1. Saad Haj Bakry, PhD, CEng, FIEE 1 Principles of Information Security Saad Haj Bakry, PhD, CEng, FIEE P RESENTATIONS IN N ETWORK S ECURITY

2. Saad Haj Bakry, PhD, CEng, FIEE 2 Information Processing Error / Volume Control Steganography Hash Function Symmetric (Private Key) Encryption Asymmetric (Public Key) Encryption Cryptanalysis Objectives / Contents Principles of Information Security

3. Saad Haj Bakry, PhD, CEng, FIEE 3 Information Processing (1) Source Encoding Coding signal in digital form. Compression Reduction of transmission bandwidth. Error Control Detection (and correction) of communication errors (noise). Traffic Padding Testing traffic volume (volume confidentiality) Principles of Information Security

4. Saad Haj Bakry, PhD, CEng, FIEE 4 Information Processing (2) Steganography Hiding Information within other informatiom. Hash Function Message summary to test integrity. Encryption Using encoding (encryption / enciphering) as means for protecting data from interception by unauthorized parties Cryptanalysis Breaking (cracking) encryption. Principles of Information Security

5. Saad Haj Bakry, PhD, CEng, FIEE 5 IT Security P RINCIPLE: Redundant Information to Detect / Correct Errors F ORWARD E RROR C ORRECTION: Hamming Reed-Solomon Codes Bose Chaudhuri Hocquenhem Codes F ORWARD E RROR C ORRECTION: Hamming Reed-Solomon Codes Bose Chaudhuri Hocquenhem Codes A CKNOWLEDGEMENTS: Echo Checking: Send Back ARQ: Automatic Repeat Request A CKNOWLEDGEMENTS: Echo Checking: Send Back ARQ: Automatic Repeat Request Error Control (1) Principles of Information Security

6. Saad Haj Bakry, PhD, CEng, FIEE 6 B YTE P ARITY C HECK 1001101 0 1 1234567 8 8 BIT No. BITS ODD PARITY EVEN PARITY Error Control (2) Principles of Information Security

7. Saad Haj Bakry, PhD, CEng, FIEE 7 B LOCK C HECKING 10011011 1234567 BIT No. BITS 8 PARITY BLOCK PARITY Error Control (3) Principles of Information Security

8. Saad Haj Bakry, PhD, CEng, FIEE 8 O BJECTIVES: C ONFIDENTIALITY FOR THE V OLUME OF T RAFFIC O BJECTIVES: C ONFIDENTIALITY FOR THE V OLUME OF T RAFFIC M ETHOD: Filling idle periods with meaningless data (packets) that can be detected by the receiver. (Volume Testing & Control) M ETHOD: Filling idle periods with meaningless data (packets) that can be detected by the receiver. (Volume Testing & Control) Traffic Padding Principles of Information Security

9. Saad Haj Bakry, PhD, CEng, FIEE 9 Steganography (Hiding Information) Objective: To hide information within other information Examples: Message: David Owen Hidden Message: DO Watermarks bank notes / papers / Digital Watermark: Adobe PhotoShop www.adobe.com Examples: Message: David Owen Hidden Message: DO Watermarks bank notes / papers / Digital Watermark: Adobe PhotoShop www.adobe.com Solutions www.digimark.com www.conginity.com Solutions www.digimark.com www.conginity.com Proof of Ownership: Music recorded with frequencies not audible to humans Proof of Ownership: Music recorded with frequencies not audible to humans Principles of Information Security

10. Saad Haj Bakry, PhD, CEng, FIEE 10 The “Hash Function” Objective: Checking Message Integrity Hash Function Message Message Digest Mathematical Function Applied to the Message “Contents” “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 Collision: Messages with the same “hash value” Chance of Collision: Statistically insignificant Messages can be checked but not reconstructed from their hash value Principles of Information Security

11. Saad Haj Bakry, PhD, CEng, FIEE 11 Old Cryptographic Ciphers CipherAlgorithmExample Substitution Replacing “a” by “b” “b” by “c” “c” by “d”…. “information security” becomes “jogpsnbujpo tfdvsjuz” Transposition Changing the sequence of letters to become: “odd” followed by “even” “information security” becomes “ifrain-nomto scrt-euiy” Both Substitution and transposition together (see above) “information security” becomes “jgsbjo-opnup tdsu-fvjz” Principles of Information Security

