Ensuring trust for non-Helium hotspots (HIP draft, DIY gateways)

0009-non-helium-hotspots.md

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+- Start Date: 02/19/2020
+- HIP PR:
+- Tracking Issue:
+
+# Summary
+[summary]: #summary
+
+A comprehensive set of improvements to Proof-of-Coverage, the scoring system, how Hotspots join the network, and
+participate in mining and the HBBFT consensus group.
+
+# Motivation
+[motivation]: #motivation
+
+On the Helium network today, only Hotspot hardware purchased from Helium Inc. is considered trustworthy. These Hotspots
+are sold using a hardware key storage device (a secure element) that makes it reasonably challenging for an attacker to
+create a virtual network of Hotspots that have valid keys. The downside of this situation is that the tens of thousands
+of non-Helium Inc. LoRa gateways that exist in the world cannot join the network and participate in mining.
+
+The goal of this proposal is to propose a set of measures that make it safe for LoRa gateways of unknown origin to
+participate in Proofs-of-Coverage and earn tokens for that participation. This goal poses some interesting challenges,
+as in the current system the network loses the ability to verifiably prove that any sub-network created by such new
+gateways truly exists since it's possible for dishonest actors to fake geographic locations and radio activitity.
+
+# Stakeholders
+[stakeholders]: #stakeholders
+
+- 3rd party Hotspot manufacturers
+- DIY miners
+
+# Problem Definition
+[problem-definition]: #problem-definition
+
+There are a number of problems we hope to address with this proposal:
+
+1. Allow non-Helium Inc manufactured Hotspots to participate in Proof-of-Coverage and mining
+2. Provide a way for non-radio hardware to participate in consensus groups
+3. Increase the requirements for consensus group participation to improve the overall health of the network
+4. Introduce a number of penalties for failing to perform any of the roles required for earning HNT
+
+# Allowing non-Helium Inc manufactured Hotspots to participate in Proof-of-Coverage
+[non-helium-hotspots]: #non-helium-hotspots
+
+## The problem
+
+Consider the below network where Hotspots A through F are of unknown origin, with the lines representing reported RF
+connectivity between hotspots.
+
+                     +------+
+                     |      |
+         +-----------+  A   |
+         |           |      |
+         |           +------+
+         |
+    +------+
+    |      |
+    |  F   |
+    |      |
+    +------+
+        |            +------+
+        |            |      |
+        |            |  B   |
+        |            |      |
+        |            +------+            +------+
+    +------+             |               |      |
+    |      |             |               |  C   |
+    |  E   +-----------------------------+      |
+    |      |             |               +------+
+    +------+             |
+        |                |
+        |             +------+
+        |             |      |
+        +-------------+  D   |
+                      |      |
+                      +------+
+
+Since it is possible for RF data to be fabricated - there is no way to verify that data was sent via RF once it has been
+demodulated - the network does not know whether these Hotspots are part of a virtual network, or whether they are
+physically deployed at their claimed locations.
+
+To correctly identify whether the above network is legitimate, we can introduce a Helium Inc (or authorized 3rd party
+reseller) 'trusted' Hotspot into the network and learn more about the behavior of the Hotspots A-F. Only real Hotspots
+will be able to successfully participate in PoC challenges involving the trusted Hotspot.
+
+Reimagining the above network with the introduction of a trusted Hotspot, consider the below:
+
+                     +------+
+                     |      |
+                     |  A   +---------------+
+                     |      |               |
+                     +------+               |
+                                         +--+---+
+    +------+                             |      |
+    |      |                             |  X   +<--+ Trusted Hotspot
+    |  F   |             +---------------+      |
+    |      |             |               +------+
+    +------+             |
+                     +---+--+
+                     |      |
+                     |  B   |
+                     |      |
+                     +---+--+            +------+
+    +------+             |               |      |
+    |      |             |               |  C   |
+    |  E   |             |               |      |
+    |      |             |               +------+
+    +---+--+             |
+        |                |
+        |             +--+---+
+        |             |      |
+        +-------------+  D   |
+                      |      |
+                      +------+
+
+With this information, we can verify that A, B, D and E can successfully complete PoC challenges which involve X. Since
+we know that Hotspot X is trustworthy, we can conclude that any Hotspot which can participate in a PoC challenge
+involving X can only do so if it's operating within the rules set by the consensus mechanism and also has an operating
+radio chip.
+
+However, even with this scheme we still need a way to allow Hotspots not manufactured by Helium Inc or authorized
+manufacturers to not only participate in PoC but also be candidates for consensus membership.
+
+To counter that and allow any hotspot to participate in PoC and have consensus membership candidacy, we propose to
+introduce "Levels of Trust".
+
+## Current Network Behavior
+
+In the current network, onboarding a Helium Inc manufactured Hotspot grants full Proof-of-Coverage priviledges. 
+
+As mentioned in the problem defintion, we cannot assume that every single DIY hotspot is going to incorporate a GPS chip
+or a radio chip.  Malicious enttities may try to game the system by tweaking/removing hardware and yet be able to
+participate in PoC. Currently we _know_ that every single hotspot being added to the network is manufactured by helium
+and has the required hardware to participate in proof-of-coverage challenges, as soon as we allow other hotspots to join
+the network we have no verifiable way of being able to separate a virtual network from a real one.
