Cryptography's Role in Networking
"Cryptography is the science of making the cost of improperly
acquiring or altering data greater than the potential value gained.
The value of information usually drops with time, and cryptography
makes the time required to obtain data in unauthorized ways long
enough to decrease its value well below the money spent on obtaining
it."
Jalah Feghhi, Digital Certificates
|
The need for cryptography to provide security arises with the possibility of
stolen hardware,
wiretapping,
the broadcast mechanisms of LANs and WLANs,
and network traffic passing through foreign networks.
We assume that an adversary is able to :
- Copy data from disk storage for remote analysis,
- Passively listen (only) on broadcast channels
(such as wired-Ethernet and WiFi),
- Aggressively monitor traffic though intermediate routers or
workstations (situated anywhere on a message's path),
- Actively replay, modify or insert their own messages into the
message stream.
Cryptography provides solutions to most of these problems.
So where should the encryption be performed?
- Users encrypting individual files stored in a standard file-system,
- File-systems encrypting all data before writing it to disk,
- Datalink and Network layers: in switches and routers (e.g. VPNs),
- Session Layer: with end-to-end data conversion (e.g. SSL),
- Application Layer: in programs such as email agents (e.g. PGP).
CITS3002 Computer Networks, Lecture 12, Cryptography's role in networking, p2, 22nd May 2024.
|
CITS3002