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rewarding

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This commit is contained in:
Anatoly Yakovenko
2019-01-30 10:06:36 -08:00
committed by Greg Fitzgerald
parent e684fafb68
commit 3cbbceec78
1 changed files with 14 additions and 13 deletions
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book/src/fork-selection.md
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@ -8,17 +8,18 @@ voters need to recover from voting on such forks.
* Many forks may be votable by different voters, and each voter may see a * Many forks may be votable by different voters, and each voter may see a
different set of votable forks. The selected forks should eventually converge different set of votable forks. The selected forks should eventually converge
for the network. for the cluster.
* Reward based votes have an associated risk. Voters should have the ability to * Reward based votes have an associated risk. Voters should have the ability to
configure how much risk they take on. configure how much risk they take on.
* The [cost of rollback](#cost-of-rollback) is important to clients that rely on * The [cost of rollback](#cost-of-rollback) needs to be computable. It is
a measure of Consistency. It needs to be computable, and increase important to clients that rely on some measurable form of Consistency. The
super-linearly for older votes. costs to break consistency need to be computable, and increase super-linearly
for older votes.
* ASIC speeds are different between nodes, and attackers could employ Proof of * ASIC speeds are different between nodes, and attackers could employ Proof of
History ASICS that are much faster than the rest of the network. Consensus History ASICS that are much faster than the rest of the cluster. Consensus
needs to be resistant to attacks that exploit the variability in Proof of needs to be resistant to attacks that exploit the variability in Proof of
History ASIC speed. History ASIC speed.
@ -107,7 +108,7 @@ votes.
### Slashing and Rewards ### Slashing and Rewards
Voters should be rewarded for selecting the fork that the rest of the network Voters should be rewarded for selecting the fork that the rest of the cluster
selected as often as possible. This is well-aligned with generating a reward selected as often as possible. This is well-aligned with generating a reward
when the vote stack is full and the oldest vote needs to be dequeued. Thus a when the vote stack is full and the oldest vote needs to be dequeued. Thus a
reward should be generated for each successful dequeue. reward should be generated for each successful dequeue.
@ -125,10 +126,10 @@ confirmed *fork A*.
### Thresholds ### Thresholds
Each voter can independently set a threshold of network commitment to a fork Each voter can independently set a threshold of cluster commitment to a fork
before that voter commits to a fork. For example, at vote stack index 7, the before that voter commits to a fork. For example, at vote stack index 7, the
lockout is 256 time units. A voter may withhold votes and let votes 0-7 expire lockout is 256 time units. A voter may withhold votes and let votes 0-7 expire
unless the vote at index 7 has at greater than 50% commitment in the network. unless the vote at index 7 has at greater than 50% commitment in the cluster.
This allows each voter to independently control how much risk to commit to a This allows each voter to independently control how much risk to commit to a
fork. Committing to forks at a higher frequency would allow the voter to earn fork. Committing to forks at a higher frequency would allow the voter to earn
more rewards. more rewards.
@ -140,9 +141,9 @@ These parameters need to be tuned.
* Number of votes in the stack before dequeue occurs (32). * Number of votes in the stack before dequeue occurs (32).
* Rate of growth for lockouts in the stack (2x). * Rate of growth for lockouts in the stack (2x).
* Starting default lockout (2). * Starting default lockout (2).
* Threshold depth for minimum network commitment before committing to the fork * Threshold depth for minimum cluster commitment before committing to the fork
(8). (8).
* Minimum network commitment size at threshold depth (50%+). * Minimum cluster commitment size at threshold depth (50%+).
### Free Choice ### Free Choice
@ -158,7 +159,7 @@ service. Two options exits for voter:
* a voter can withhold a vote to observe multiple forks before voting * a voter can withhold a vote to observe multiple forks before voting
In both cases, the voters in the network have several forks to pick from In both cases, the voters in the cluster have several forks to pick from
concurrently, even though each fork represents a different height. In both concurrently, even though each fork represents a different height. In both
cases it is impossible for the protocol to detect if the voter behavior is cases it is impossible for the protocol to detect if the voter behavior is
intentional or not. intentional or not.
@ -196,14 +197,14 @@ must satisfy the *Greedy Choice* rule.
3. Fork must have a greater amount of cluster transaction fees. 3. Fork must have a greater amount of cluster transaction fees.
This attack is then limited to censoring the previous leaders fees, and This attack is then limited to censoring the previous leaders fees, and
individual transactions. But it cannot halt the network, or reduce the individual transactions. But it cannot halt the cluster, or reduce the
validator set compared to the concurrent fork. Fee censorship is limited to validator set compared to the concurrent fork. Fee censorship is limited to
access fees going to the leaders but not the validators. access fees going to the leaders but not the validators.
### ASIC Rollback ### ASIC Rollback
An attacker generates a concurrent fork from an older block to try to rollback An attacker generates a concurrent fork from an older block to try to rollback
the network. In this attack the concurrent fork is competing with forks that the cluster. In this attack the concurrent fork is competing with forks that
have already been voted on. This attack is limited by the exponential growth of have already been voted on. This attack is limited by the exponential growth of
the lockouts. the lockouts.