[Cryptography] Practicality of codebook in current-day secret communications

[mok-kong shen]

Am 24.02.2016 um 23:02 schrieb Michael Kjörling:

> Why do the competitors have access to the communications in the first
> place?

Via spying somehow (should be deemed "normal" in our post-Snowdon era).

[snip]
> Remember that the idea of cryptography is to transform large secrets
> (sensitive plaintext, for some definition of sensitive) into small
> secrets (keys), because small secrets are easier to keep secret.
>
> It seems to me that surely an adversary which is able to subvert and
> monitor an active VPN link in more or less real time is quite capable
> enough to get their hands on a code book as well.

In my example the codebook has 256 entries. Is that too big for secure
keeping nowadays?

> This ties back into the above point on whether real-time communication
> is needed. Why does "essential instructions and responses" need to be
> exchanged between the negotiator and the far-away manager during
> negotiations? Why can't the negotiator have a mandate to _negotiate_,
> within some given bounds? ("Get the best offer you can, Joe, but
> whatever you do, do not accept a bid below $42 trillion.")

There are different reasons causing the representative to seek
instructions from the manager. For example, the lower limit of the
contract price originally given to the representative was dependent
on (1) assumed construction or manufacture details that could only
be exactly known by the representative at customer's site, (2)
the customer has modified the quantities of purchase in the mean
time (especially having now learnt more of the offer by the
competitors), (3) assumed product delivery time does not correspond
to what the customer currently desires (for whatever reasons) (4) the
lower limit of the contract price was actually "soft" (i.e. a highly
wished-for amount, which the manager, if hard-pressed, would eventually
yet lower a little bit), etc. etc. That a mandated representative in
negotiations has occassionally to consult his chief is to my knowledge
fairly normal in commercial practice. Analogy could also be found in
other fields IMHO, e.g. in political deals (even in daily life when
a mother sends her child to do purchasing).

[snip]

M. K. Shen