Add ERC-7579 modules docs and EIP-7702 note in accounts docs (#157)

Co-authored-by: Arr00 <[email protected]>
Co-authored-by: Gonzalo Othacehe <[email protected]>

Author: 3 people

contracts/mocks/account/modules/ERC7579MultisigMocks.sol

@@ -26,7 +26,7 @@ abstract contract ERC7579MultisigExecutorMock is EIP712, ERC7579Executor, ERC757
         bytes32 mode,
         bytes calldata data
     ) internal view override returns (bytes calldata) {
-        uint16 executionCalldataLength = uint16(uint256(bytes32(data[0:2]))); // First 2 bytes are the length
+        uint16 executionCalldataLength = uint16(bytes2(data[0:2])); // First 2 bytes are the length
         bytes calldata executionCalldata = data[2:2 + executionCalldataLength]; // Next bytes are the calldata
         bytes32 typeHash = _getExecuteTypeHash(account, salt, mode, executionCalldata);
         require(_rawERC7579Validation(account, typeHash, data[2 + executionCalldataLength:])); // Remaining bytes are the signature
@@ -39,7 +39,7 @@ abstract contract ERC7579MultisigExecutorMock is EIP712, ERC7579Executor, ERC757
         bytes32 mode,
         bytes calldata executionCalldata
     ) internal view returns (bytes32) {
-        return _hashTypedDataV4(keccak256(abi.encode(EXECUTE_OPERATION, account, mode, executionCalldata, salt)));
+        return _hashTypedDataV4(keccak256(abi.encode(EXECUTE_OPERATION, account, salt, mode, executionCalldata)));
     }
 }
 
@@ -58,7 +58,7 @@ abstract contract ERC7579MultisigWeightedExecutorMock is EIP712, ERC7579Executor
         bytes32 mode,
         bytes calldata data
     ) internal view override returns (bytes calldata) {
-        uint16 executionCalldataLength = uint16(uint256(bytes32(data[0:2]))); // First 2 bytes are the length
+        uint16 executionCalldataLength = uint16(bytes2(data[0:2])); // First 2 bytes are the length
         bytes calldata executionCalldata = data[2:2 + executionCalldataLength]; // Next bytes are the calldata
         bytes32 typeHash = _getExecuteTypeHash(account, salt, mode, executionCalldata);
         require(_rawERC7579Validation(account, typeHash, data[2 + executionCalldataLength:])); // Remaining bytes are the signature
@@ -71,7 +71,7 @@ abstract contract ERC7579MultisigWeightedExecutorMock is EIP712, ERC7579Executor
         bytes32 mode,
         bytes calldata executionCalldata
     ) internal view returns (bytes32) {
-        return _hashTypedDataV4(keccak256(abi.encode(EXECUTE_OPERATION, account, mode, executionCalldata, salt)));
+        return _hashTypedDataV4(keccak256(abi.encode(EXECUTE_OPERATION, account, salt, mode, executionCalldata)));
     }
 }
 
@@ -90,7 +90,7 @@ abstract contract ERC7579MultisigConfirmationExecutorMock is ERC7579Executor, ER
         bytes32 mode,
         bytes calldata data
     ) internal view override returns (bytes calldata) {
-        uint16 executionCalldataLength = uint16(uint256(bytes32(data[0:2]))); // First 2 bytes are the length
+        uint16 executionCalldataLength = uint16(bytes2(data[0:2])); // First 2 bytes are the length
         bytes calldata executionCalldata = data[2:2 + executionCalldataLength]; // Next bytes are the calldata
         bytes32 typeHash = _getExecuteTypeHash(account, salt, mode, executionCalldata);
         require(_rawERC7579Validation(account, typeHash, data[2 + executionCalldataLength:])); // Remaining bytes are the signature
@@ -103,6 +103,6 @@ abstract contract ERC7579MultisigConfirmationExecutorMock is ERC7579Executor, ER
         bytes32 mode,
         bytes calldata executionCalldata
     ) internal view returns (bytes32) {
-        return _hashTypedDataV4(keccak256(abi.encode(EXECUTE_OPERATION, account, mode, executionCalldata, salt)));
+        return _hashTypedDataV4(keccak256(abi.encode(EXECUTE_OPERATION, account, salt, mode, executionCalldata)));
     }
 }

