🚀 go-pugleaf

In article <132@vianet.UUCP> devine@vianet.UUCP (Bob Devine) writes:
>      message arrives in error, what happens?  A nasty person knowing
>      this information might be able to do a plain-text attack or 

This isn't possible for a true one-time pad system.  Crib dragging
and other favorite wedges into more traditional systems are useless
for this one.

>   2. Can just the fact that a message is sent from A to B be used to
>      suggest ssmething?

This sort of thing is the subject of a field known as "traffic
analysis", which I find rather interesting.  A good implementation
would have enough capacity for peak demands, then fill the channel
with random bits into which genuine messages would be inserted.  A
poor implementation would send messages only when there was a need
and would make their lengths obvious.  (The latter is hard to get
around, since there has to be some in-clear message header if only
for the purpose of maintaining synchronization; this argues for
a packet protocol of some sort.  Channel noise is not otherwise a
significant problem, though, since it can be dealt with by
conventional means.)

>   4. Is a different selection of random bits always used?  How is
>      the selection made?  Is the information of where to start
>      kept in a secured file?

It is essential that the bits not be re-used.  Many one-time pad
systems use different keys for different comlinks, to prevent
accidents.  Typically the message header tells the recipient which
key location to start at.  It is recommended that the used key be
destroyed as it is used.

>   5. Because the network is not secure, an active tapper could
>      interpose bad messages and delete good messages.

"Jamming" is a separate issue.  At least with this system it is
not possible to insert fake message whose decryption has any real
chance of appearing genuine, so long as there is a modest amount
of redundancy in the style of cleartext.  Truly low-redundancy
data should be given some redundancy before being encrypted.  This
and other indicators can be safely prefixed to the data, since it
isn't possible to detect them by analyzing the cipher stream.

>      a secure courier deliver the keys to the (just one?) recipient
>      is expensive because the courier must be investigated and other
>      security nonsense.

But this is just initial overhead; for an on-going operation the
high bandwidth of a courier airline bag full of optical disks is
actually very attractive from an economic standpoint.