Update doc, small code improvement

CHANGELOG.md

@@ -2,7 +2,10 @@
 
 Please follow <https://changelog.md/> conventions.
 
+## 2.5.0
 
+- Change Solidity version to 0.8.27 (latest)
+- Small improvement in documentation
 
 ## 2.5.0-rc.0 - 20240809
 

FAQ.md

@@ -3,6 +3,40 @@
 This FAQ is intended to developers familiar with smart contracts
 development.
 
+## Cross-chain bridge support
+
+> With which bridge can the CMTAT be used?
+
+We will analyze the three main bridges: [CCIP](https://chain.link/cross-chain) by Chainlink, [LayerZero](https://layerzero.network) and [AxelarNetwork](https://www.axelar.network)
+
+Generally, in term of implementation, it depends of the model to handle cross-chain token transfer. There are three main models: Burn & Mint, Lock & Mint, Lock & Unlock
+
+To use one of these models, you must implement in the token the functions required and used by the bridge (typically burn and mint). The model "lock and lock" is a little different from the first two models because it does not in principle require any particular implementation.
+
+For example the interface for CCIP is available here: [github.com/smartcontractkit/ccip - ERC20/IBurnMintERC20.sol](https://github.com/smartcontractkit/ccip/blob/948882675ad1c6604d4b911071fc3881148abe66/contracts/src/v0.8/shared/token/ERC20/IBurnMintERC20.sol)
+
+Axelar Network has also a similar behavior and requirement to create what they call a custom interchain token: https://docs.axelar.dev/dev/send-tokens/interchain-tokens/create-token#create-a-custom-interchain-token
+
+We haven't done any testing but in principle the functions `burnFrom`and `mint` are available and compatible with the last CMTAT version, see [github.com/CMTA/CMTAT/blob/master/contracts/interfaces/ICCIPToken.sol](https://github.com/CMTA/CMTAT/blob/master/contracts/interfaces/ICCIPToken.sol).
+
+For the public burn function, unfortunately, we currently have a reason argument in the function which is not compatible with bridges because their burn function only have two arguments (account and value): [github.com/CMTA/CMTAT - wrapper/core/ERC20BurnModule.sol#L32](https://github.com/CMTA/CMTAT/blob/master/contracts/modules/wrapper/core/ERC20BurnModule.sol#L32)
+
+### Chainlink CCIP
+
+For chainlink, the difficulty is that for the moment only tokens whitelisted by chainlink (e.g USDC) can use the bridge, which is not the case for Axelar Network.
+
+The ERC-20 interface for CCIP is available here: [github.com/smartcontractkit/ccip - ERC20/IBurnMintERC20.sol](https://github.com/smartcontractkit/ccip/blob/948882675ad1c6604d4b911071fc3881148abe66/contracts/src/v0.8/shared/token/ERC20/IBurnMintERC20.sol)
+
+### LayerZero
+
+There are two possibilities to use LayerZero with a CMTAT:
+
+The first one is to add a module inside CMTAT to include the Omnichain Fungible Token (OFT) Standard; see  [github.com/LayerZero-Labs - OFT.sol](https://github.com/LayerZero-Labs/LayerZero-v2/blob/main/packages/layerzero-v2/evm/oapp/contracts/oft/OFT.sol)
+
+The second possibility is to deploy an OFT Adapter to act as an intermediary lockbox for the token.
+
+More information in LayerZero documentation: [docs.layerzero.network/v2/developers/evm/oft/quickstart](
+
 ## Toolkit support
 
 > Which is the main development tool you use ?

README.md

@@ -1,5 +1,3 @@
-
-
 # CMTA Token 
 
 > To use the CMTAT, we recommend the latest audited version, from the [Releases](https://github.com/CMTA/CMTAT/releases) page. Currently, it is the version [v2.3.0](https://github.com/CMTA/CMTAT/releases/tag/v2.3.0)
@@ -113,9 +111,9 @@ Generally, these modules are not required to be compliant with the CMTA specific
 | Name           | Documentation                                                | Main File                                                    |
 | -------------- | ------------------------------------------------------------ | ------------------------------------------------------------ |
 | MetaTxModule   | [metatx.md](doc/modules/presentation/extensions/metatx.md)   | [MetaTxModule.sol](./contracts/modules/wrapper/extensions/MetaTxModule.sol) |
-| SnapshotModule | [snapshot.md](doc/modules/presentation/extensions/snapshot.md) | [SnapshotModule.sol](./contracts/modules/wrapper/extensions/SnapshotModule.sol) |
-| DebtModule     | <Todo>                                                       | [DebtModule.sol](./contracts/modules/wrapper/extensions/DebtModule.sol) |
-| DocumentModue  | <Todo>                                                       | [Document.sol](./contracts/modules/wrapper/extensions/DocumentModule.sol) |
+| SnapshotModule | [snapshot.md](doc/modules/presentation/extensions/snapshot.md) | [ERC20SnapshotModule.sol](./contracts/modules/wrapper/extensions/ERC20SnapshotModule.sol) |
+| DebtModule     | [debt.md](doc/modules/presentation/extensions/debt.md)       | [DebtModule.sol](./contracts/modules/wrapper/extensions/DebtModule.sol) |
+| DocumentModue  | [document.md](doc/modules/presentation/extensions/document.md) | [Document.sol](./contracts/modules/wrapper/extensions/DocumentModule.sol) |
 
