├── package.json
├── .gitignore
├── hardhat.config.js
├── README.md
└── contracts
    └── Main.sol


/package.json:
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1 | {
2 |   "name": "hardhat-project"
3 | }
4 | 


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/.gitignore:
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 1 | node_modules
 2 | .env
 3 | coverage
 4 | coverage.json
 5 | typechain
 6 | typechain-types
 7 | 
 8 | # Hardhat files
 9 | cache
10 | artifacts
11 | 
12 | 


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/hardhat.config.js:
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1 | require("@nomicfoundation/hardhat-toolbox");
2 | 
3 | /** @type import('hardhat/config').HardhatUserConfig */
4 | module.exports = {
5 |   solidity: "^0.8.9",
6 | };
7 | 


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/README.md:
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 1 | Smart contracts custom methods
 2 | 
 3 |  
 4 | mint 
 5 | 
 6 | Parameters: 
 7 | 
 8 | uint256 amount: The number of tokens to mint. 
 9 | 
10 | bytes32 _hash: Hash of the message to be signed. 
11 | 
12 | uint8 _v: Recovery byte of the signature. 
13 | 
14 | bytes32 _r: First 32 bytes of the signature. 
15 | 
16 | bytes32 _s: Second 32 bytes of the signature. 
17 | 
18 | uint256 deadline: Deadline after which the signature is not valid. 
19 | 
20 | Access Control: Can only be called by the contract owner. 
21 | 
22 | 
23 | Functionality: 
24 | 
25 | Validates the mint amount, hash, and signature. 
26 | 
27 | Increments ownerNounce. 
28 | 
29 | Mints the specified amount of tokens to the sender's address. 
30 | 
31 | 
32 | 
33 | 
34 | burn 
35 | 
36 | Parameters: 
37 | 
38 | uint256 amount: The number of tokens to burn. 
39 | 
40 | Access Control: Can be called by any token holder. 
41 |  
42 | 


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/contracts/Main.sol:
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 1 | // SPDX-License-Identifier: MIT
 2 | pragma solidity ^0.8.9;
 3 | 
 4 | import "@openzeppelin/contracts/token/ERC20/extensions/draft-ERC20Permit.sol";
 5 | import "@openzeppelin/contracts/access/Ownable.sol";
 6 | import "@openzeppelin/contracts/utils/math/SafeMath.sol";
 7 | 
 8 | contract Diam is Ownable, ERC20Permit {
 9 |     using SafeMath for uint256;
10 | 
11 |     uint256 public ownerNounce;
12 | 
13 |     constructor() ERC20("DIAM", "DIAM") ERC20Permit("DIAM") {}
14 | 
15 |     //DW03 - zero amount request
16 |     //DW091 - Invalid hash
17 |     //DW02 - unauthorized
18 |     function mint(
19 |         uint256 amount,
20 |         bytes32 _hash,
21 |         uint8 _v,
22 |         bytes32 _r,
23 |         bytes32 _s,
24 |         uint256 deadline
25 |     ) external {
26 |         require(amount > 0, "DW03");
27 |         require(block.timestamp <= deadline, "DW092");
28 |         require(
29 |             keccak256(
30 |                 abi.encodePacked(
31 |                     msg.sender,
32 |                     amount,
33 |                     ownerNounce,
34 |                     block.chainid,
35 |                     deadline,
36 |                     address(this)
37 |                 )
38 |             ) == _hash,
39 |             "DW091"
40 |         );
41 | 
42 |         bytes32 messageDigest = keccak256(
43 |             abi.encodePacked(
44 |                 "\x19Ethereum Signed Message:\n32",
45 |                 keccak256(
46 |                     abi.encodePacked(
47 |                         msg.sender,
48 |                         amount,
49 |                         ownerNounce,
50 |                         block.chainid,
51 |                         deadline,
52 |                         address(this)
53 |                     )
54 |                 )
55 |             )
56 |         );
57 | 
58 |         address signer = ECDSA.recover(messageDigest, _v, _r, _s);
59 | 
60 |         require(signer == owner(), "DW02");
61 | 
62 |         ownerNounce++;
63 | 
64 |         _mint(_msgSender(), amount);
65 |     }
66 | 
67 |     function burn(uint256 amount) external {
68 |         _burn(msg.sender, amount);
69 |     }
70 | }
71 | 


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