[Cryptography] Auditing rngs

[lists at notatla.org.uk]

ianG <iang iang.org> writes:

> That is the general concept, the HSM is for public key operations on a
> high value key-pair.  But it is harder to implement than it is to sell.
> There are these difficulties that I've come across (and I'm no more
> than a skeptical observer):
> 
> a.  the interface requires pretty tight software to drive it, and
> especially for low-frequency, high-value operations such as root key
> creation, there can be a mismatch between the quality of the software
> and the importance of the task.

- The installation instructions might not work.
- The claimed compatibility between the cert manager
  and a certain HSM might not exist (till updates fix that).
- Multiple s/w updates might be needed to overcome crashes.
- The vendor might claim your configuration is unsupported
  when you've followed their advice in setting it up.
- The vendor may appear to have few people skilled in the product.

> b.  backups!  Once these high value keys are created, there needs to be
> a process to recover.  Lost/broken HSMs?  No problems, we'll just buy 3
> instead of 1.  Ah, now, how do we get the high value key from HSM 1 to
> HSM 2 ... which has to be done before hand....  HSMs have this ability
> but it's also fraught as above.

You can get continual replication between a set of compatible HSMs in
different locations.

> d.  Something goes wrong ... and we don't have the skills to figure it
> out.  Only the purchased software can drive the HSM, and that's too hard
> to figure out.  The people who set it all up are long gone, the company
> who sold the HSM is sold to another and the salesman wants to solve your
> problem by selling you another better type.  Problems of this nature are
> things like serial numbers changing, variations in the HSMs, batteries
> going flat coz they sat on the shelf for 5 years, water damage, fans
> gumming up, host hardware needing to change and having incompatible
> specs, even the size of the new machine can impact, etc etc.

With HSMs on USB or ethernet changing the host hardware is only like
replacing any other server plus data.