On Tuesday, January 22, 2019, 3:13:07 PM PST, Steve Kinney
   <admin@pilobilus.net> wrote:

   On 1/13/19 10:43 PM, Mirimir wrote:
   >> Dropgangs, or the future of dark markets
   >Here's some ideas about structural vulnerabilities in the Dropgang
   protocol, as described at [1]https://opaque.link/post/dropgang/
   >Dead drop reuse:
   >To achieve acceptable security each dead drop may be used once only,
   because hostile buyers could place 'their' dead drops under video
   surveillance  and record every courier and customer visit to the drop
   following their own transaction.
   >Couriers delivering to dead drops can not determine if their supplier
   sends them to previously used dead drops, unless they service only dead
   drops they set up and document themselves.  Couriers should transmit
   the
   locations of drops they have developed only when presented with an
   order
   to fill, to assure that their distributor can not send other couriers
   and customers to use them first.  The added surveillance exposure of
   making two visits to the same site - setup and delivery - presents less
   exposure than trusting that the anonymous seller will never send a
   courier to a previously used dead drop.
   [much stuff deleted]
   People who think of a 'dead drop' as being a previously-existing
   hidey-hole in the urban/suburban landscape need to remember that even
   if they are relatively plentiful, they are NOT so plentiful that they
   won't be reused at some point.  Or much more likely, probed on
   speculation by passers-by, especially once they learn that such
   locations may be used as dead-drops.
   This is one reason I previously described my idea to have a pointy
   metal or stiff-plastic  tube driven into the soil or  in grassy area,
   maybe 1 inch in diameter, and then filled with a removable tube with
   the payload contained in it.  For an approximate shape, take a look at
   this ad for centrifuge tube:
   [2]https://www.usplastic.com/catalog/item.aspx?sku=76941&gclid=Cj0KCQiA
   m5viBRD4ARIsADGUT24x7cDtbtnGyiwG2_DKaCKpwCn9I-jw8XHCOwL17U0LCWFB3SQkyGA
   aArjUEALw_wcB
   (BUTTON)
   (Although I am not suggesting employing an actual 'centrifuge tube':
   They appear to be much too expensive for this purpose.  I am merely
   showing the approximate simple shape that could be employed.)
   Its location, when placed, is essentially arbitrary.   All cities,
   suburbs, and towns, to say nothing of rural areas, are quite full of
   parks, fields, unbuilt lots, golf courses, cemeteries, grassy medians,
   high-tension line rights-of-way, gravel roads, beaches, and forested
   areas.  Almost all of that could be employed to hide a tiny pipe whose
   presence would probably go unnoticed for years, and certainly for hours
   and days.
   The main requirement to find the store is a precise GPS system, ideally
   one which can employ WAAS (Wide Area Augmentation System), which
   usually will provide a location accuracy of 1 meters.  That alone would
   probably be sufficient.
   If people are assumed to only have access to ordinary GPS receivers,
   such as those in smartphones, I have also suggested using a plastic
   molded "corner-cube" retroreflection device to accurately send back
   light (or, with an IR-only filter, IR) to the searcher.  See Acrylite
   GP color
   1146-0.  [3]https://www.eplastics.com/plexiglass/acrylic-sheets/ir-tran
   smitting   This material can be placed over an ordinary clear-plastic
   retroreflector, and according to the graph shown it retroreflects only
   1% of 1% (or 0.01%; it loses 99% on each pass through the sheet.)   The
   retroreflection plane can be 'aimed' in a specific direction, to make
   it even more unlikely to be accidentally found by a random passer-by.
   Another aid to finding such a cache would be to throw a few hundreds or
   thousands of tiny (say, 1/100 inch diameter? polished glass beads,
   around the target, after it was placed in a grassy area.  These glass
   beads would, themselves, be somewhat retroreflective, but could only be
   seen from above as the searcher gets close to the cache.  Or, a small
   retroreflection disk can be placed, face-up, at or near the cache.
                    Jim Bell

References

   1. https://opaque.link/post/dropgang/
   2. https://www.usplastic.com/catalog/item.aspx?sku=76941&gclid=Cj0KCQiAm5viBRD4ARIsADGUT24x7cDtbtnGyiwG2_DKaCKpwCn9I-jw8XHCOwL17U0LCWFB3SQkyGAaArjUEALw_wcB
   3. https://www.eplastics.com/plexiglass/acrylic-sheets/ir-transmitting