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Pretty good privacy

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Description of basic workings of PGP

Description of basic workings of PGP

Published in: Technology

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Transcript

  • 1. pretty good privacy
    securing e-mail communication
    5.5.2010
  • 2. THE PROBLEM
    e-mail „security“
    5.5.2010
    Pretty good privacy
    2
  • 3. SMTP protocol
    5.5.2010
    3
    S: 220 smtp.example.com ESMTP Postfix
    C: HELO relay.example.org
    S: 250 Hello relay.example.org, I am glad to meet you
    C: MAIL FROM:<bob@example.org>
    S: 250 Ok
    C: RCPT TO:<alice@example.com>
    S: 250 Ok
    C: RCPT TO:<theboss@example.com>
    S: 250 Ok
    C: DATA
    S: 354 End data with <CR><LF>.<CR><LF>
    C: Hello Alice.
    C: Your friend, Bob
    C: .
    S: 250 Ok: queued as 12345
    C: QUIT
    S: 221 Bye
    Pretty good privacy
  • 4. SMTP protocol
    4
    PLAIN TEXT
    everyone on the way can read it
    Pretty good privacy
    5.5.2010
  • 5. SMTP protocol
    Pretty good privacy
    5
    NO AUTHENTICATION
    everyone can pose as everyone
    5.5.2010
  • 6. SMTP protocol
    Pretty good privacy
    6
    SIZE LIMIT
    e-mails are limited in size
    5.5.2010
  • 7. THE SOLUTION
    PGP - open solution to our problems
    5.5.2010
    Pretty good privacy
    7
  • 8. PGP features
    Authentication
    Confidentiality
    Compression
    Segmentation
    8
    5.5.2010
    Pretty good privacy
  • 9. Predicates
    Asymetric encryption
    Digest algorithm
    9
    Private/public key pair
    Private key is secret and uncompromised
    Private key encrypted data can only be decrypted by corresponding public key
    Reverse holds true as well
    Same input always generates same output
    Small change of input causes huge change on output
    Chance of collision has to be minimal
    5.5.2010
    Pretty good privacy
  • 10. Authentication
    10
    confirming the sender‘s identity
    MATCH?
    SHA-1digest
    SHA-1digest
    Sender‘s public key
    RSAencryption
    RSAdecryption
    Sender‘s private key
    5.5.2010
    Pretty good privacy
  • 11. Encryption
    11
    confirming the sender‘s identitymaking sure noone else can read the message
    IDEAencryption
    Session key
    IDEAencryption
    Recipient‘s public
    key
    5.5.2010
    Pretty good privacy
  • 12. Decryption
    12
    confirming the sender‘s identitymaking sure noone else can read the message
    IDEAdecryption
    IDEAdecryption
    Session key
    Recipient‘s private
    key
    5.5.2010
    Pretty good privacy
  • 13. Decryption
    13
    saving bandwidthincreasing cryptoanalysis resistance
    Sender
    Recipient
    5.5.2010
    Pretty good privacy
  • 14. Compatibility & segmentation
    14
    traveling across platformsavoiding maximum size limit
    Compatibility
    +33% size
    radix-64
    binary data
    Segmentation
    automatic segmentation and reassembly of long messages
    5.5.2010
    Pretty good privacy
  • 15. THE CONCLUSION
    Jernej Virag
    15
    5.5.2010
    Pretty good privacy