+
+To mitigate that, we propose a new model for establishing trust among hotspots and subsequently change how hotspots earn
+HNT, named "Levels of Trust".
+
+## Levels of Trust
+
+Below is a visual representation of the aforementioned Levels, the most important takeaway here is that any higher Level
+encompasses all the benefits and constraints of the lower Levels (with a few exceptions).
+
+
+                                                        +------------+
+                                                        |            |
+                                                +------>+  Level 3A  +---------+
+                                                |       |            |         |
+    +-----------+         +-----------+         |       +------------+         |         +-----------+
+    |           |         |           |         |                              |         |           |
+    |  Level 1  +-------->+  Level 2  +-------->+                              +-------->+  Level 4  |
+    |           |         |           |         |                              |         |           |
+    +-----+-----+         +-----------+         |       +------------+         |         +-----------+
+          |                                     |       |            |         |
+          |                                     +------>+  Level 3B  +---------+
+          |                                             |            |
+          |                                             +------+-----+
+          |                                                    ^
+          |                                                    |
+          |                                                    |
+          +----------------------------------------------------+
+
+
+Before we get into the details and constraints of each level, we need to set some common ground:
+
+* Every hotspot joining the network starts at the first level.
+* Every successive level is granted the priviledges of all previous levels.
+* Organic network growth allows hotspots to get to level 3A. In order to reach level 4, the owner must stake HNT.
+* There is a path to get to level 3B from level 1 via on-chain governance mechanism (TBD).
+
+### Level I: Getting on the network
+
+- Every hotspot which joins the helium network starts at Level 1 by issuing an `add_gateway` transaction.
+- The entry fee is set to burning data credits worth $10 USD.
+- A hotspot at Level 1 does not have any location asserted on the network, however, it is allowed to witness nearby PoC
+  challenges. This is to ensure that when the hotspot does assert a location via `assert_location` transaction, we can
+  be confident about its claim of location by analyzing its witness list.
+- A hotspot at Level 1 is allowed to transmit data and earn HNT based only on transmitting network data.
+
+### Level 2: Asserting location on the network
+
+- A hotspot must satisfy the below minimum criteria to enter Level 2:
+    * It must be a Level 1 hotspot for X number of blocks.
+    * Issue an `assert_location` transaction by incurring a $40 USD data credit burn fee.
+    * Witness sufficient number of PoC challenges involving Level 3 and above hotspots.
+- A hotspot at Level 2 gains access to participate in PoC challenges (become a member in the PoC path).
+
+### Level 3: Gaining PoC challenge priviledges
+
+Level 3 is divided into two broad categories:
+
+#### Level 3A: Organic network growth
+
+- A hotspot must satisfy the below minimum criteria to enter Level 3A:
+    * It must be a Level 2 hotspot for X number of blocks.
+    * Successfully participate in X number of PoC challenges involving other Level 3 and above hotspots.
+    * A successful challenge comprises of the hotspot being able to receive a PoC packet from a Level 3 hotspot,
+      successfully decrypt it and successfully transmit it to a Level 2 or above hotspot.
+- A hotspot at Level 3A gains access to construct PoC challenges.
+
+#### Level 3B: On-chain governance
+
+- A hotspot must satisfy the below minimum criteria to enter Level 3B:
+    * It must be a Level 1 hotspot for X number of blocks.
+    * It must be voted in via the on-chain governance mechanism (TBD) wherein either Helium (or an authorized 3rd party)
+      countersigns the `assert_location` transaction on the hotspot owner's behalf.
+- A hotspot at Level 3B gains access to construct PoC challenges.
+
+### Level 4: Consensus candidacy
+
+- A hotspot must satisfy the below minimum criteria to enter Level 4:
+    * It must be a Level 3 hotspot for X number of blocks.
+    * The hotspot owner or another miner in the network must stake 10000 HNT in order to claim Level 4 status for the
+      hotspot.
+- A hotspot at Level 4 gains access to consensus membership candidacy.
+
+## Level Demotion
+
+With the exception of Level 3B and Level 4 hotspots, any hotspot belonging to other levels is susceptible to level
+demotion governed by the hotspot's score. If the score for a hotspot drops by X for Y blocks, it will be demoted down to
+one previous level.
+
+# Drawbacks
+[drawbacks]: #drawbacks
+
+TBD
+
+# Rationale and Alternatives
+[alternatives]: #rationale-and-alternatives
+
+TBD
+
+# Unresolved Questions
+[unresolved]: #unresolved-questions
+
+1. Under what conditions do we remove the stake for Level 4 hotspots?
+2. Where does the removed stake go to? Does it just vanish?
+3. How do we actually remove the stake?
+
+# Deployment Impact
+[deployment-impact]: #deployment-impact
+
+We need to ensure we transition the existing hotspots on the network in a meaningful way. Whether every single existing
+hotspot goes into the same level or not is yet to be determined.
+
+# Success Metrics
+[success-metrics]: #success-metrics
+
+NA