NuCypherTokenERC20 token contract
StakingEscrowHolds Ursula’s stake, stores information about Ursula’s activity, and assigns a reward for participating in the NuCypher network. (The
Issuercontract is part of the
PolicyManagerHolds a policy’s fee and distributes fee by periods
AdjudicatorManages the slashing protocol
WorkLockManages token distribution
UpgradeableBase contract for upgrading
DispatcherProxy to other contracts and provides upgrading of the
StakingInterfaceInterface for accessing main contracts from a staking contract
StakingInterfaceRouterRouter for accessing
AbstractStakingContractBase contract for implementing staker-contract concept
This section provides a step-by-step guide of how NuCypher contracts are deployed.
NuCypherTokenwith all future supply tokens
Deploy stub for
StakingEscrowwith a dispatcher targeting it
PolicyManagerwith its own dispatcher, also targeting it
Adjudicatorwith a dispatcher
StakingEscrowand retarget its dispatcher by using the
Approve tokens transfer to the
StakingEscrowcontract. These tokens are future staking rewards
initialize(uint256)method to initialize the
Approve tokens transfer for distribution to the
WorkLockcontract and call
Alice’s Contract Interaction¶
Alice Revokes a Blockchain Policy¶
When Alice wants to revoke a policy, she calls the
Execution of these methods results in Alice recovering all fees for future periods, and also for periods when the stakers were inactive.
Alice can refund ETH for any inactive periods without revoking the policy by using the method
If Alice can’t execute an on-chain transaction or wants to share the ability to revoke, then she can sign revocation parameters. Anyone who has this signature will be able to revoke policy using
PolicyManager.revoke(bytes16, address, bytes)
Staker’s Contract Interaction¶
Staker Locks Tokens¶
In order to become a participant of the network, a staker stakes tokens in the
The staker allows the (staking) contract to perform a transaction using the
NuCypherToken.approve(address, uint256) method
(ERC20 contracts allow access delegation to another address).
After that, the staker transfers some quantity of tokens (
StakingEscrow.deposit(uint256, uint16)), locking them at the same time.
NucypherToken.approveAndCall(address, uint256, bytes) method can be used.
The parameters are:
The address of the
Dispatcherthat targets the
The amount of staked tokens
When staking tokens, the staker sets the number of periods the tokens will be locked, which must be no less than some minimal locking time (30 periods).
In order to unlock tokens, the staker must be active during the time of locking (and make a commitment each period).
Each stake is represented by the amount of tokens locked, and the stake’s duration in periods.
The staker can add a new stake using
StakingEscrow.deposit(uint256, uint16) or
StakingEscrow.lock(uint256, uint16) methods.
The staker can split stake into two parts: one with the same duration and another with an extended duration.
For this purpose, the
StakingEscrow.divideStake(uint256, uint256, uint16) method is used.
The first parameter is used to identify the stake to divide and the last two for the extended part of the stake.
When calculating locked tokens using the
StakingEscrow.getLockedTokens(address, uint16) method, all stakes that are active during the specified period are summed.
The Staker Bonds to a Worker (“Ursula”)¶
The staker must specify a worker who will make a commitment and sign on behalf of this staker by calling the
Bonding a new worker is allowed no more than once within
Only the worker can make a commitment.
Ursula Makes a Commitment¶
In order to make a commitment to the next period, workers call
StakingEscrow.commitToNextPeriod() wherein activities for the next period are registered.
The staker gets a reward for every commitment period.
Ursula Generates Staking Rewards¶
After the period of activity has passed, the staker may call
StakingEscrow.mint() method which computes and transfers tokens to the staker’s account.
Also note that calls to
StakingEscrow.commitToNextPeriod() are included the
The reward value depends on the fraction of locked tokens for the period (only those who made a commitment are accounted for).
Also, the reward depends on the number of periods during which the tokens will be locked: if the tokens will be locked for half a year, the coefficient is 1.5.
The minimum coefficient is 1 (when tokens will get unlocked in the next period), and the maximum is 2 (when the time is 1 year or more).
The reward is calculated separately for each stake that is active during the mining period and all rewards are summed up.
The order of calling
StakingEscrow.mint() by stakers (e.g. who calls first, second etc) doesn’t matter.
Stakers can claim their rewards by using the
StakingEscrow.withdraw(uint256) method. Only non-locked tokens can be withdrawn.
Ursula Generates Policy Fees¶
Also the staker gets fees for policies deployed.
Computation of a policy fee happens every time
StakingEscrow.mint() is called by the
PolicyManager.updateFee(address, uint16) method.
In order to take the fee, the staker needs to call method
withdraw() of the contract
The staker can set a minimum fee rate for a policy. For that, the staker should call the
Upgradeable contracts, such as
StakingInterface, have their version specified in contract doc inside @dev.
Version format is
i - major version,
j - minor version,
k - patch, for example
Different major versions mean different forks and they are not upgradeable
Minor versions relate to any signatures or state changes inside contract, contracts are upgradeable between minor versions, but have different ABI and follows different agent layers
Patches involve changes inside function(s) with signature(s) untouched. All patches with a common minor version can be upgraded from one to another without other changes