in a public world
C. Kaufman, R. Perlman, M. Speciner, Printice-Hall 10th printing 2007, ISBN
Recommended basic reference handbook:
4. Handbook of Applied Cryptography
by Alfred J. Menezes, Paul C. Van Oorschot, Scott A. Vanstone
CRC Press (October 16, 1996) (available free of charge on the WEB)

3. Outlines Why Security ? The Evolution of Security Science
This introduction presents essential examples of the main course contents by demonstrating examples with minimum mathematics !
Why Security ?
The Evolution of Security Science
Traditional Security Systems Overview
Modern Security Systems Overview
Contemporary Security Trends

4. Open Information World scenario
Why Security ?
Open Information World scenario
Widespread
Expanding very fast
unlimited applications
Mobile-Commerce etc…
Over Million mobile devices
Light
Heating
Kitchen
Garage
Door
Gates
...
Remote
Control
Car
power -
line
CAN-Bus TV
Service
node
Global Information
Short-Circuit
(AAA Scenario)
Power Station
power line network
Internet
Wireless
Network
Anywhere
Any time
Any device

5. Evolution of Communication Networks
PSTN, IP, 2G, 3G, 4G Mobile Network Architecture
IN Services
Circuit/ Signaling
Gateway
Circuit Switch
Voice
PSTN
Public Switched Telephone Network
Circuit Network
Call Agent
Packet Network
(Internet)
Packet Gateway
Mobility Manager
IP Core
Network
2G-GSM
Radio Access Control
2G/2.5G 3G
Security threats are spread over the whole network!
4G …

6. Impacts of the Globalization of Information Technology !
Globalization (Borderless)
Unlimited resources
Unrestricted resources
Easy untraceable access
No national boarders/Law?
Manageability ?
controllability ?
Abuse-ability
Security is still a serious issue in most communication systems, and is a very essential one !!

7. Two Major Security Tasks
Authentication
Securely identify an entity
Secrecy
Keep data safe against illegal users
Security tasks require to deploy cryptographic mechanisms to be realized
Cryptography: is the science dealing with hiding information and data security questions

8. 1. Secret Key Cryptography
Overview Concepts

9. Secret Key Cryptography
(Symmetric System)
K-open = K-close
- Open and close using shared secret keys (mostly one shared key) !!
- Secret key agreement required !

10. Secret Key Crypto-System : mechanical simulation
SENDER
RECEIVER
Key = Z Secret key agreement Key = Z Z
Lock
Message
Message Z

11. Conventional Cryptography till 1976 : Secret Key systems
Known locks as Standard Ciphers
Security rests on the Cipher
Ciphering
De-Ciphering
Sender
Receiver
Y = E (Z,X) X
E ( Z,X ) X
D ( Z,Y )
Message
Channel
Message
Secret Key = Z Z
Secret Key Channel

12. 2. Public-Key Cryptography
Scientific Breakthrough 1976
Secure-Communication
without prior shared secret keyes

13. A B Sharing Secrets without prior exchange of secrets
Public-Key Cryptography Breakthrough 1976
(Diffie & Hellman)
“Mechanical Scenario”
Open Register A B
Secret key-A
Secret key-B
injection
injection
SHIELD
! Same thing !
Shared Secret

14. ( ) ( ) A B Example for Diffie-Hellman key exchange scheme 1976
Widely use in internet and banking ...
Open Agreement and Register
Shielding function is: y = (5 x) mod 7 A B
K-open-A= 6
5 3 = 6
K-open-B= 3
5 5 = 3
Secret key-A= 3
Secret key-B= 5
( ) 5
( ) 3
5 3
5 5
5 5 3
Shield
5 3 6
5 5.3
5 3.5
! same thing !
Z = 6

15. Public-Key Secrecy Systems
K-open
K-secret
- Open and close with different keys!!
- No Secret Key Agreement required
Two Major Schemes in Public Key Cryptography:
Diffie-Hellman Public Key exchange scheme
RSA public Key secrecy system

16. Basic Public Key Secrecy System (RSA system1978)
(Mechanical simulation: user B gets a secured message from A)
User A
User B
Public register
Ko= Kc-1
Close Kc
open
( )Kc (mod m) Kc M
MKc.Ko = M
(MKc)Ko Ko
MKc

17. Mathematical Model of a Public-Key Secrecy-system
(using asymmetric keys)
Sender
Receiver
Y = E (Zp,X) X X
Message
Message
E ( Zp,X )
D ( Zs,Y )
Channel
Secret-Key Zs
Public-Key Zp
Public Directory
Z.. Zp
Z... Zs

18. Identification, Signature ..
3. Authentication
Identification, Signature ..

19. International Mobile Equipment Identity Subscriber Identity Module
Secured Identity (Authentic Identity)
International Mobile Equipment Identity
IMEI (non-secured)
SIM (secured)
Subscriber Identity Module

20. GSM Authentication: Challenge-Response
Subscriber Identification Mechanism
Mobil-Station
Verifier-Station
Identity key
max. 128 Bit Ki
Random
Generator
Authentication request
128 bits RAND
RAND
RAND
A3/COMP128
A3/COMP128
Authentication
Result
32 Bit =
XRES
XRES
Authentication response
XRES
SIM Card

21. Secured Signature (Data Authentication) (source authentication)
Signing Process:
Checking Signature :
Signing key
Document
Data
Signature
Authentic
Signature Generator
Data
Signature
Checker
Data
Signature
Checking
key
Signed Document
Only designated person can sign!
Accept/reject document
Everybody can check the signature!

22. 4. Cryptographic Protocols
Secret Sharing, Security Management, Standards,
Mobile Security & Applications

23. Cryptographic Protocols
No Key Cryptography : Shamir’s 3-Pass Protocol
(Mechanical scenario)
User A
User B A
Pass 1 A B A A B A A A B
Pass 2 A B A B B B A B
Pass 3 B B

24. 5. Physical Security DNA-like Identity for Physical Units
- Unclonable Physical Units (PUFs)
- Clone-Resistant Physical Units

25. Best physical Identity: the born DNA-like provable identification
Biological DNA
Select
Markers
Chemical
Extractor
Chemical Markers
Identification by matching markers
Bio DNA: 248 combinations ≈3 · 1012
Biological DNA Identification:
Unclonable if the DNA-chain is not possible to store or simulate A B C D
Extract same marker A’ B’ C’ D’
Non-equal marker extracts A’ ≠ B’ ≠ C’ ≠ D’ ≠ ≠ ≠ 25 25

26. PUF: Physically Unclonable Functions
Electronic born DNA-like identification
PUF: Physically Unclonable Functions
(off-shelf unit)
Analogue
Response
Discrete
stimulation
(select marker)
Discrete
Extractor
Discrete
Identification
Response
Physical Unclonable Functions PUFs offer DNA like Identification Properties
PUFs are: Born unpredictable and unclonable physical VLSI properties.
In other words: PUFs are analogue non-linear, upredictable huge mapping (impossible to model or simulate) in a semiconductor VLSI device 26 26

27. Course objectives
The aims of this course is to give a basic understanding of the design fundamentals and tools used in modern information security systems
Some standards would be introduced to enhance technical and practical understanding
Course strategy: less proofs, more practical design hints!