VM: Security: Prevent DoS from hashmap collisions

[kevmoo]

See https://code.google.com/p/dart/issues/detail?id=1748

This is for tracking the VM implementation of hashing algorithms

[kevmoo]

Marked this as blocking #1748.

[kodandersson]

Set owner to @kodandersson.

[kodandersson]

This very old feature request should have a priority assigned to it. How important is this relative to other DoS vectors, and how much performance are we willing to sacrifice?

[kevmoo]

I'd have to see a stack-rank of DOS vectors. 😄

How much performance: enough to mitigate the concern. Given ruby, JS, .NET etc have handled this, I'm assuming there are ways to do it without causing big regressions.

[DemiMarie]

SipHash is a fast, cryptographically secure hash function.

Another option is to use trees instead of linked list to back the buckets.