Add support for Ed25519 / EdDSA, with unit tests (#455)

5 files changed, 173 insertions, 0 deletions

diff --git a/jwt/algorithms.py b/jwt/algorithms.py
index 293a470..5e65d9f 100644
--- a/jwt/algorithms.py
+++ b/jwt/algorithms.py
@@ -43,6 +43,7 @@ try:
     has_crypto = True
 except ImportError:
     has_crypto = False
+    has_ed25519 = False
 
 requires_cryptography = set(
     [
@@ -56,6 +57,7 @@ requires_cryptography = set(
         "PS256",
         "PS384",
         "PS512",
+        "EdDSA",
     ]
 )
 
@@ -86,8 +88,18 @@ def get_default_algorithms():
                 "PS256": RSAPSSAlgorithm(RSAPSSAlgorithm.SHA256),
                 "PS384": RSAPSSAlgorithm(RSAPSSAlgorithm.SHA384),
                 "PS512": RSAPSSAlgorithm(RSAPSSAlgorithm.SHA512),
+                
             }
         )
+        # Older versions of the `cryptography` libraries may not have Ed25519 available.
+        # Needs a minimum of version 2.6
+        try:
+            from jwt.contrib.algorithms.py_ed25519 import Ed25519Algorithm
+            default_algorithms.update({
+                "EdDSA":   Ed25519Algorithm(),
+            })
+        except ImportError:
+            pass
 
     return default_algorithms
 
diff --git a/jwt/contrib/algorithms/py_ed25519.py b/jwt/contrib/algorithms/py_ed25519.py
new file mode 100644
index 0000000..6e761d5
--- /dev/null
+++ b/jwt/contrib/algorithms/py_ed25519.py
@@ -0,0 +1,71 @@
+"""
+Implementation of Ed25519 using ``cryptography`` (as of Version 2.6 released in February 2019)
+"""
+
+import cryptography.exceptions
+from cryptography.hazmat.backends import default_backend
+from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey, Ed25519PublicKey
+from cryptography.hazmat.primitives.serialization import load_pem_public_key, load_pem_private_key, load_ssh_public_key
+
+from jwt.algorithms import Algorithm
+from jwt.compat import string_types, text_type
+
+
+class Ed25519Algorithm(Algorithm):
+    """
+    Performs signing and verification operations using Ed25519
+
+    This class requires ``cryptography>=2.6`` to be installed.
+    """
+    
+    def __init__(self, **kwargs):
+        pass
+    
+    def prepare_key(self, key):
+        
+        if isinstance(key, (Ed25519PrivateKey, Ed25519PublicKey)):
+            return key
+        
+        if isinstance(key, string_types):
+            if isinstance(key, text_type):
+                key = key.encode("utf-8")
+            str_key = key.decode('utf-8')
+            
+            if '-----BEGIN PUBLIC' in str_key:
+                return load_pem_public_key(key, backend=default_backend())
+            if '-----BEGIN PRIVATE' in str_key:
+                return load_pem_private_key(key, password=None, backend=default_backend())
+            if str_key[0:4] == 'ssh-':
+                return load_ssh_public_key(key, backend=default_backend())
+        
+        raise TypeError("Expecting a PEM-formatted or OpenSSH key.")
+    
+    def sign(self, msg, key):
+        """
+        Sign a message ``msg`` using the Ed25519 private key ``key``
+        :param str|bytes msg: Message to sign
+        :param Ed25519PrivateKey key: A :class:`.Ed25519PrivateKey` instance
+        :return bytes signature: The signature, as bytes
+        """
+        msg = bytes(msg, 'utf-8') if type(msg) is not bytes else msg
+        return key.sign(msg)
+    
+    def verify(self, msg, key, sig):
+        """
+        Verify a given ``msg`` against a signature ``sig`` using the Ed25519 key ``key``
+        
+        :param str|bytes sig: Ed25519 signature to check ``msg`` against
+        :param str|bytes msg: Message to sign
+        :param Ed25519PrivateKey|Ed25519PublicKey key: A private or public Ed25519 key instance
+        :return bool verified: True if signature is valid, False if not.
+        """
+        try:
+            msg = bytes(msg, 'utf-8') if type(msg) is not bytes else msg
+            sig = bytes(sig, 'utf-8') if type(sig) is not bytes else sig
+
+            if isinstance(key, Ed25519PrivateKey):
+                key = key.public_key()
+            key.verify(sig, msg)
+            return True   # If no exception was raised, the signature is valid.
+        except cryptography.exceptions.InvalidSignature:
+            return False
diff --git a/tests/contrib/test_algorithms.py b/tests/contrib/test_algorithms.py
index 4a1550b..35825c0 100644
--- a/tests/contrib/test_algorithms.py
+++ b/tests/contrib/test_algorithms.py
@@ -1,4 +1,5 @@
 import base64
+import warnings
 
 import pytest
 
@@ -20,6 +21,13 @@ try:
 except ImportError:
     has_ecdsa = False
 
+try:
+    from jwt.contrib.algorithms.py_ed25519 import Ed25519Algorithm
+    
+    has_ed25519 = True
+except ImportError as e:
+    has_ed25519 = False
+
 
