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Deposit Security Committee manual

This instruction has been prepared for the participants of the Deposit Security Committee and describes the general points, the preparation steps to act as a guardian, and the details of the protection mechanism. The Deposit Security Committee is necessary to prevent the substitution of withdrawal credentials with frontrunning by node operators. Each member of the committee must perform several actions to ensure the security of deposits made by Lido. To participate in the validation, you will need to deploy a lido-council-daemon and prepare a private key for signing messages about the correctness of data or the need to stop deposits in case of attack.


Before running in the mainnet all steps should be done in the Goerli testnet.

  1. Prepare an EOA account for signing data with a private key on hand (not in hardware wallet). It will be a moderately sensitive hot private key. Use different accounts for testnet and mainnet.
  2. Send the account address to Lido for submitting it to the smart contract.
  3. Deploy and run lido-council-daemon with the private key from the EOA account. It would work in a dry-run mode until your address would be included in the smart contract.

Detailed description

The vulnerability

There is the vulnerability allowing the malicious Node Operator to intercept the user funds on deposits to the Beacon chain in the Lido protocol. The vulnerability could only be exploited by the Node Operator front-running the Lido.depositBufferedEther transaction with direct deposit to the DepositContract of no less than 1 ETH with the same validator public key & withdrawal credentials different from the Lido’s ones, effectively getting control over 32 ETH from Lido. To mitigate this, Lido contracts should be able to check that Node Operators’ keys hadn’t been used for malicious pre-deposits.

The Deposit Security Committee

We propose to establish the Deposit Security Committee dedicated to ensuring the safety of deposits on the Beacon chain:

  • monitoring the history of deposits and the set of Lido keys available for the deposit, signing and disseminating messages allowing deposits;
  • signing the special message allowing anyone to pause deposits once the malicious Node Operator pre-deposits are detected.

To make a deposit, we propose to collect a quorum of 2/3 of the signatures of the committee members. Members of the committee can collude with node operators and steal money by signing bad data that contains malicious pre-deposits. To mitigate this we propose to allow single committee member to stop deposits and also enforce space deposits in time (e.g. no more than 150 deposits with 150 blocks in between them), to provide single honest participant an ability to stop further deposits even if the supermajority colludes. The idea was outlined on research forum post as the option d.

Committee membership

The first set of guardians is six node operators (Stakefish, Skillz, Chorus one, Blockscape, Staking facilities, P2P) and Lido dev team. In the future, we want to bring as many node operators as possible into the mix, so the expectation will be that while the 7 guardians start the rest of the node operators can also participate via testnet and gradually get pulled into mainnet.

Members responsibilities

Each member must prepare an EOA account to sign the pair (depositRoot, keysOpIndex) with its private key. The addresses of the committee members will be added to the smart contract. Also, member has to run DSC Daemonthat monitors the validators’ public keys in the DepositContract and NodeOperatorRegistry. The daemon must have access to the committee member’s private key to be able to perform ECDSA signing.

The daemon constantly watches all updates in DepositContract and NodeOperatorRegistry:

  • If the state is correct, it signes the current to_sign struct and emits it to an off-chain message queue.
  • If the state has malicious pre-deposits, it signs the “something’s wrong” message at the current block, emits it to a message queue, and attempts to send pauseDeposits() tx.

Preparation steps

Before running in the mainnet, all steps should be completed in the Goerli testnet.

EOA account

It might be any EOA account under the member's control. Send the address of its account to Lido for submitting it to the smart contract. Lido will provide some ETH to make stopping transactions if needed (shouldn't ever be the case). Note, all actions, except sending the stop message, would be done off-chain.

Run lido-council-daemon

For perform deposits validation each member should run the lido-council-daemon from repository.

The daemon monitors the keys in the deposit contract and compares them with Lido's unused keys. The result of the comparison is signed with the private key and sent to the message broker. If the daemon finds a match, it tries to stop the deposits by sending a transaction calling the pauseDeposits method on the Deposit Security Module contract.

