Lecture

Cryptography and Computer Network Security

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BASIC CONCEPTS
CLASSICAL CRYPTOALGORITHMS
PUBLIC KEY CRYPTOALGORITHMS
SECURITY SERVICES
KEY MANAGEMENT
CRYPTOGRAPHIC STANDARDS AND SECURE INTERNET PROTOCOLS

Additional topics (discussed if the time permits)

KEY ESCROW SCHEMES - CRYPTOGRAPHY AND LAW ENFORCEMENT
QUANTUM CRYPTOGRAPHY AND QUANTUM COMPUTING


BASIC CONCEPTS


  1. The need for security services in today's computer networks
    Threats to computer security.
    Security services in computer networks and relationships among them:
    confidentiality, integrity, authentication, non-repudiation
    identification, access control, auditing.
    Electronic commerce and other applications of security services in today's computer networks.
    Survey of domestic and foreign cryptographic products.
    Shamir's "ten commandments" of commercial security.

  2. Basic concepts of cryptology
    Cryptosystem, plaintext, ciphertext, key.
    Examples of simple cryptosystems.
    To publish or not to publish?
    Secret and open research in cryptology.
    Software vs. hardware implementations of cryptography.
    Evolution of cryptography and cryptanalysis.

  3. Types of cryptosystems. Implementation of security services
    Classical (symmetric) vs. public key (asymmetric) cryptosystems.
    Trapdoor one-way functions - main components of public key cryptosystems.
    Features required from today's ciphers.
    Implementing security services using cryptographic transformations.
    Block vs. stream ciphers.
    Measures of the cipher strength.

    4.  

    CLASSICAL CRYPTOALGORITHMS


  4. Historical ciphers
    Substitution ciphers
    monoalphabetic
    polyalphabetic
    running-key
    polygram
    homophonic
    Transposition ciphers.
    Breaking ciphers using frequency analysis.
    Shannon's theory of perfect secrecy and its practical implications. One-time pad.
    Product ciphers.

  5. Data Encryption Standard - first attempt to standardize protection of information in public computer networks
    History of the cryptosystem - the NBS-NSA-IBM roles.
    Acceptance by government and commercial sectors.
    Main features of the algorithm.
    Design criteria.
    Differential and linear cryptanalysis.
    Vulnerability to the exhaustive key search attack
    Triple DES.
    Modes of operation.
    Security of different operational modes.

  6. Other symmetric-key block ciphers
    IDEA, RC5, Blowfish, DESX, Skipjack.
    Fast software encryption cryptoalgorithms.
    Minimal key lengths for symmetric-key ciphers.

  7. Implementing secret-key block ciphers
    8. General software and hardware architectures.
    Implementing basic component operations in software and hardware.
    Fast hardware architectures
    loop unrolling
    inner-round pipelining
    outer-round pipelining
    mixed inner- and outer-round pipelining
    Limitations imposed by various implementation environments.

  8. Development of the new Advanced Encryption Standard - AES
    9. Rules of the contest
    Evaluation criteria
    AES candidate algorithms
    Comparing AES candidates
    Security
    Efficiency in software
    Efficiency in hardware
    Flexibility
    Evaluation process

     

    PUBLIC KEY CRYPTOALGORITHMS


  9. RSA (Rivest, Shamir, Adleman) cryptosystem - first successful public key cryptosystem
    Genesis of RSA.
    RSA as a trapdoor one-way function.
    Factorization as a basis of the RSA security
    factorization records
    factoring big numbers using a distributed network of computers
    RSA challenges
    Recommended key sizes for the RSA cryptosystem.

  10. Key generation in the RSA cryptosystem
    11. General purpose vs. special purpose factoring algorithms.
    RSA for paranoids.
    Strong primes
    Probabilistic tests for primality.
    Deterministic tests for primality.
    Constructing large random primes.

  11. Format of the RSA messages - secure padding
    12. recovering RSA-encrypted messages without the knowledge of the private key.
    PKCS v. 1.5 padding for encryption.
    Bleichenbacher's attack
    Optimal Assymetric Encryption Padding.

  12. Implementing public-key ciphers
    Basic exponentiation algorithm.
    Using Chinese Remainder Theorem for fast exponentiation.
    Basic algorithms for multiplication and modular reduction in software.
    Basic architectures for multiplication and modular reduction in hardware.
    Dependence between the key size and the times of cryptographic transformations.
    Survey of existing RSA implementations.

     

    13. SECURITY SERVICES


  13. Digital signatures. Digital Signature Standard
    Classification of digital signatures.
    Attacks against digital signatures.
    Secure padding for signatures.
    Digital Signature Standard (DSS).
    Comparative analysis of RSA and DSS - security, performance, functionality.
    Legal issues concerning digital signatures - Utah Digital Signature Act, California signature law, legislation in other states.
     
  14. Data integrity and authentication - two faces of the same problem. Hash functions and MACs
    Requirements for secure hash functions.
    Classification of hash functions.
    Attacks against hash functions.
    Standard and non-standard applications of hash functions.
    digital signatures and authentication codes
    virus detection
    password storage
    fast encryption
    Families of hash function algorithms and their security
    Requirements for Message Authentication Code (MAC).
    Families of MACs and their security.
    Authentication combined with confidentiality.

    15. KEY MANAGEMENT


  15. Exchange of keys for symmetric-key cryptosystems
    Session keys and key encrypting keys.
    Exchange of keys using Key Distribution Center.
    The Diffie-Hellman key exchange protocol.
    Exchange of symmetric keys using public key cryptosystems.

  16. Public key certificates (digital IDs) and infrastructure of Certification Authorities
    Generation and registration of the public key pair.
    Concept of a public key certificate.
    Formats of certificates (X.509, EDIFACT, etc.).
    Hierarchy of Certification Authorities - Public Key Infrastructure.
    Certificate revocation.

    17. CRYPTOGRAPHIC STANDARDS AND SECURE INTERNET PROTOCOLS

     

  17. American and international cryptographic standards
    Standard organizations.
    Main groups of cryptographic standards:
    federal standards
    ANSI standards
    IEEE standards
    ISO standards
    informal industry standards.
    Classical cryptography standards.
    Public-key cryptography standards.

  18. Secure Internet Protocols
    Secure electronic mail
    S/MIME
    Open PGP
    Secure WWW
    SSL
    S-HTTP
    Secure payment card protocols
    SET
    electronic cash
    micropayments
    Secure virtual private networks
    IPSec
    PPTP

  19. Export and import control of cryptographic devices
    Evolution of the U.S. policy.
    Current U.S. regulations.

    20.  

    Additional topics (discussed if the time permits)


    KEY ESCROW SCHEMES - CRYPTOGRAPHY AND LAW ENFORCEMENT


  20. Clipper Chip and alternative key escrow systems
    Genesis of the idea.
    Clipper procedure for the law-enforced wiretapping.
    Skipjack algorithm. Clipper protocol and key generation procedure.
    Blaze's attack.
    Alternatives to the Clipper chip:
    Micali's fair public key cryptosystems.
    Other key-escrow schemes.
    Discussion - Is the enforced by law wiretapping a good way to protect society from criminals?

    21.  

    QUANTUM CRYPTOGRAPHY AND QUANTUM COMPUTING


  21. Quantum cryptography - cryptography of the XXI century?
    Basic concept of quantum cryptography - Heisenberg principle translated into an ideal security.
    First practical implementations of quantum cryptography - performance, cost, current constraints.
    Towards a quantum computer.
    Breaking ciphers using quantum computers - dream or reality?
    Will physics replace mathematics as a basis for computer-network security?
    Current research trends in cryptology and computer-network security.