 ##### Security
 
@@ -139,7 +137,7 @@ The `RuleEngine` is an external contract used to apply transfer restriction to t
 
 This contract is defined in the `ValidationModule`.
 
-An example of RuleEngine is also available on [Github](https://github.com/CMTA/RuleEngine).
+An example of RuleEngine is also available on [GitHub](https://github.com/CMTA/RuleEngine).
 
 Here is the list of the different version available for each CMTAT version.
 
@@ -164,6 +162,8 @@ Before each transfer, the CMTAT calls the function `operateOnTransfer` which is
 
 #### AuthorizationEngine
 
+> Warning: this engine may be deleted in the future
+
 The `AuthorizationEngine` is an external contract to add supplementary check on the functions `grantRole` and `revokeRole`from the CMTAT.
 
 This contract is managed in the `AuthorizationModule`.
@@ -190,7 +190,11 @@ Use an external contract provides two advantages:
 - Reduce code size of CMTAT, which is near of the maximal size limit 
 - Allow to manage this information for several different tokens  (CMTAT or not).
 
-Currently, there is no implementation of a DebtEngine available
+Here is the list of the different version available for each CMTAT version.
+
+| Name                     | DebtEngine                                                   |
+| ------------------------ | ------------------------------------------------------------ |
+| CMTAT v2.5.0 (unaudited) | [DebtEngine v0.2.0](https://github.com/CMTA/DebtEngine/releases/tag/v0.2.0) |
 
 #### DocumentEngine (IERC-1643)
 
@@ -218,14 +222,18 @@ Use an external contract provides two advantages:
 - Reduce code size of CMTAT, which is near of the maximal size limit 
 - Allow to manage documents for several different tokens  (CMTAT or not).
 
-Currently, there is no implementation of a DocumentEngine available
+Here is the list of the different version available for each CMTAT version.
+
+| Name                     | DocumentEngine                                               |
+| ------------------------ | ------------------------------------------------------------ |
+| CMTAT v2.5.0 (unaudited) | [DocumentEngine v0.3.0](https://github.com/CMTA/DocumentEngine/releases/tag/v0.3.0) |
 
 ## Deployment model 
 
 | Model                       | Contract                                             |
 | --------------------------- | ---------------------------------------------------- |
 | Standalone                  | [CMTAT_STANDALONE](./contracts/CMTAT_STANDALONE.sol) |
-| Transparent ou Beacon Proxy | [CMTAT_PROXY](./contracts/CMTAT_PROXY.sol)           |
+| Transparent or Beacon Proxy | [CMTAT_PROXY](./contracts/CMTAT_PROXY.sol)           |
 | UUPS Proxy                  | [CMTAT_PROXY_UUPS](./contracts/CMTAT_PROXY_UUPS.sol) |
 
 
@@ -247,8 +255,6 @@ Please see the OpenZeppelin [Upgrades plugins](https://docs.openzeppelin.com/upg
 
 Note that deployment via a proxy is not mandatory, but is recommended by CMTA.
 
-
-
 ### Factory
 
 Factory contracts are available to deploy the CMTAT with a beacon proxy, a transparent proxy or an UUPS proxy.
@@ -358,11 +364,14 @@ CMTA providers further documentation describing the CMTAT framework in a platfor
 - [Taurus - Security Token Standards: A Closer Look at CMTAT](https://www.taurushq.com/blog/security-token-standards-a-closer-look-at-cmtat/)
 - [Taurus - Equity Tokenization: How to Pay Dividend On-Chain Using CMTAT](https://www.taurushq.com/blog/equity-tokenization-how-to-pay-dividend-on-chain-using-cmtat/)
 - [Taurus - Token Transfer Management: How to Apply Restrictions with CMTAT and ERC-1404](https://www.taurushq.com/blog/token-transfer-management-how-to-apply-restrictions-with-cmtat-and-erc-1404/)
+- [Taurus - Addressing the Privacy and Compliance Challenge in Public Blockchain Token Transactions](https://www.taurushq.com/blog/enhancing-token-transaction-privacy-on-public-blockchains-while-ensuring-compliance/)
 
