Encryption, Part II Public Key Infrastructure

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Encryption, Part II Public Key Infrastructure

• Presented by Richard Stiennon
• Founder IT-Harvest

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Your Speaker

• Richard Stiennon
• richard_at_it-harvest.com
• www.threatchaos.com

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This Weeks Exciting Agenda

• Day 1 Encryption Basics
• Day 2 Public Key Infrastructure
• Day 3 Beyond PKI Making Encryption Useable
• Day 4 Digital Money We Can Do It
• Day 5 Trusted Computing
  Disappointment Promise

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Refresher

• Block cyphers
• Plain text 0011011010001
• Key 1110100011101
• Cyphertext 1101111001100
• Keeping decryption keys secret
• Shared keys

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Principal of Good Crytpo

• Algorithm is public
• Keys are secret

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Data Encryption Standard (DES)

• 16 repetitions of a block cypher
• Invented by IBM in 1976
• Symmetric shared key

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Whitfield Diffie Hellman

• Answers the question Howcan I send a key in
  the clear?
• Alice sends ga mod p to BobBob sends gb mod p
  to Alice
• (ga)b mod p (gb)a mod p secret key!
• Note p, a, and b, are REALY BIG g 2 or 5
  usually

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RSA Rivest, Shamir, Adleman

• First describe in 1978
• Allows for signing as well as key exchange
• Relies on one-way function
• Difficulty of factoring large multiple of two
  LARGE numbers

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Taher Elgamal SSL(TLS)

• 1995 Netscape
• Enables e-commerce
• Usually authenticates
• Server only
• Flexible algorithms (usually RSA)

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Key Length Is Key
Encryption is only as good as key length. Its a
matter of economics.
Tomorrow Key management is key