ERC 734+735

This is an attempt at an implementation of ERC 734 and ERC 735, following the specs as closely as possible. It uses the Truffle framework and Ganache CLI for testing.

Overview

The smart contract implements the following features:

1. deploy contract using initial set of keys (Identity.sol)
2. add/remove keys to identity (KeyManager.sol)
3. get key data, in multiple ways (KeyGetters.sol)
4. "proxy contract" execution on the blockchain (MultiSig.sol)
5. multi-signature mechanism for MANAGEMENT_KEY and EXECUTION_KEY (MultiSig.sol)
6. add/remove claims to identity (ClaimManager.sol)
7. get claim data, in multiple ways (ClaimManager.sol)
8. refresh claims in identity (ClaimManager.sol)
9. ability to pause/unpause the contract, potentially with multi-sig (Pausable.sol)
10. ability to destroy the contract and return funds, potentially with multi-sig (Destructible.sol)

Architecture

The implementation tries to make extensive use of Solidity patterns for modular code i.e. libraries, abstract contracts and multiple inheritence. Here's how the class diagram looks:

                +--------------+         +------------+
                |              |         |            |
                |    ERC 165   |         | KeyStore** |
                |              |         |            |
                +---+--------+-+         +----+-------+
                    |        |                |
               +----v-----+ +v---------+ +----v-----+
               |          | |          | |          |
 +-------------+ ERC 735* | | ERC 734* | | KeyBase* |
 |             |          | |          | |          |
 |             +----------+ ++-+----+--+ +--+-------+------+--------------+
 |                           | |    |       |              |              |
 |                           | |    |       |              |              |
 |   +-----------------------+ |    | +-----+-----+  +-----v-----+ +------v-------+
 |   |                         |    | |           |  |           | |              |
 |   |                 +-------|----|-+  Pausable |  | KeyGetter | | Destructible |
 |   |    +--------------------|----|-+           |  |           | |              |
 |   |    |            |       |    | +--+--------+  +-+---------+ +--+-----------+
 |   |    |            |  +----+    |    |             |              |
 |   |    |            |  |         |    |             |              |
 |   |    |            |  |         |    |             |              |
 |   |    |            |  |         |    |             |              |
+v---v----v---+ +------v--v---+  +--v----v--+          |              |
|             | |             |  |          |          |              |
|ClaimManager | | KeyManager  |  | MultiSig |          |              |
|             | |             |  |          |          |              |
+---+---------+ ++------------+  +--+-------+          |              |
    |            |                  |                  |              |
    |            |                  |                  |              |
    |            |        +---------v------------------v---+          |
    |            |        |                                <----------+
    |            +-------->            Identity            |
    |                     |          (ERC 734+735)         |
    +--------------------->                                |
                          +--------------------------------+

* = Abstract contract
** = Library

Tests

Truffle tests exists for each contract, in separate files in the test/ folder. Each tests tries to count how much gas it's using for setup and during the test. Also, at the end I'm printing out total gas used for all tests.

$ ganache-cli --allowUnlimitedContractSize -l 10000000
...
$ truffle test
...
  ✓ should be paused/unpaused by management keys (86435 gas)
	  Test only: 59,944 gas

  54 passing (1m)

Currently missing unit tests for events being emitted.

Open issues

1. uri is not included in the signature and could theoretically be changed without changing a claim signature. Is this intentional or not?
2. Claim IDs are generated using keccak256(address issuer + uint256 _topic), which doesn't work great for self-claims i.e. issuer is address(this) and we might want multiple self-claims with the same topic
3. Added an ExecutionFailed event in ERC734 which isn't part of the standard
4. For execution requests, I'm using the multi-sig threshold at the time of request, not the one at the time of execution - is that a good idea? (e.g. you request an execution, threshold is X, wait for approvals, threshold is increased to Y, initial execution is approval with X approvals)
5. Using ERC 165 pseudo-introspection to check if an address implements ERC 734 or 735. Is this the best pattern for that?
6. Added a PROFILE_TOPIC claim topic which isn't part of the standard. The intended use is to store a plain-text profile URL in data (social media, blogs, etc.). As a convention, uri should be equal to data.
7. Added a LABEL_TOPIC claim topic which isn't part of the standard. The intended use is to store a plain-text label in data (real name, business name, nick name, brand name, alias, etc.).
8. The "proxy contract" only supports .call, doesn't support .delegateacall or creating a new contract on behalf of the identity.