contracts/mocks/docs/account/MyAccountERC7579.sol

@@ -0,0 +1,15 @@
+// contracts/MyAccountERC7579.sol
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.27;
+
+import {IERC1271} from "@openzeppelin/contracts/interfaces/IERC1271.sol";
+import {Initializable} from "@openzeppelin/contracts/proxy/utils/Initializable.sol";
+import {MODULE_TYPE_VALIDATOR} from "@openzeppelin/contracts/interfaces/draft-IERC7579.sol";
+import {AccountERC7579} from "../../../account/extensions/AccountERC7579.sol";
+
+contract MyAccountERC7579 is Initializable, AccountERC7579 {
+    function initializeAccount(address validator, bytes calldata validatorData) public initializer {
+        // Install a validator module to handle signature verification
+        _installModule(MODULE_TYPE_VALIDATOR, validator, validatorData);
+    }
+}

contracts/mocks/docs/account/modules/MyERC7579DelayedSocialRecovery.sol

@@ -0,0 +1,57 @@
+// contracts/MyERC7579DelayedSocialRecovery.sol
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.27;
+
+import {EIP712} from "@openzeppelin/contracts/utils/cryptography/EIP712.sol";
+import {ERC7579Executor} from "../../../../account/modules/ERC7579Executor.sol";
+import {ERC7579Validator} from "../../../../account/modules/ERC7579Validator.sol";
+import {Calldata} from "@openzeppelin/contracts/utils/Calldata.sol";
+import {ERC7579DelayedExecutor} from "../../../../account/modules/ERC7579DelayedExecutor.sol";
+import {ERC7579Multisig} from "../../../../account/modules/ERC7579Multisig.sol";
+
+abstract contract MyERC7579DelayedSocialRecovery is EIP712, ERC7579DelayedExecutor, ERC7579Multisig {
+    bytes32 private constant RECOVER_TYPEHASH =
+        keccak256("Recover(address account,bytes32 salt,bytes32 mode,bytes executionCalldata)");
+
+    function isModuleType(uint256 moduleTypeId) public pure override(ERC7579Executor, ERC7579Validator) returns (bool) {
+        return ERC7579Executor.isModuleType(moduleTypeId) || ERC7579Executor.isModuleType(moduleTypeId);
+    }
+
+    // Data encoding: [uint16(executorArgsLength), executorArgs, uint16(multisigArgsLength), multisigArgs]
+    function onInstall(bytes calldata data) public override(ERC7579DelayedExecutor, ERC7579Multisig) {
+        uint16 executorArgsLength = uint16(bytes2(data[0:2])); // First 2 bytes are the length
+        bytes calldata executorArgs = data[2:2 + executorArgsLength]; // Next bytes are the args
+        uint16 multisigArgsLength = uint16(bytes2(data[2 + executorArgsLength:4 + executorArgsLength])); // Next 2 bytes are the length
+        bytes calldata multisigArgs = data[4 + executorArgsLength:4 + executorArgsLength + multisigArgsLength]; // Next bytes are the args
+
+        ERC7579DelayedExecutor.onInstall(executorArgs);
+        ERC7579Multisig.onInstall(multisigArgs);
+    }
+
+    function onUninstall(bytes calldata) public override(ERC7579DelayedExecutor, ERC7579Multisig) {
+        ERC7579DelayedExecutor.onUninstall(Calldata.emptyBytes());
+        ERC7579Multisig.onUninstall(Calldata.emptyBytes());
+    }
+
+    // Data encoding: [uint16(executionCalldataLength), executionCalldata, signature]
+    function _validateSchedule(
+        address account,
+        bytes32 salt,
+        bytes32 mode,
+        bytes calldata data
+    ) internal view override {
+        uint16 executionCalldataLength = uint16(bytes2(data[0:2])); // First 2 bytes are the length
+        bytes calldata executionCalldata = data[2:2 + executionCalldataLength]; // Next bytes are the calldata
+        bytes calldata signature = data[2 + executionCalldataLength:]; // Remaining bytes are the signature
+        require(_rawERC7579Validation(account, _getExecuteTypeHash(account, salt, mode, executionCalldata), signature));
+    }
+
+    function _getExecuteTypeHash(
+        address account,
+        bytes32 salt,
+        bytes32 mode,
+        bytes calldata executionCalldata
+    ) internal view returns (bytes32) {
+        return _hashTypedDataV4(keccak256(abi.encode(RECOVER_TYPEHASH, account, salt, mode, executionCalldata)));
+    }
+}

