CW1 Subkeys

This builds on cw1-whitelist to provide the first non-trivial solution. It still works like cw1-whitelist with a set of admins (typically 1) which have full control of the account. However, you can then grant a number of accounts allowances to send native tokens from this account.

This was proposed in Summer 2019 for the Cosmos Hub and resembles the functionality of ERC20 (allowances and transfer from).

Details

Basically, any admin can add an allowance for a (spender, denom) pair (similar to cw20 IncreaseAllowance / DecreaseAllowance). Any non-admin account can try to execute a CosmosMsg::Bank(BankMsg::Send{}) from this contract and if they have the required allowances, their allowance will be reduced and the send message relayed. If they don't have sufficient authorization, or if they try to proxy any other message type, then the attempt will be rejected. Admin can give permissions to subkeys to relay specific types of messages (covers Delegate, Undelegate, Redelegate, Withdraw for now). Subkeys have no permission on creation, it can be setup with SetupPermission message.

Messages

This adds 2 messages beyond the cw1 spec:

enum HandleMsg {
    IncreaseAllowance {
        spender: HumanAddr,
        denom: String,
        amount: Uint128,
        expires: Option<Expiration>,
    },
    DecreaseAllowance {
        spender: HumanAddr,
        denom: String,
        amount: Uint128,
        expires: Option<Expiration>,
    },
    SetupPermissions {
        spender: HumanAddr,
        permissions: Permissions,
    }
}

Queries

It also adds one more query type:

enum QueryMsg {
    Allowance {
        spender: HumanAddr,
    },
    AllAllowances {
        start_after: Option<HumanAddr>,
        limit: Option<u32>,
    },
}

pub struct AllowanceInfo {
    pub spender: HumanAddr,
    pub balance: Balance,
    pub expires: Expiration,
    pub permissions: Permissions,
}

pub struct AllAllowancesResponse {
    pub allowances: Vec<AllowanceInfo>,
}

Running this contract

You will need Rust 1.44.1+ with wasm32-unknown-unknown target installed.

You can run unit tests on this via:

cargo test

Once you are happy with the content, you can compile it to wasm via:

RUSTFLAGS='-C link-arg=-s' cargo wasm
cp ../../target/wasm32-unknown-unknown/release/cw1_subkeys.wasm .
ls -l cw1_subkeys.wasm
sha256sum cw1_subkeys.wasm

Or for a production-ready (compressed) build, run the following from the repository root:

docker run --rm -v "$(pwd)":/code \
  --mount type=volume,source="cosmwasm_plus_cache",target=/code/target \
  --mount type=volume,source=registry_cache,target=/usr/local/cargo/registry \
  cosmwasm/workspace-optimizer:0.10.2

The optimized contracts are generated in the artifacts/ directory.