Paper #:[4.3 Security] #13
Title: "The Sybil Attack" by John R. Douceur

PROBLEM
In order to ensure that data is available on peer-to-peer systems, redundancy is
used.  However, if an entity pretends to represent multiple entities, and that
entity goes down then the data may be lost.  Consequently a need exists for a
trusted and central authority to ensure that there is a 1:1 entity to identity
relationship.  Therefore, the author wants to prevent the problem of one entity
masquerading as multiple entities, which is the result of Sybil attacks.

NEW IDEAS AND STRENGTHS
*The paper brings up a good point that a voucher system can be undermined when a
Sybil attack occurs because the local entity doesn't know who it can trust.
*It is a good idea to give two entities a task that a single entity can't perform
in order to sniff out fake entities.  One of the best ways to do this is through
the use of puzzles.
*In addition, the solution takes into considerations that some entities may get by
the initial test; consequently, they are constantly tested to ensure that initial
misses are caught.

WEAKNESSES AND EXTENSIONS
While it is a good idea to give two entities a single test that a single entity
would not be able to handle, this may prevent weaker entities from being included.
Due to Moore's law, processor speed continues to double at a fast pace.
Consequently, someone with a 3Ghz machine can do a lot more computation than
someone with a 120Mhz machine.