contracts/mocks/docs/account/modules/MyERC7579Modules.sol

@@ -0,0 +1,20 @@
+// contracts/MyERC7579Modules.sol
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.27;
+
+import {EIP712} from "@openzeppelin/contracts/utils/cryptography/EIP712.sol";
+import {IERC7579Module, IERC7579Hook} from "@openzeppelin/contracts/interfaces/draft-IERC7579.sol";
+import {ERC7579Executor} from "../../../../account/modules/ERC7579Executor.sol";
+import {ERC7579Validator} from "../../../../account/modules/ERC7579Validator.sol";
+
+// Basic validator module
+abstract contract MyERC7579RecoveryValidator is ERC7579Validator {}
+
+// Basic executor module
+abstract contract MyERC7579RecoveryExecutor is ERC7579Executor {}
+
+// Basic fallback handler
+abstract contract MyERC7579RecoveryFallback is IERC7579Module {}
+
+// Basic hook
+abstract contract MyERC7579RecoveryHook is IERC7579Hook {}

contracts/mocks/docs/account/modules/MyERC7579SocialRecovery.sol

@@ -0,0 +1,44 @@
+// contracts/MyERC7579SocialRecovery.sol
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.27;
+
+import {Nonces} from "@openzeppelin/contracts/utils/Nonces.sol";
+import {EIP712} from "@openzeppelin/contracts/utils/cryptography/EIP712.sol";
+import {ERC7579Executor} from "../../../../account/modules/ERC7579Executor.sol";
+import {ERC7579Validator} from "../../../../account/modules/ERC7579Validator.sol";
+import {ERC7579Multisig} from "../../../../account/modules/ERC7579Multisig.sol";
+
+abstract contract MyERC7579SocialRecovery is EIP712, ERC7579Executor, ERC7579Multisig, Nonces {
+    bytes32 private constant RECOVER_TYPEHASH =
+        keccak256("Recover(address account,bytes32 salt,uint256 nonce,bytes32 mode,bytes executionCalldata)");
+
+    function isModuleType(uint256 moduleTypeId) public pure override(ERC7579Executor, ERC7579Validator) returns (bool) {
+        return ERC7579Executor.isModuleType(moduleTypeId) || ERC7579Executor.isModuleType(moduleTypeId);
+    }
+
+    // Data encoding: [uint16(executionCalldataLength), executionCalldata, signature]
+    function _validateExecution(
+        address account,
+        bytes32 salt,
+        bytes32 mode,
+        bytes calldata data
+    ) internal override returns (bytes calldata) {
+        uint16 executionCalldataLength = uint16(bytes2(data[0:2])); // First 2 bytes are the length
+        bytes calldata executionCalldata = data[2:2 + executionCalldataLength]; // Next bytes are the calldata
+        bytes calldata signature = data[2 + executionCalldataLength:]; // Remaining bytes are the signature
+        require(_rawERC7579Validation(account, _getExecuteTypeHash(account, salt, mode, executionCalldata), signature));
+        return executionCalldata;
+    }
+
+    function _getExecuteTypeHash(
+        address account,
+        bytes32 salt,
+        bytes32 mode,
+        bytes calldata executionCalldata
+    ) internal returns (bytes32) {
+        return
+            _hashTypedDataV4(
+                keccak256(abi.encode(RECOVER_TYPEHASH, account, salt, _useNonce(account), mode, executionCalldata))
+            );
+    }
+}

docs/modules/ROOT/nav.adoc

@@ -3,6 +3,7 @@
 ** xref:accounts.adoc[Accounts]
 *** xref:eoa-delegation.adoc[EOA Delegation]
 *** xref:multisig.adoc[Multisig]
+*** xref:account-modules.adoc[Modules]
 ** xref:paymasters.adoc[Paymasters]
 * xref:crosschain.adoc[Crosschain]
 * xref:utilities.adoc[Utilities]