 ## Others implementations
 Two versions are available for the blockchain [Tezos](https://tezos.com)
 - [CMTAT FA2](https://github.com/CMTA/CMTAT-Tezos-FA2) Official version written in SmartPy
 - [@ligo/cmtat](https://github.com/ligolang/CMTAT-Ligo/) Unofficial version written in Ligo
+  - See also [Tokenization of securities on Tezos by Frank Hillard](https://medium.com/@frank.hillard_62931/tokenization-of-securities-on-tezos-2e3c3e90fc5a)
+
 
 ## Contract size
 

contracts/deployment/CMTAT_BEACON_FACTORY.sol

@@ -2,10 +2,9 @@
 pragma solidity ^0.8.20;
 
 import "@openzeppelin/contracts/proxy/beacon/BeaconProxy.sol";
-
+import '@openzeppelin/contracts/utils/Create2.sol';
 import '@openzeppelin/contracts/proxy/beacon/UpgradeableBeacon.sol';
 import "../CMTAT_PROXY.sol";
-import "../modules/CMTAT_BASE.sol";
 import "./libraries/CMTATFactoryRoot.sol";
 
 

contracts/deployment/CMTAT_TP_FACTORY.sol

@@ -3,7 +3,6 @@ pragma solidity ^0.8.20;
 
 import "@openzeppelin/contracts/proxy/transparent/TransparentUpgradeableProxy.sol";
 import "../CMTAT_PROXY.sol";
-import "../libraries/FactoryErrors.sol";
 import '@openzeppelin/contracts/utils/Create2.sol';
 import "./libraries/CMTATFactoryInvariant.sol";
 import "./libraries/CMTATFactoryBase.sol";

contracts/deployment/CMTAT_UUPS_FACTORY.sol

@@ -3,9 +3,7 @@ pragma solidity ^0.8.20;
 
 import "@openzeppelin/contracts/proxy/ERC1967/ERC1967Proxy.sol";
 import "../CMTAT_PROXY_UUPS.sol";
-import "../libraries/FactoryErrors.sol";
 import '@openzeppelin/contracts/utils/Create2.sol';
-import '@openzeppelin/contracts/access/AccessControl.sol';
 import "./libraries/CMTATFactoryInvariant.sol";
 import "./libraries/CMTATFactoryBase.sol";
 /**

contracts/deployment/libraries/CMTATFactoryBase.sol

@@ -1,7 +1,6 @@
 //SPDX-License-Identifier: MPL-2.0
 pragma solidity ^0.8.20;
 
-import "@openzeppelin/contracts/proxy/transparent/TransparentUpgradeableProxy.sol";
 import "./CMTATFactoryRoot.sol";
 
 /**

contracts/deployment/libraries/CMTATFactoryRoot.sol

@@ -1,10 +1,7 @@
 //SPDX-License-Identifier: MPL-2.0
 pragma solidity ^0.8.20;
 
-import "@openzeppelin/contracts/proxy/transparent/TransparentUpgradeableProxy.sol";
-import "../../CMTAT_PROXY.sol";
 import "../../libraries/FactoryErrors.sol";
-import '@openzeppelin/contracts/utils/Create2.sol';
 import '@openzeppelin/contracts/access/AccessControl.sol';
 import "./CMTATFactoryInvariant.sol";
 /**
@@ -15,7 +12,7 @@ abstract contract CMTATFactoryRoot is AccessControl, CMTATFactoryInvariant {
     /* ============ State Variables ============ */
     // Public
     address[] public cmtatsList;
-    bool public useCustomSalt;
+    bool immutable public useCustomSalt;
     uint256 public cmtatCounterId;
     /// mapping
     mapping(uint256 => address) internal cmtats;

contracts/libraries/Errors.sol

@@ -53,9 +53,6 @@ library Errors {
     // DebtModule
     error CMTAT_DebtModule_SameValue();
 
-    // BaseModule
-    error CMTAT_BaseModule_SameValue();
-
     // ValidationModule
     error CMTAT_ValidationModule_SameValue();
 

contracts/modules/wrapper/core/BaseModule.sol

@@ -2,9 +2,7 @@
 
 pragma solidity ^0.8.20;
 
-// required OZ imports here
 import "../../security/AuthorizationModule.sol";
-import "../../../libraries/Errors.sol";
 
 abstract contract BaseModule is AuthorizationModule {
     /* ============ State Variables ============ */