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Security Metadata

COMP315 Lectures

Network Topology

Direct Connection

The simplest network is a direct connection between two peers that wish to communicate.

This doesn’t scale well and is costly. For $x$ nodes there will be:

\[\frac{x(x-1)}{2}\]

connections.

They are useful if you require:

  • Extreme Speed
  • Extreme Secrecy
  • Extreme Bandwidth

Star Topology

graph TD
1 --- n
2 --- n
3 --- n
4 --- n
5 --- n
6 --- n
7 --- n
8 --- n
9 --- n

All nodes connect to a central hub that distributes communications. This scales better but can be easily overwhelmed due to the single point of failure.

Tree

This is a collection of sub-networks that are joined by a central hub. This helps for communicating between neighbours quicker.

Mesh

This is a messy topology that has a number of connections between leaves. Generally the number of connections required is:

\[x-1\]

For a more stable network, the following number of connections is suggested:

\[x\log(x)\]

Internet Topology

There are a number of tiers with progressively reduced nodes. There are links between nodes in the same tiers and their children.

This is bad from a security standpoint as your message may have to travel through several third parties.

Layers

Refer to:

for the protocol layer structure.

Metadata

HTTPS Metadata

For HTTPS over TCP over IP, the following is leaked:

  • IP Addresses and ports of the sender & receiver.
  • Target domain name.
  • Size and time of the transfer.
  • Information about the type of encryption used and certificates.

Email Metadata

Only the body of an encrypted, with PGP, from the email server. In flight the email is encrypted using TLS. Thus, the following are leaked:

  • Message time and size.
  • Sender
  • Receiver
  • Subject

Sender and receiver could be hidden by using a service such as TOR.

Metadata Mitigation

We kill people based on metadata. - Michael Hayden (CIA, NSA Former Director)