more test coverage for keys module, remove dead code

Author: tomato42

src/ecdsa/keys.py

@@ -1102,12 +1102,6 @@ def from_der(cls, string, hashfunc=sha1, valid_curve_encodings=None):
 
             curve = Curve.from_der(algorithm_identifier, valid_curve_encodings)
 
-            if empty != b"":
-                raise der.UnexpectedDER(
-                    "unexpected data after algorithm identifier: %s"
-                    % binascii.hexlify(empty)
-                )
-
             # Up next is an octet string containing an ECPrivateKey. Ignore
             # the optional "attributes" and "publicKey" fields that come after.
             s, _ = der.remove_octet_string(s)

src/ecdsa/test_keys.py

@@ -25,6 +25,8 @@
     encode_sequence,
     encode_oid,
     encode_bitstring,
+    encode_integer,
+    encode_octet_string,
 )
 from .util import (
     sigencode_string,
@@ -668,6 +670,34 @@ def test_ed25519_from_pem(self):
 
         self.assertEqual(sk, sk_str)
 
+    def test_ed25519_from_der_bad_alg_id_params(self):
+        der_str = encode_sequence(
+            encode_integer(1),
+            encode_sequence(encode_oid(*Ed25519.oid), encode_integer(1)),
+            encode_octet_string(encode_octet_string(b"A" * 32)),
+        )
+
+        with self.assertRaises(UnexpectedDER) as e:
+            SigningKey.from_der(der_str)
+
+        self.assertIn("Non NULL parameters", str(e.exception))
+
+    def test_ed25519_from_der_junk_after_priv_key(self):
+        der_str = encode_sequence(
+            encode_integer(1),
+            encode_sequence(
+                encode_oid(*Ed25519.oid),
+            ),
+            encode_octet_string(encode_octet_string(b"A" * 32) + b"B"),
+        )
+
+        with self.assertRaises(UnexpectedDER) as e:
+            SigningKey.from_der(der_str)
+
+        self.assertIn(
+            "trailing junk after the encoded private key", str(e.exception)
+        )
+
     def test_ed25519_sign(self):
         sk_str = SigningKey.from_string(
             b"\x34\xBA\xC7\xD1\x4E\xD4\xF1\xBC\x4F\x8C\x48\x3E\x0F\x19\x77\x4C"
@@ -774,6 +804,11 @@ def test_ed25519_to_and_from_pem(self):
 
         self.assertEqual(sk, decoded)
 
+    def test_ed25519_custom_entropy(self):
+        sk = SigningKey.generate(Ed25519, entropy=os.urandom)
+
+        self.assertIsNotNone(sk)
+
     def test_ed25519_from_secret_exponent(self):
         with self.assertRaises(ValueError) as e:
             SigningKey.from_secret_exponent(1234567890, curve=Ed25519)