Safer

Safer is a tool that helps you sign & submit transactions to a Safe, without requiring any interaction with Safe's backend or frontend.

Safer is a set of Foundry scripts that can be used as fallback in case Safe App is down and the blockchain is the only thing that can be trusted.

Safer enables submitting complex transactions without the need of intermediaries.

Safer unlocks true DAO resilience.

Getting Started

• Install Foundry.
• Run make to initialize the repository.
• Create a .env file from the template .env.example file.
  • Set the environment variable SENDER to the address used to execute the transaction on the Safe. If you don't execute the tx, you don't need to set it.
  • Use the environment variable SAFE_NONCE to override a transaction's nonce. Remove it to use the default, latest Safe nonce. Leave it blank to use nonce 0.
  • Use the environment variable FOUNDRY_ETH_RPC_URL to customize the RPC endpoint used. This is useful to interact with a Safe deployed on another chain than Ethereum mainnet (the default one).

Build a Safe tx

• Run make tx and follow the steps to create a Safe transaction using create-safe-tx; OR
• Put the transaction's raw data in data/tx.json

Create a batch

To create a batch of multiple transactions that will be executed atomically:

1. Add the MULTI_SEND_ADDR environment variable to your .env file with the MultiSend contract address for your Safe version (e.g., MULTI_SEND_ADDR=0x38869bf66a61cF6bDB996A6aE40D5853Fd43B526 for Safe 1.3.0 on Sepolia)
2. Create a data/batch.json file with an array of transaction objects
3. Run make prepare-batch to encode the batch into a single Safe transaction

Each transaction in the batch should follow this format:

[
    {
        "operation": 0,
        "to": "0x0000000000000000000000000000000000000000",
        "value": "0",
        "data": "0x"
    },
    {
        "operation": 1,
        "to": "0x0000000000000000000000000000000000000000", 
        "value": "1000000000000000000",
        "data": "0x1234567890abcdef"
    }
]

Where:

• operation: 0 for a call, 1 for a delegatecall
• to: target contract address
• value: amount of ETH to send (as a string)
• data: transaction data (must start with 0x)

The batch will be encoded using Safe's MultiSend contract and saved to data/tx.json for signing and execution.

Sign a Safe tx

1. To sign the data with a Ledger, run: make sign:ledger
2. Share the content of data/signatures.txt with the signer who will execute the transaction on the Safe

Batch signatures and execute transaction

1. Make sure at least threshold signatures are available in data/signatures.txt, each one per line
2. To execute the transaction on the Safe with a Ledger, run: make exec:ledger

Advanced options

Hardware Wallet support

With make sign & make exec, one can also use any other wallet provider available with cast:

• make cmd:interactive to input the private key to the command prompt
• make cmd:ledger to use a Ledger
• make cmd:trezor to use a Trezor
• make cmd:keystore to use a keystore
• make cmd:"private-key 0x..." if you really want to save your private key to your shell's history...

You can also append any cast parameter:

• make sign:"ledger --mnemonic 1 --mnemonic-index 1" or make exec:"ledger --mnemonics foo --mnemonic-indexes 1" to use another account than the default one at index 0

Transaction details

{
  "to": "0x0000000000000000000000000000000000000000",
  "value": "0", // The tx value (in ETH), must be a string
  "data": "0x", // The raw tx data, must start with 0x
  "operation": 0, // 0 for a call, 1 for a delegatecall
  "safeTxGas": 0,
  "baseGas": 0,
  "gasPrice": 0,
  "gasToken": "0x0000000000000000000000000000000000000000", // Indicates the tx will consume the chain's default gas token (ETH on mainnet)
  "refundReceiver": "0x0000000000000000000000000000000000000000" // Indicates the tx's refund receiver will be the address executing the tx
}