fix: audit N-07

src/SsoAccount.sol

@@ -119,7 +119,7 @@ contract SsoAccount is
   /// @param _to The address to which the call is made.
   /// @param _value The value to send along with the call.
   /// @param _data The calldata to pass along with the call.
-  function _executeCall(address _to, uint128 _value, bytes calldata _data) internal {
+  function _executeCall(address _to, uint128 _value, bytes calldata _data) private {
     uint32 gas = Utils.safeCastToU32(gasleft());
     bool success;
 
@@ -192,7 +192,7 @@ contract SsoAccount is
   /// @param _signedHash The signed hash of the transaction.
   /// @param _transaction The transaction data.
   /// @return The magic value if the validation was successful and bytes4(0) otherwise.
-  function _validateTransaction(bytes32 _signedHash, Transaction calldata _transaction) internal returns (bytes4) {
+  function _validateTransaction(bytes32 _signedHash, Transaction calldata _transaction) private returns (bytes4) {
     // Run validation hooks
     bool hookSuccess = runValidationHooks(_signedHash, _transaction);
     if (!hookSuccess) {
@@ -222,7 +222,7 @@ contract SsoAccount is
   /// @dev Increments the nonce value in Nonce Holder system contract to ensure replay attack protection.
   /// @dev Reverts if the Nonce Holder stores different `_nonce` value from the expected one.
   /// @param _expectedNonce The nonce value expected for the account to be stored in the Nonce Holder.
-  function _incrementNonce(uint256 _expectedNonce) internal {
+  function _incrementNonce(uint256 _expectedNonce) private {
     // Allow-listing slither finding as the call's success is checked+revert within the fn
     // slither-disable-next-line unused-return
     SystemContractsCaller.systemCallWithPropagatedRevert(
@@ -235,7 +235,7 @@ contract SsoAccount is
 
   /// @dev Safely casts a uint256 to an address.
   /// @dev Revert if the value exceeds the maximum size for an address (160 bits).
-  function _safeCastToAddress(uint256 _value) internal pure returns (address) {
+  function _safeCastToAddress(uint256 _value) private pure returns (address) {
     require(_value <= type(uint160).max, "Overflow");
     return address(uint160(_value));
   }

src/libraries/SessionLib.sol

@@ -201,7 +201,7 @@ library SessionLib {
     CallSpec[] memory callPolicies,
     uint64[] memory periodIds,
     uint256 periodIdsOffset
-  ) internal returns (CallSpec memory) {
+  ) private returns (CallSpec memory) {
     CallSpec memory callPolicy;
     bool found = false;
 
@@ -344,7 +344,7 @@ library SessionLib {
     UsageLimit memory limit,
     UsageTracker storage tracker,
     address account
-  ) internal view returns (uint256) {
+  ) private view returns (uint256) {
     if (limit.limitType == LimitType.Unlimited) {
       // this might be still limited by `maxValuePerUse` or a constraint
       return type(uint256).max;

src/managers/HookManager.sol

@@ -98,7 +98,7 @@ abstract contract HookManager is IHookManager, SelfAuth {
     }
   }
 
-  function _addHook(address hook, bool isValidation, bytes calldata initData) internal {
+  function _addHook(address hook, bool isValidation, bytes calldata initData) private {
     if (!_supportsHook(hook, isValidation)) {
       revert Errors.HOOK_ERC165_FAIL(hook, isValidation);
     }
@@ -114,7 +114,7 @@ abstract contract HookManager is IHookManager, SelfAuth {
     emit HookAdded(hook);
   }
 
-  function _removeHook(address hook, bool isValidation) internal {
+  function _removeHook(address hook, bool isValidation) private {
     if (isValidation) {
       require(_validationHooks().remove(hook), "Hook not found");
     } else {

src/managers/OwnerManager.sol

@@ -37,13 +37,14 @@ abstract contract OwnerManager is IOwnerManager, SelfAuth {
     k1OwnerList = _k1Owners().values();
   }
 
+  // Should not be set to private as it is called from SsoAccount's initialize
   function _k1AddOwner(address addr) internal {
     require(_k1Owners().add(addr), "K1 owner already exists");
 
     emit K1OwnerAdded(addr);
   }
 
-  function _k1RemoveOwner(address addr) internal {
+  function _k1RemoveOwner(address addr) private {
     require(_k1Owners().remove(addr), "K1 owner not found");
 
     emit K1OwnerRemoved(addr);

src/managers/ValidatorManager.sol

@@ -54,6 +54,7 @@ abstract contract ValidatorManager is IValidatorManager, SelfAuth {
     validatorList = _moduleValidators().values();
   }
 
+  // Should not be set to private as it is called from SsoAccount's initialize
   function _addModuleValidator(address validator, bytes memory initData) internal {
     if (!_supportsModuleValidator(validator)) {
       revert Errors.VALIDATOR_ERC165_FAIL(validator);
@@ -65,7 +66,7 @@ abstract contract ValidatorManager is IValidatorManager, SelfAuth {
     emit ValidatorAdded(validator);
   }
 
-  function _removeModuleValidator(address validator) internal {
+  function _removeModuleValidator(address validator) private {
     require(_moduleValidators().remove(validator), "Validator not found");
 
     emit ValidatorRemoved(validator);

src/validators/SessionKeyValidator.sol

@@ -93,7 +93,7 @@ contract SessionKeyValidator is IModuleValidator {
 
   /// @notice creates a new session for an account, called by onInstall
   /// @param sessionData ABI-encoded session specification
-  function _addValidationKey(bytes calldata sessionData) internal returns (bool) {
+  function _addValidationKey(bytes calldata sessionData) private returns (bool) {
     SessionLib.SessionSpec memory sessionSpec = abi.decode(sessionData, (SessionLib.SessionSpec));
     createSession(sessionSpec);
     return true;

src/validators/WebAuthValidator.sol

@@ -150,7 +150,7 @@ contract WebAuthValidator is VerifierCaller, IModuleValidator {
   }
 
   /// @inheritdoc IERC165
-  function supportsInterface(bytes4 interfaceId) public pure override returns (bool) {
+  function supportsInterface(bytes4 interfaceId) external pure override returns (bool) {
     return
       interfaceId == type(IERC165).interfaceId ||
       interfaceId == type(IModuleValidator).interfaceId ||