12. Saad Haj Bakry, PhD, CEng, FIEE 12 Encryption: Basic Data Security Terms TermDefinition Plaintext Source text / Unencrypted data CryptographyTransforming “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 CryptanalysisBreaking / cracking encryption Principles of Information Security

13. Saad Haj Bakry, PhD, CEng, FIEE 13 Sender Secret-Key Cryptography (1) Sender Receiver Communication Network Symmetric Key Plain Text Cipher Text Encrypt / Decrypt Principles of Information Security

14. Saad Haj Bakry, PhD, CEng, FIEE 14 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” Secret-Key Cryptography (2) Principles of Information Security

15. Saad Haj Bakry, PhD, CEng, FIEE 15 P UBLIC K EY P RIVATE K EY P UBLIC K EY Asymmetric Keys Private Reception Public Transmission Man y to One Private Transmission Public Reception One to Man y Principles of Information Security

16. Saad Haj Bakry, PhD, CEng, FIEE 16 Asymmetric: Sender / Receiver Public Key: Distributed Freely Public Key: Distributed Freely Started at the MIT in 1976 by: Whitfield Diffe Martin Hellman Started at the MIT in 1976 by: Whitfield Diffe Martin Hellman Public-Key Cryptography (1/2) Private Key: Kept by the Owner Private Key: Kept by the Owner RSA P-K Algorithm: Rivest / Shamir / Adleman, MIT 1977, RSA Inc. 1982 Used by “Fortune 1000” “e-Commerce Transactions” RSA P-K Algorithm: Rivest / Shamir / Adleman, MIT 1977, RSA Inc. 1982 Used by “Fortune 1000” “e-Commerce Transactions” Principles of Information Security

17. Saad Haj Bakry, PhD, CEng, FIEE 17 Public-Key Cryptography (2/2) 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. Per Organization: One “Public Key” One“Private Key” Not One “Secret Key” per receiver. “Secret Key” Exchange Not Needed “Secret Key” Exchange Not Needed Problem: Requires high computer power / Not efficient for data volumes / Performance: Slower Principles of Information Security

18. Saad Haj Bakry, PhD, CEng, FIEE 18 Organization Public Key Organization Public Key Public-Key: Case / Problem (1) Networ k Customer Organization Organization Private Key Organization Private Key Problem: Validation of customer’s identity Principles of Information Security

19. Saad Haj Bakry, PhD, CEng, FIEE 19 Customer Private Key Customer Private Key Public-Key: Case / Problem (2) Networ k Customer Organization Customer Public Key Customer Public Key Problem: Proving the identity of the receiving organization’s Principles of Information Security

20. Saad Haj Bakry, PhD, CEng, FIEE 20 Customer Private Key Customer Private Key Public-Key: Combination / Solution Networ k Customer Organization Customer Public Key Customer Public Key Organization Public Key Organization Public Key Organization Private Key Organization Private Key Identities of both partners are authenticated Principles of Information Security

21. Saad Haj Bakry, PhD, CEng, FIEE 21 Cryptanalysis Objectives: Attack “to break key” Test “key strength” Objectives: Attack “to break key” Test “key strength” How: Analysis of encryption algorithm to find relations between “bits of encryption key” and “bits of cipher-text” in order to “determine key” Key / Cipher-text Relationship: “Statistical” nature “Plain-text” knowledge Key / Cipher-text Relationship: “Statistical” nature “Plain-text” knowledge Principles of Information Security

22. Saad Haj Bakry, PhD, CEng, FIEE 22 Error Control: against noise. Traffic padding: volume control. Steganography: hiding information. Hash Function: measure of message integrity. Cryptography: confidential information  Key: length leads to strength.  Symmetric: problems (key exchange / 1 key per receiver)  Asymmetric: problems (processing / proof of identity)  Cryptanalysis: key breaking. Remarks / Understanding Principles of Information Security

23. Saad Haj Bakry, PhD, CEng, FIEE 23 References B.R. Elbert, Private Telecommunication Networks, Artech House, US, 1989. Telecommunications Management: Network Security, The National Computer Centre Limited, UK, 1992 K.H. Rosen, Elementary Number Theory and its Applications, 4 th Edition, Addison Wesley / Longman, 1999. ISO Dictionary of Computer Science: The Standardized Vocabulary (23882), ISO, 1997. F. Botto, Dictionary of e-Business, Wiley (UK), 2000. H.M. Deitel, P.J. Deitel, K. Steinbuhler, e-Business and e-Commerce for Managers, Prentice-Hall (USA), 2001 Principles of Information Security