PKI Implementation

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PKI Implementation
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PKI Implementation

• User names and PKI
• Trust
• Authorization
• Revocation
• Keys and PKI

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User names and PKI

• PKI does not attempt to associate username with a
  unique individual
• Only choice available is the email or screen name
  for identification
• One individual may have multiple email / screen
  names
• Government issued identities such as Social
  Security Number are restricted in usage

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User names and PKI

• Certificate Authority assigns unique names
• CA also provides verification

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Trust

• PKI enables key management for cryptography
• PKI relies on the trustworthiness of the CA
• Cryptography emphasizes trust for key exchange

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Authorization

• Currently users are given userIDs and a separate
  method of assigning access privileges controls
  permissions
• One way to control permissions is via Access
  Control Lists (ACL)
• ACL is a database table and consequently could be
  the target of an attack
• Direct authorization means userIDs are given the
  necessary privileges

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Authorization

• Credentialing is another way to provide
  authorization
• Credentialing enables time-based authorization
• Credentialing could be cumbersome in online
  validation of certificates

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Revocation

• CA revokes certificates based on
• User request (possibly lost key)
• Failure to follow policies
• Employee left the organization
• Users should be educated to check for revocation
• Revocation involves
• Reliability
• Speed
• Revocation system should be dynamic

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Revocation

• Certificate Revocation List (CRL) should be
  accessible by all users
• Lack of a universal CA limits the use of CRL
• Central CRL (such as the central pool of
  toll-free numbers) could facilitate CRL use
• Preferred solution is a distributed CRL system
• Alternative to revocation is fast expiration such
  as certificates that expire in 10 minutes

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Keys and PKI

• Key server could perform the role of PKI
• Key server has some disadvantages
• Key server must be available all the time for
  validation
• PKI, because of CRL and expiration, does not have
  to be available all the time
• Key server is centralized by its very nature
• PKI uses certificates used by CAs by other
  validation means

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Keys and PKI

• PKI provides non-repudiation
• The root key of CA need not be online for
  authentication or verification
• PKI is more complex than a key server system
• Key servers are well suited for small systems
• PKI is well suited for large systems

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Keys and PKI

• http//www.cs.auckland.ac.nz/pgut001/pubs/x509gui
  de.txt
• For PKI to work efficiently we may need something
  like XML to interpret data
• XML allows multiple representations of data to
  bring to the web
• CA should be able to use a language that the
  sub-CAs understand and which is present in the
  certificate

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Keys and PKI

• Alice generates the public/private key and shares
  the public key with the CA who validates Alice
• CA distributes the public key
• Keys should have a passive use time with
  reference to expiration of key