chore: Moved jwt file to openedx.core.lib

openedx/core/lib/jwt.py

@@ -0,0 +1,91 @@
+"""
+JWT Token handling and signing functions.
+"""
+
+import json
+from time import time
+
+from django.conf import settings
+from jwkest import Expired, Invalid, MissingKey, jwk
+from jwkest.jws import JWS
+
+
+def create_jwt(lms_user_id, expires_in_seconds, additional_token_claims, now=None):
+    """
+    Produce an encoded JWT (string) indicating some temporary permission for the indicated user.
+
+    What permission that is must be encoded in additional_claims.
+    Arguments:
+        lms_user_id (int): LMS user ID this token is being generated for
+        expires_in_seconds (int): Time to token expiry, specified in seconds.
+        additional_token_claims (dict): Additional claims to include in the token.
+        now(int): optional now value for testing
+    """
+    now = now or int(time())
+
+    payload = {
+        'lms_user_id': lms_user_id,
+        'exp': now + expires_in_seconds,
+        'iat': now,
+        'iss': settings.TOKEN_SIGNING['JWT_ISSUER'],
+        'version': settings.TOKEN_SIGNING['JWT_SUPPORTED_VERSION'],
+    }
+    payload.update(additional_token_claims)
+    return _encode_and_sign(payload)
+
+
+def _encode_and_sign(payload):
+    """
+    Encode and sign the provided payload.
+
+    The signing key and algorithm are pulled from settings.
+    """
+    keys = jwk.KEYS()
+
+    serialized_keypair = json.loads(settings.TOKEN_SIGNING['JWT_PRIVATE_SIGNING_JWK'])
+    keys.add(serialized_keypair)
+    algorithm = settings.TOKEN_SIGNING['JWT_SIGNING_ALGORITHM']
+
+    data = json.dumps(payload)
+    jws = JWS(data, alg=algorithm)
+    return jws.sign_compact(keys=keys)
+
+
+def unpack_jwt(token, lms_user_id, now=None):
+    """
+    Unpack and verify an encoded JWT.
+
+    Validate the user and expiration.
+
+    Arguments:
+        token (string): The token to be unpacked and verified.
+        lms_user_id (int): LMS user ID this token should match with.
+        now (int): Optional now value for testing.
+
+    Returns a valid, decoded json payload (string).
+    """
+    now = now or int(time())
+    payload = _unpack_and_verify(token)
+
+    if "lms_user_id" not in payload:
+        raise MissingKey("LMS user id is missing")
+    if "exp" not in payload:
+        raise MissingKey("Expiration is missing")
+    if payload["lms_user_id"] != lms_user_id:
+        raise Invalid("User does not match")
+    if payload["exp"] < now:
+        raise Expired("Token is expired")
+
+    return payload
+
+
+def _unpack_and_verify(token):
+    """
+    Unpack and verify the provided token.
+
+    The signing key and algorithm are pulled from settings.
+    """
+    keys = jwk.KEYS()
+    keys.load_jwks(settings.TOKEN_SIGNING['JWT_PUBLIC_SIGNING_JWK_SET'])
+    decoded = JWS().verify_compact(token.encode('utf-8'), keys)
+    return decoded

openedx/core/lib/tests/test_jwt.py

@@ -0,0 +1,126 @@
+"""
+Tests for token handling
+"""
+import unittest
+
+from django.conf import settings
+from jwkest import BadSignature, Expired, Invalid, MissingKey, jwk
+from jwkest.jws import JWS
+
+from openedx.core.lib.jwt import _encode_and_sign, create_jwt, unpack_jwt
+
+
+test_user_id = 121
+invalid_test_user_id = 120
+test_timeout = 60
+test_now = 1661432902
+test_claims = {"foo": "bar", "baz": "quux", "meaning": 42}
+expected_full_token = {
+    "lms_user_id": test_user_id,
+    "iat": 1661432902,
+    "exp": 1661432902 + 60,
+    "iss": "token-test-issuer",  # these lines from test_settings.py
+    "version": "1.2.0",  # these lines from test_settings.py
+}
+
+
+class TestSign(unittest.TestCase):
+    """
+    Tests for JWT creation and signing.
+    """
+
+    def test_create_jwt(self):
+        token = create_jwt(test_user_id, test_timeout, {}, test_now)
+
+        decoded = _verify_jwt(token)
+        self.assertEqual(expected_full_token, decoded)
+
+    def test_create_jwt_with_claims(self):
+        token = create_jwt(test_user_id, test_timeout, test_claims, test_now)
+
+        expected_token_with_claims = expected_full_token.copy()
+        expected_token_with_claims.update(test_claims)
+
+        decoded = _verify_jwt(token)
+        self.assertEqual(expected_token_with_claims, decoded)
+
+    def test_malformed_token(self):
+        token = create_jwt(test_user_id, test_timeout, test_claims, test_now)
+        token = token + "a"
+
+        expected_token_with_claims = expected_full_token.copy()
+        expected_token_with_claims.update(test_claims)
+
+        with self.assertRaises(BadSignature):
+            _verify_jwt(token)
+
+
+def _verify_jwt(jwt_token):
+    """
+    Helper function which verifies the signature and decodes the token
+    from string back to claims form
+    """
+    keys = jwk.KEYS()
+    keys.load_jwks(settings.TOKEN_SIGNING['JWT_PUBLIC_SIGNING_JWK_SET'])
+    decoded = JWS().verify_compact(jwt_token.encode('utf-8'), keys)
+    return decoded
+
+
+class TestUnpack(unittest.TestCase):
+    """
+    Tests for JWT unpacking.
+    """
+
+    def test_unpack_jwt(self):
+        token = create_jwt(test_user_id, test_timeout, {}, test_now)
+        decoded = unpack_jwt(token, test_user_id, test_now)
+
+        self.assertEqual(expected_full_token, decoded)
+
+    def test_unpack_jwt_with_claims(self):
+        token = create_jwt(test_user_id, test_timeout, test_claims, test_now)
+
+        expected_token_with_claims = expected_full_token.copy()
+        expected_token_with_claims.update(test_claims)
+
+        decoded = unpack_jwt(token, test_user_id, test_now)
+
+        self.assertEqual(expected_token_with_claims, decoded)
+
+    def test_malformed_token(self):
+        token = create_jwt(test_user_id, test_timeout, test_claims, test_now)
+        token = token + "a"
+
+        expected_token_with_claims = expected_full_token.copy()
+        expected_token_with_claims.update(test_claims)
+
+        with self.assertRaises(BadSignature):
+            unpack_jwt(token, test_user_id, test_now)
+
+    def test_unpack_token_with_invalid_user(self):
+        token = create_jwt(invalid_test_user_id, test_timeout, {}, test_now)
+
+        with self.assertRaises(Invalid):
+            unpack_jwt(token, test_user_id, test_now)
+
+    def test_unpack_expired_token(self):
+        token = create_jwt(test_user_id, test_timeout, {}, test_now)
+
+        with self.assertRaises(Expired):
+            unpack_jwt(token, test_user_id, test_now + test_timeout + 1)
+
+    def test_missing_expired_lms_user_id(self):
+        payload = expected_full_token.copy()
+        del payload['lms_user_id']
+        token = _encode_and_sign(payload)
+
+        with self.assertRaises(MissingKey):
+            unpack_jwt(token, test_user_id, test_now)
+
+    def test_missing_expired_key(self):
+        payload = expected_full_token.copy()
+        del payload['exp']
+        token = _encode_and_sign(payload)
+
+        with self.assertRaises(MissingKey):
+            unpack_jwt(token, test_user_id, test_now)