path: root/accounts/accounts.go

// Copyright 2017 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

// Package accounts implements high level Ethereum account management.
package accounts

import (
    "math/big"

    ethereum "github.com/ethereum/go-ethereum"
    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/core/types"
    "github.com/ethereum/go-ethereum/event"
)

// Account represents an Ethereum account located at a specific location defined
// by the optional URL field.
type Account struct {
    Address common.Address `json:"address"` // Ethereum account address derived from the key
    URL     URL            `json:"url"`     // Optional resource locator within a backend
}

// Wallet represents a software or hardware wallet that might contain one or more
// accounts (derived from the same seed).
type Wallet interface {
    // URL retrieves the canonical path under which this wallet is reachable. It is
    // user by upper layers to define a sorting order over all wallets from multiple
    // backends.
    URL() URL

    // Status returns a textual status to aid the user in the current state of the
    // wallet.
    Status() string

    // Open initializes access to a wallet instance. It is not meant to unlock or
    // decrypt account keys, rather simply to establish a connection to hardware
    // wallets and/or to access derivation seeds.
    //
    // The passphrase parameter may or may not be used by the implementation of a
    // particular wallet instance. The reason there is no passwordless open method
    // is to strive towards a uniform wallet handling, oblivious to the different
    // backend providers.
    //
    // Please note, if you open a wallet, you must close it to release any allocated
    // resources (especially important when working with hardware wallets).
    Open(passphrase string) error

    // Close releases any resources held by an open wallet instance.
    Close() error

    // Accounts retrieves the list of signing accounts the wallet is currently aware
    // of. For hierarchical deterministic wallets, the list will not be exhaustive,
    // rather only contain the accounts explicitly pinned during account derivation.
    Accounts() []Account

    // Contains returns whether an account is part of this particular wallet or not.
    Contains(account Account) bool

    // Derive attempts to explicitly derive a hierarchical deterministic account at
    // the specified derivation path. If requested, the derived account will be added
    // to the wallet's tracked account list.
    Derive(path DerivationPath, pin bool) (Account, error)

    // SelfDerive sets a base account derivation path from which the wallet attempts
    // to discover non zero accounts and automatically add them to list of tracked
    // accounts.
    //
    // Note, self derivaton will increment the last component of the specified path
    // opposed to decending into a child path to allow discovering accounts starting
    // from non zero components.
    //
    // You can disable automatic account discovery by calling SelfDerive with a nil
    // chain state reader.
    SelfDerive(base DerivationPath, chain ethereum.ChainStateReader)

    // SignHash requests the wallet to sign the given hash.
    //
    // It looks up the account specified either solely via its address contained within,
    // or optionally with the aid of any location metadata from the embedded URL field.
    //
    // If the wallet requires additional authentication to sign the request (e.g.
    // a password to decrypt the account, or a PIN code o verify the transaction),
    // an AuthNeededError instance will be returned, containing infos for the user
    // about which fields or actions are needed. The user may retry by providing
    // the needed details via SignHashWithPassphrase, or by other means (e.g. unlock
    // the account in a keystore).
    SignHash(account Account, hash []byte) ([]byte, error)

    // SignTx requests the wallet to sign the given transaction.
    //
    // It looks up the account specified either solely via its address contained within,
    // or optionally with the aid of any location metadata from the embedded URL field.
    //
    // If the wallet requires additional authentication to sign the request (e.g.
    // a password to decrypt the account, or a PIN code o verify the transaction),
    // an AuthNeededError instance will be returned, containing infos for the user
    // about which fields or actions are needed. The user may retry by providing
    // the needed details via SignTxWithPassphrase, or by other means (e.g. unlock
    // the account in a keystore).
    SignTx(account Account, tx *types.Transaction, chainID *big.Int) (*types.Transaction, error)

    // SignHashWithPassphrase requests the wallet to sign the given hash with the
    // given passphrase as extra authentication information.
    //
    // It looks up the account specified either solely via its address contained within,
    // or optionally with the aid of any location metadata from the embedded URL field.
    SignHashWithPassphrase(account Account, passphrase string, hash []byte) ([]byte, error)

    // SignTxWithPassphrase requests the wallet to sign the given transaction, with the
    // given passphrase as extra authentication information.
    //
    // It looks up the account specified either solely via its address contained within,
    // or optionally with the aid of any location metadata from the embedded URL field.
    SignTxWithPassphrase(account Account, passphrase string, tx *types.Transaction, chainID *big.Int) (*types.Transaction, error)
}

// Backend is a "wallet provider" that may contain a batch of accounts they can
// sign transactions with and upon request, do so.
type Backend interface {
    // Wallets retrieves the list of wallets the backend is currently aware of.
    //
    // The returned wallets are not opened by default. For software HD wallets this
    // means that no base seeds are decrypted, and for hardware wallets that no actual
    // connection is established.
    //
    // The resulting wallet list will be sorted alphabetically based on its internal
    // URL assigned by the backend. Since wallets (especially hardware) may come and
    // go, the same wallet might appear at a different positions in the list during
    // subsequent retrievals.
    Wallets() []Wallet

    // Subscribe creates an async subscription to receive notifications when the
    // backend detects the arrival or departure of a wallet.
    Subscribe(sink chan<- WalletEvent) event.Subscription
}

// WalletEvent is an event fired by an account backend when a wallet arrival or
// departure is detected.
type WalletEvent struct {
    Wallet Wallet // Wallet instance arrived or departed
    Arrive bool   // Whether the wallet was added or removed
}