docs/modules/ROOT/pages/account-modules.adoc

@@ -0,0 +1,128 @@
+= Account Modules
+
+Smart accounts built with https://eips.ethereum.org/EIPS/eip-7579[ERC-7579] provide a standardized way to extend account functionality through modules (i.e. smart contract instances). This architecture allows accounts to support various features that are compatible with a wide variety of account implementations. See https://erc7579.com/modules[compatible modules].
+
+== ERC-7579
+
+ERC-7579 defines a standardized interface for modular smart accounts. This standard enables accounts to install, uninstall, and interact with modules that extend their capabilities in a composable manner with different account implementations.
+
+=== Accounts
+
+OpenZeppelin offers an implementation of an xref:api:account.adoc#AccountERC7579[`AccountERC7579`] contract that allows installing modules compliant with this standard. There's also an xref:api:account.adoc#AccountERC7579Hooked[`AccountERC7579Hooked`] variant that supports installation of hooks. Like xref:accounts.adoc#handling_initialization[most accounts], an instance should define an initializer function where the first module that controls the account will be set:
+
+[source,solidity]
+----
+include::api:example$account/MyAccountERC7579.sol[]
+----
+
+NOTE: For simplicity, the xref:api:account.adoc#AccountERC7579Hooked[`AccountERC7579Hooked`] only supports a single hook. A common workaround is to install a https://github.com/rhinestonewtf/core-modules/blob/7afffccb44d73dbaca2481e7b92bce0621ea6449/src/HookMultiPlexer/HookMultiPlexer.sol[single hook with a multiplexer pattern] to extend the functionality to multiple hooks.
+
+=== Modules
+
+Functionality is added to accounts through encapsulated functionality deployed as smart contracts called _modules_. The standard defines four primary module types:
+
+* *Validator modules (type 1)*: Handle signature verification and user operation validation
+* *Executor modules (type 2)*: Execute operations on behalf of the account
+* *Fallback modules (type 3)*: Handle fallback calls for specific function selectors
+* *Hook modules (type 4)*: Execute logic before and after operations
+
+Modules can implement multiple types simultaneously, which means you could combine an executor module with hooks to enforce behaviors on an account, such as maintaining ERC-20 approvals or preventing the removal of certain permissions.
+
+See https://erc7579.com/modules[popular module implementations].
+
+==== Building Custom Modules
+
+The library provides _standard composable modules_ as building blocks with an internal API for developers. By combining these components, you can create a rich set of variants without including unnecessary features.
+
+A good starting point is the xref:api:account.adoc#ERC7579Executor[`ERC7579Executor`] or xref:api:account.adoc#ERC7579Validator[`ERC7579Validator`], which include an opinionated base layer easily combined with other abstract modules. Hooks and fallback handlers are more straightforward to implement directly from interfaces:
+
+[source,solidity]
+----
+include::api:example$account/modules/MyERC7579Modules.sol[]
+----
+
+TIP: Explore these abstract ERC-7579 modules in the xref:api:account.adoc#modules[API Reference].
+
+==== Execution Modes
+
+ERC-7579 supports various execution modes, which are encoded as a `bytes32` value. The https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/account/utils/draft-ERC7579Utils.sol[`ERC7579Utils`] library provides utility functions to work with these modes:
+
+[source,solidity]
+----
+// Parts of an execution mode
+type Mode is bytes32;
+type CallType is bytes1;
+type ExecType is bytes1;
+type ModeSelector is bytes4;
+type ModePayload is bytes22;
+----
+
+===== Call Types
+
+Call types determine the kind of execution:
+
+[%header,cols="1,1,3"]
+|===
+|Type |Value |Description
+|`CALLTYPE_SINGLE` |`0x00` |A single `call` execution
+|`CALLTYPE_BATCH` |`0x01` |A batch of `call` executions
+|`CALLTYPE_DELEGATECALL` |`0xFF` |A `delegatecall` execution
+|===
+
+===== Execution Types
+
+Execution types determine how failures are handled:
+
+[%header,cols="1,1,3"]
+|===
+|Type |Value |Description
+|`EXECTYPE_DEFAULT` |`0x00` |Reverts on failure
+|`EXECTYPE_TRY` |`0x01` |Does not revert on failure, emits an event instead
+|===
+
+==== Execution Data Format
+
+The execution data format varies depending on the call type:
+
+* For single calls: `abi.encodePacked(target, value, callData)`
+* For batched calls: `abi.encode(Execution[])` where `Execution` is a struct containing `target`, `value`, and `callData`
+* For delegate calls: `abi.encodePacked(target, callData)`
+
+== Examples
+
+=== Social Recovery
+
+Social recovery allows an account to be recovered when access is lost by relying on trusted parties ("guardians") who verify the user's identity and help restore access.
+
+Social recovery is not a single solution but a design space with multiple configuration options:
+
+* Delay configuration
+* Expiration settings
+* Different guardian types
+* Cancellation windows
+* Confirmation requirements
+
+To support _different guardian types_, we can leverage ERC-7913 as discussed in the xref:multisig.adoc#beyond_standard_signature_verification[multisig] section. For ERC-7579 modules, this is implemented through the xref:api:account.adoc#ERC7579Multisig[`ERC7579Multisig`] validator.
+
+Combined with an xref:api:account.adoc#ERC7579Executor[`ERC7579Executor`], it provides a basic foundation that can be extended with more sophisticated features:
+
+[source,solidity]
+----
+include::api:example$account/modules/MyERC7579SocialRecovery.sol[]
+----
+
+For enhanced security, you can extend this foundation with scheduling, delays, and cancellations using xref:api:account.adoc#ERC7579DelayedExecutor[`ERC7579DelayedExecutor`]. This allows guardians to schedule recovery operations with a time delay, providing a security window to detect and cancel suspicious recovery attempts before they execute:
+
+[source,solidity]
+----
+include::api:example$account/modules/MyERC7579DelayedSocialRecovery.sol[]
+----
+
+NOTE: The delayed executor's signature validation doesn't require a nonce since operations are uniquely identified by their xref:api:account.adoc#ERC7579DelayedExecutor-hashOperation-address-bytes32-bytes32-bytes-[operation id] and cannot be scheduled twice.
+
+These implementations demonstrate how to build progressively more secure social recovery mechanisms, from basic multi-signature recovery to time-delayed recovery with cancellation capabilities.
+
+For additional functionality, developers can use:
+
+* xref:api:account.adoc#ERC7579MultisigWeighted[`ERC7579MultisigWeighted`] to assign different weights to signers
+* xref:api:account.adoc#ERC7579MultisigConfirmation[`ERC7579MultisigConfirmation`] to implement a confirmation system that verifies signatures when adding signers

