Data transmission (networking & cryptography) Flashcards
circuit-switching
establishes end-to-end connection at a fixed rate
packet-switching
many nodes inter-connected (e.g. internet) - traffic forwarded from one node to another until it reaches its destination
network protocol definition
rules to govern syntax and synchronization of communication
Protocol Data Unit (PDU) format
type | dest. add. | source add. | length | payload | error checking
OSI model layers
bottom -> top physical link network transport session presentation application
physical layer (OSI)
data encoding: how does receiver interpret frame? physical pins (which and what do they represent) Vin, digital/analog transmission
network layer
routing (routes frames across network)
subnet traffic control
logical/physical address mapping
builds headers
transport layer
ensures messages are delivered error free, in sequence, no loss (TCP)
session layer
allows two application processes on different machines to establish/use/end a session
presentation layer
“translator” of network layer and formats data to be displayed on application layer
data conversion, compression, encryption
application layer
FTP, IM, mail, printers
public-key authentication
two keys generated: both generate public keys, and Joe generates private key known only to Jill. To encrypt/deceypt, must use public key + private key.
internet model
bottom-top:
physical
network interface (MAC, ethernet, wifi)
network layer (routing, IP)
transport layer (host-host comms, UDP, TCP)
application layer (software comms, HTTP, DNS)
hash algorithm (concept)
produces short number from message of arbitrary length. Doesn’t operate in reverse.
authorization vs. authentication
authorization: enforces access rights to users, whereas authentication: verifies the message sender
