Midterm Review

Math 65S

Fall 2000

• There will be some short answer, some essay, and some math problems
• Uses of encryption
  • Confidentiality, authentication, integrity, non-repudiation
  • Medical, including HIPAA and what it requires
  • National Security: know the ``Spectrum of Intelligence'' from Privacy on the Line
  • Commerce in general: trade secrets, electronic commerce
  • Banking
  • Personal Privacy
  • Tradeoffs in choosing a system

• Math problems
  • Congruences/modular arithmetic: e.g. F8.2
  • GCD's and the Euclidean algorithm: e.g. F5.1(b), F6.1, C5.5, C5.8
  • Finding inverses: e.g. C5.6 (dividing is the same as multiplying by an inverse!)
  • Using inverses to solve equations: see affine cyphers
  • Fermat's Little Theorem: e.g. F9.1(b,c)
  • Euler's Theorem
  • Successive squaring: e.g. F16.1(b)
  • RSA: e.g. C5.9, C6.3
  • Testing for primality: e.g. F16.2
• Cyphers that you may have to decrypt
  • Additive (including Caesar): e.g. C1.4
  • Affine: e.g. C1.15
  • Know what a block cypher is but you will not have to know how Hill cyphers work
  • RSA: see above
  • Know what a One Time Pad is
• Attacking secret messages
  • Kerckhoff's Principle
  • Best to get key, second best to get plaintext
  • Letter frequency attacks
  • Types of cryptoanalytic attacks: cyphertext-only, known-plaintext, chosen-plaintext, adaptive chosen-plaintext, chosen-cyphertext, adaptive chosen-cyphertext
  • Ways around cryptography: e.g. bugs, operator error, misrepresentation, subversion, physical attack, traffic analysis, Operations INT, DOS attacks
  • Attacks on RSA: factoring (trial division, Fermat factoring, NFS); things you shouldn't do (small encryption key, small decryption key, sharing modulus, sharing encryption key, multiple messages, and so on)
  • Timing and power consumption attacks: thinking outside the box

• Public key systems
  • The difference between public-key and symmetric key systems
  • Main types of public-key systems: asymmetric keys, key agreement (a.k.a. key exchange), examples of each
  • Advantages and disadvantages of public-key systems

• Digital signatures
  • Ways to verify a person's identity: knowing, having, being, being located
  • How to use an asymmetric key system to sign and verify signatures, e.g. RSA
  • advantages and disadvantages to separate signature keys
• Patents and Export Controls
  • Why export controls
  • Why not export controls
  • Current rules in the US
  • Why patents
  • Why not patents
  • The RSA patent

About this document ...

Midterm Review

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