Categories
Data Communications

FIT9020: Week 4

The Data link Layer was covered in week 4 of Data communications, which was another high detail lecture [All Trains Now Depart Promptly -> Application, Transport, Network, Data Link, Physical] .

Using both Logical Link Control [LLC] and Media Access Control [MAC] the Data Link layer controls when computers transmit data, detects and correct transmission errors and identifies the beginning and end of messages.

Reminder, half duplex is one message at a time, full duplex (enabled by co-axial cables) message can pass each other.
Categories
Grid Computing

FIT5164: Week 4

Grid Computing’s week 4 lecture took a security theme covering the Grid Security Infrastructure [GSI], Public key infrastructure , Digital certificates, Mutual authentication, My Proxy and shibboleth.

GSI (see: http://en.wikipedia.org/wiki/Grid_Security_Infrastructure) is an overlay on the transport security protocol (SSL) utilizing asymmetric encryption and the public key infrastructure to acheive:

  • Authentication
  • Data integrity verification
  • Single sign-on
  • Inter-organisation decentralized security

All grid entities (user and processes) must have a public key certificate, for more info on public key certificates see: http://en.wikipedia.org/wiki/Public_key_certificate

GSI uses the X.509 standard which included 4 primary pieces of information:

  • subject name
  • public key
  • identity
  • digital signature

An illustration of the public key infrastructure process:

source: week 4 lecture notes

Scenario 1 -> privacy, only user can decrypt incoming data

Scenario 2 -> authentication, receivers decrypt data using the sources public key this ensures the data is coming from the correct source

Certificate authorities are required to ensure validity of public and private keys that make the users digital certificate