Add support for wasm32-pyodide

src/argon2/_password_hasher.py

@@ -3,11 +3,12 @@
 from __future__ import annotations
 
 import os
+import platform
 
 from typing import ClassVar, Literal
 
 from ._utils import Parameters, _check_types, extract_parameters
-from .exceptions import InvalidHashError
+from .exceptions import InvalidHashError, UnsupportedParamsError
 from .low_level import Type, hash_secret, verify_secret
 from .profiles import RFC_9106_LOW_MEMORY
 
@@ -16,7 +17,9 @@
 DEFAULT_HASH_LENGTH = RFC_9106_LOW_MEMORY.hash_len
 DEFAULT_TIME_COST = RFC_9106_LOW_MEMORY.time_cost
 DEFAULT_MEMORY_COST = RFC_9106_LOW_MEMORY.memory_cost
-DEFAULT_PARALLELISM = RFC_9106_LOW_MEMORY.parallelism
+DEFAULT_PARALLELISM = (
+    1 if platform.machine() == "wasm32" else RFC_9106_LOW_MEMORY.parallelism
+)
 
 
 def _ensure_bytes(s: bytes | str, encoding: str) -> bytes:
@@ -106,8 +109,7 @@ def __init__(
         if e:
             raise TypeError(e)
 
-        # Cache a Parameters object for check_needs_rehash.
-        self._parameters = Parameters(
+        params = Parameters(
             type=type,
             version=19,
             salt_len=salt_len,
@@ -116,6 +118,12 @@ def __init__(
             memory_cost=memory_cost,
             parallelism=parallelism,
         )
+        # verify params before accepting
+        if platform.machine() == "wasm32" and parallelism != 1:
+            raise UnsupportedParamsError
+
+        # Cache a Parameters object for check_needs_rehash.
+        self._parameters = params
         self.encoding = encoding
 
     @classmethod
@@ -128,6 +136,9 @@ def from_parameters(cls, params: Parameters) -> PasswordHasher:
 
         .. versionadded:: 21.2.0
         """
+        # verify params before accepting
+        if platform.machine() == "wasm32" and params.parallelism != 1:
+            raise UnsupportedParamsError
         ph = cls()
         ph._parameters = params
 

src/argon2/exceptions.py

@@ -46,6 +46,14 @@ class InvalidHashError(ValueError):
     """
 
 
+class UnsupportedParamsError(ValueError):
+    """
+    Raised if the current platform doesn not support the parameters.
+
+    Eg. In Wasm32, parallelism must be set to 1.
+    """
+
+
 InvalidHash = InvalidHashError
 """
 Deprecated alias for :class:`InvalidHashError`.

tests/test_password_hasher.py

@@ -1,10 +1,17 @@
 # SPDX-License-Identifier: MIT
 
+from unittest import mock
+
 import pytest
 
 from argon2 import PasswordHasher, Type, extract_parameters, profiles
 from argon2._password_hasher import _ensure_bytes
-from argon2.exceptions import InvalidHash, InvalidHashError
+from argon2._utils import Parameters
+from argon2.exceptions import (
+    InvalidHash,
+    InvalidHashError,
+    UnsupportedParamsError,
+)
 
 
 class TestEnsureBytes:
@@ -151,3 +158,21 @@ def test_type_is_configurable(self):
         assert Type.I is ph.type is ph._parameters.type
         assert Type.I is extract_parameters(ph.hash("foo")).type
         assert ph.check_needs_rehash(default_hash)
+
+    def test_params_on_wasm32(self):
+        """
+        Should fail if on wasm32 and parallelism > 1
+        """
+        with mock.patch("platform.machine", return_value="wasm32"):
+            with pytest.raises(UnsupportedParamsError):
+                PasswordHasher(parallelism=2)
+
+            # last param is parallelism so it should fail
+            params = Parameters(Type.I, 2, 8, 8, 3, 256, 8)
+            with pytest.raises(UnsupportedParamsError):
+                ph = PasswordHasher.from_parameters(params)
+
+            # test normal execution
+            ph = PasswordHasher(parallelism=1)
+            hash = ph.hash("hello")
+            assert ph.verify(hash, "hello") is True