Run with docker

You can pull image from the the docker hub and run it manually or via docker-compose (docker-compose.yml can be found in repository root). Volumes can be omitted if needed.

docker pull lidofinance/lido-council-daemon@sha256:9943ed50556fc8bf75c1179023c33dc30ef9efc6ee4f4f29bfed2fc5bc23ad64

docker run -i -t \
-v ${PWD}/.volumes/council/cache:/council/cache/ \
-p 3000:3000/tcp \
-e PORT='3000' \
-e LOG_LEVEL='debug' \
-e LOG_FORMAT='simple' \
-e RPC_URL='<rpc url>' \
-e KAFKA_SSL='true' \
-e KAFKA_USERNAME='<kafka user>' \
-e KAFKA_PASSWORD='<kafka password>' \
-e KAFKA_BROKER_ADDRESS_1='<kafka address>' \
-e KAFKA_TOPIC=defender \

Port 3000 is used for prometheus metrics. You don't have to expose it if you don't collect metrics.

RPC_URL is the URI to web3 RPC you want to use (Goerli for testnet). WALLET_PRIVATE_KEY environment variable should be managed as a sensitive secret. The key should be in the 0xabcd... format.

Note: every time the container starts fresh it warms up cache of historical data, stored in the volume you provide. Cache warming takes a lot of RPC queries and up to 30m of time. That cache is fully deterministic, fairly easily repopulated and you shouldn't be afraid to lose it.

Run from source code

  1. Clone the repository:
git clone
cd lido-council-daemon
  1. Install dependencies:
yarn install
yarn typechain
  1. Copy the contents of sample.env to .env file
cp sample.env .env
  1. Configure daemon through environment variables in the previously created .env file:

Messages broker, i.e. Kafka:

KAFKA_USERNAME=<kafka username>
KAFKA_PASSWORD=<kafka password>
KAFKA_BROKER_ADDRESS_1=<kafka broker address with port>

A message broker is needed for data exchange between consuls and a depositor bot.

The URI to web3 RPC you want to use (Goerli for testnet):

RPC_URL=<rpc url>
  1. Set private through environment variable (in the 0xabcd... format):
export WALLET_PRIVATE_KEY=<your-private-key>

It is better not to store your private key in the .env file.

  1. Run:
yarn build
yarn start:prod

Note: every time the the daemons starts for the first time it warms up local cache of historical data, which takes a lot of RPC queries and about 30m of time. That cache is fully deterministic, fairly easily repopulated and you shouldn't be afraid to lose it.

Possible startup messages

All goes well:

info: Account balance is sufficient {"balance":"1.0 ETH"}
info: You address is in the Guardian List {"address":"0x0000000000000000000000000000000000000000"}
debug: Fresh events are fetched {"startBlock":5679826,"endBlock":5679976,"events":6}
debug: Fresh events are fetched {"startBlock":5679827,"endBlock":5679977,"events":6}
debug: Fresh events are fetched {"startBlock":5679828,"endBlock":5679978,"events":7}
info: No problems found {"type":"deposit","depositRoot":"0xc2c9308fa425a64ef9cac1837412ba462b6429fce2f170184284a260b735638c","keysOpIndex":12,"blockNumber":5679978,"blockHash":"0x87762c941f653f2f70157f86deac78f19e4d1549e231a52d1191289592d1a0ab","guardianAddress":"0x3dc4cF780F2599B528F37dedB34449Fb65Ef7d4A","guardianIndex":0,"signature":{"r":"0x44fec2e6fd34e74b8f001ef0e5bbd2db6d3179925fb82cb43231e19af46f0ddd","s":"0x2ff4326af760e353803458b75279eb8f58e5735b3565ea16bcd0f773bce106a4","_vs":"0xaff4326af760e353803458b75279eb8f58e5735b3565ea16bcd0f773bce106a4","recoveryParam":1,"v":28}}
debug: Fresh events are fetched {"startBlock":5679829,"endBlock":5679979,"events":7}

At the first startup the daemon will collect historical data for quite some time:

info: Historical events are fetched {"endBlock":4487322,"events":3,"startBlock":4467323}

Private key is not provided:

warn: Private key is not provided, a random address will be generated for the test run

Not enough ether on a user balance:

warn: Account balance is too low {"balance":"0.0 ETH"}

Dry-run case, your address is not in the smart contract:

warn: You address is not in the Guardian List {"address":"0x0000000000000000000000000000000000000000"}