docs/modules/ROOT/pages/accounts.adoc

@@ -290,3 +290,19 @@ A common security practice to prevent user operation https://mirror.xyz/curiousa
 The problem with this approach is that the user might be prompted by the wallet provider to sign an https://x.com/howydev/status/1780353754333634738[obfuscated message], which is a phishing vector that may lead to a user losing its assets.
 
 To prevent this, developers may use xref:api:account#ERC7739Signer[`ERC7739Signer`], a utility that implements https://docs.openzeppelin.com/contracts/5.x/api/interfaces#IERC1271[`IERC1271`] for smart contract signatures with a defensive rehashing mechanism based on a https://github.com/frangio/eip712-wrapper-for-eip1271[nested EIP-712 approach] to wrap the signature request in a context where there's clearer information for the end user.
+
+=== EIP-7702 Delegation
+
+https://eips.ethereum.org/EIPS/eip-7702[EIP-7702] lets EOAs delegate to smart contracts while keeping their original signing key. This creates a hybrid account that works like an EOA for signing but has smart contract features. Protocols don't need major changes to support EIP-7702 since they already handle both EOAs and smart contracts (see https://docs.openzeppelin.com/contracts/5.x/api/utils#SignatureChecker[SignatureChecker]).
+
+The signature verification stays compatible: delegated EOAs are treated as contracts using ERC-1271, making it easy to redelegate to a contract with ERC-1271 support with little overhead by reusing the validation mechanism of the account. 
+
+TIP: Learn more about delegating to an ERC-7702 account in our xref:eoa-delegation.adoc[EOA Delegation] section.
+
+=== ERC-7579 Modules
+
+Smart accounts have evolved to embrace modularity as a design principle, with popular implementations like https://erc7579.com/#supporters[Safe, Pimlico, Rhinestone, Etherspot and many others] agreeing on ERC-7579 as the standard for module interoperability. This standardization enables accounts to extend their functionality through external contracts while maintaining compatibility across different implementations.
+
+OpenZeppelin Contracts provides both the building blocks for creating ERC-7579-compliant modules and an xref:api:account.adoc#AccountERC7579[`AccountERC7579`] implementation that supports installing and managing these modules. 
+
+TIP: Learn more in our xref:account-modules.adoc[account modules] section.