 @pytest.mark.skipif(
     not has_pycrypto, reason="Not supported without PyCrypto library"
@@ -212,3 +220,81 @@ class TestEcdsaAlgorithms:
             jwt_pub_key_second = algo.prepare_key(jwt_pub_key_first)
 
         assert jwt_pub_key_first == jwt_pub_key_second
+
+
+@pytest.mark.skipif(
+    not has_ed25519, reason="Not supported without cryptography>=2.6 library"
+)
+class TestEd25519Algorithms:
+    hello_world_sig = 'Qxa47mk/azzUgmY2StAOguAd4P7YBLpyCfU3JdbaiWnXM4o4WibXwmIHvNYgN3frtE2fcyd8OYEaOiD/KiwkCg=='
+    hello_world = force_bytes('Hello World!')
+    
+    def test_ed25519_should_reject_non_string_key(self):
+        algo = Ed25519Algorithm()
+        
+        with pytest.raises(TypeError):
+            algo.prepare_key(None)
+
+        with open(key_path("testkey_ed25519"), "r") as keyfile:
+            jwt_key = algo.prepare_key(keyfile.read())
+
+        with open(key_path("testkey_ed25519.pub"), "r") as keyfile:
+            jwt_pub_key = algo.prepare_key(keyfile.read())
+
+    def test_ed25519_should_accept_unicode_key(self):
+        algo = Ed25519Algorithm()
+
+        with open(key_path("testkey_ed25519"), "r") as ec_key:
+            algo.prepare_key(force_unicode(ec_key.read()))
+
+    def test_ed25519_sign_should_generate_correct_signature_value(self):
+        algo = Ed25519Algorithm()
+
+        jwt_message = self.hello_world
+    
+        expected_sig = base64.b64decode(force_bytes(self.hello_world_sig))
+
+        with open(key_path("testkey_ed25519"), "r") as keyfile:
+            jwt_key = algo.prepare_key(keyfile.read())
+
+        with open(key_path("testkey_ed25519.pub"), "r") as keyfile:
+            jwt_pub_key = algo.prepare_key(keyfile.read())
+    
+        algo.sign(jwt_message, jwt_key)
+        result = algo.verify(jwt_message, jwt_pub_key, expected_sig)
+        assert result
+
+    def test_ed25519_verify_should_return_false_if_signature_invalid(self):
+        algo = Ed25519Algorithm()
+
+        jwt_message = self.hello_world
+        jwt_sig = base64.b64decode(force_bytes(self.hello_world_sig))
+    
+        jwt_sig += force_bytes("123")  # Signature is now invalid
+
+        with open(key_path("testkey_ed25519.pub"), "r") as keyfile:
+            jwt_pub_key = algo.prepare_key(keyfile.read())
+    
+        result = algo.verify(jwt_message, jwt_pub_key, jwt_sig)
+        assert not result
+
+    def test_ed25519_verify_should_return_true_if_signature_valid(self):
+        algo = Ed25519Algorithm()
+
+        jwt_message = self.hello_world
+        jwt_sig = base64.b64decode(force_bytes(self.hello_world_sig))
+
+        with open(key_path("testkey_ed25519.pub"), "r") as keyfile:
+            jwt_pub_key = algo.prepare_key(keyfile.read())
+    
+        result = algo.verify(jwt_message, jwt_pub_key, jwt_sig)
+        assert result
+
+    def test_ed25519_prepare_key_should_be_idempotent(self):
+        algo = Ed25519Algorithm()
+
+        with open(key_path("testkey_ed25519.pub"), "r") as keyfile:
+            jwt_pub_key_first = algo.prepare_key(keyfile.read())
+            jwt_pub_key_second = algo.prepare_key(jwt_pub_key_first)
+    
+        assert jwt_pub_key_first == jwt_pub_key_second
diff --git a/tests/keys/testkey_ed25519 b/tests/keys/testkey_ed25519
new file mode 100644
index 0000000..6863f17
--- /dev/null
+++ b/tests/keys/testkey_ed25519
@@ -0,0 +1,3 @@
+-----BEGIN PRIVATE KEY-----
+MC4CAQAwBQYDK2VwBCIEIBy9N4xfv/9qOiKrxwRKeGfO5ab6lSukKHbuC5vaJ1Mg
+-----END PRIVATE KEY-----
diff --git a/tests/keys/testkey_ed25519.pub b/tests/keys/testkey_ed25519.pub
new file mode 100644
index 0000000..13c80c7
--- /dev/null
+++ b/tests/keys/testkey_ed25519.pub
@@ -0,0 +1 @@
+ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIC4pK2dePGgctIAsh0H/tmUrLzx2Vc4Ltc8TN9nfuChG
\ No newline at end of file