added stringUtils contract and test

contracts/TestStringUtils.sol

@@ -0,0 +1,14 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.13;
+
+import { StringUtils } from "./libraries/stringUtils.sol";
+
+contract TestStringUtils {
+ function test(bytes calldata data) public pure returns (bytes memory result) {
+ string memory key = abi.decode(
+ data,
+ (string)
+ );
+ result = StringUtils.hexToBytes(key);
+ }
+}

contracts/libraries/stringUtils.sol

@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.13;
+
+import { strings } from "./strings.sol";
+
+// Extracted from https://github.com/zkemail/email-wallet-sdk/blob/main/src/helpers/StringUtils.sol
+library StringUtils {
+ using strings for *;
+
+ function hexToBytes32(string calldata hexStr) public pure returns (bytes32 result) {
+ require(hexStr.toSlice().startsWith("0x".toSlice()), "invalid hex prefix");
+ hexStr = hexStr[2:];
+ require(bytes(hexStr).length == 64, "invalid hex string length");
+ uint256[] memory ints = hex2Ints(hexStr);
+ uint256 sum = 0;
+ for (uint256 i = 0; i < 32; i++) {
+ sum = (256 * sum + ints[i]);
+ }
+ return bytes32(sum);
+ }
+
+ function hexToBytes(string calldata hexStr) public pure returns (bytes memory) {
+ require(hexStr.toSlice().startsWith("0x".toSlice()), "invalid hex prefix");
+ string memory hexStrNoPrefix = hexStr[2:];
+ bytes memory hexBytes = bytes(hexStrNoPrefix);
+ require(hexBytes.length % 2 == 0, "invalid hex string length");
+
+ bytes memory result = new bytes(hexBytes.length / 2);
+
+ for (uint256 i = 0; i < hexBytes.length / 2; i++) {
+ result[i] = bytes1(
+ (hexChar2Int(hexBytes[2 * i]) << 4) + hexChar2Int(hexBytes[2 * i + 1])
+ );
+ }
+ return result;
+ }
+
+ function hex2Ints(string memory hexStr) private pure returns (uint256[] memory) {
+ uint256[] memory result = new uint256[](bytes(hexStr).length / 2);
+ for (uint256 i = 0; i < result.length; i++) {
+ result[i] =
+ 16 * hexChar2Int(bytes(hexStr)[2 * i]) + hexChar2Int(bytes(hexStr)[2 * i + 1]);
+ }
+ return result;
+ }
+
+ function hexChar2Int(bytes1 char) private pure returns (uint8) {
+ uint8 charInt = uint8(char);
+ if (charInt >= 48 && charInt <= 57) {
+ return charInt - 48; // '0' - '9'
+ } else if (charInt >= 65 && charInt <= 70) {
+ return charInt - 55; // 'A' - 'F'
+ } else if (charInt >= 97 && charInt <= 102) {
+ return charInt - 87; // 'a' - 'f'
+ } else {
+ revert("invalid hex char");
+ }
+ }
+}