Added test cases for NIST P-384 and 521. Fixed handling of key sizes which aren't divisibly by 8

2 files changed, 56 insertions, 5 deletions

diff --git a/src/cryptography/hazmat/primitives/serialization.py b/src/cryptography/hazmat/primitives/serialization.py
index b95ac1cd..dad419fe 100644
--- a/src/cryptography/hazmat/primitives/serialization.py
+++ b/src/cryptography/hazmat/primitives/serialization.py
@@ -102,16 +102,18 @@ def _load_ssh_ecdsa_public_key(expected_key_type, decoded_data, backend):
     elif curve_name == b"nistp521":
         curve = ec.SECP521R1()
 
-    if len(data) != 1 + 2 * (curve.key_size // 8):
-        raise ValueError("Malformed key bytes")
-
     if six.indexbytes(data, 0) != 4:
         raise NotImplementedError(
             "Compressed elliptic curve points are not supported"
         )
 
-    x = _int_from_bytes(data[1:1 + curve.key_size // 8], byteorder='big')
-    y = _int_from_bytes(data[1 + curve.key_size // 8:], byteorder='big')
+    # key_size is in bits, and sometimes it's not evenly divisible by 8, so we
+    # add 7 to round up the number of bytes.
+    if len(data) != 1 + 2 * ((curve.key_size + 7) // 8):
+        raise ValueError("Malformed key bytes")
+
+    x = _int_from_bytes(data[1:1 + (curve.key_size + 7) // 8], byteorder='big')
+    y = _int_from_bytes(data[1 + (curve.key_size + 7) // 8:], byteorder='big')
     return ec.EllipticCurvePublicNumbers(x, y, curve).public_key(backend)
 
 
diff --git a/tests/hazmat/primitives/test_serialization.py b/tests/hazmat/primitives/test_serialization.py
index 2434ee45..fdd88a82 100644
--- a/tests/hazmat/primitives/test_serialization.py
+++ b/tests/hazmat/primitives/test_serialization.py
@@ -812,6 +812,55 @@ class TestECDSASSHSerialization(object):
             expected_x, expected_y, ec.SECP256R1()
         )
 
+    def test_load_ssh_public_key_ecdsa_nist_p384(self, backend):
+        _skip_curve_unsupported(backend, ec.SECP384R1())
+        ssh_key = (
+            b"ecdsa-sha2-nistp384 AAAAE2VjZHNhLXNoYTItbmlzdHAzODQAAAAIbmlzdHAz"
+            b"ODQAAABhBMzucOm9wbwg4iMr5QL0ya0XNQGXpw4wM5f12E3tWhdcrzyGHyel71t1"
+            b"4bvF9JZ2/WIuSxUr33XDl8jYo+lMQ5N7Vanc7f7i3AR1YydatL3wQfZStQ1I3rBa"
+            b"qQtRSEU8Tg== root@cloud-server-01"
+        )
+        key = load_ssh_public_key(ssh_key, backend)
+
+        expected_x = int(
+            "31541830871345183397582554827482786756220448716666815789487537666"
+            "592636882822352575507883817901562613492450642523901", 10
+        )
+        expected_y = int(
+            "15111413269431823234030344298767984698884955023183354737123929430"
+            "995703524272335782455051101616329050844273733614670", 10
+        )
+
+        assert key.public_numbers() == ec.EllipticCurvePublicNumbers(
+            expected_x, expected_y, ec.SECP384R1()
+        )
+
+    def test_load_ssh_public_key_ecdsa_nist_p521(self, backend):
+        _skip_curve_unsupported(backend, ec.SECP521R1())
+        ssh_key = (
+            b"ecdsa-sha2-nistp521 AAAAE2VjZHNhLXNoYTItbmlzdHA1MjEAAAAIbmlzdHA1"
+            b"MjEAAACFBAGTrRhMSEgF6Ni+PXNz+5fjS4lw3ypUILVVQ0Av+0hQxOx+MyozELon"
+            b"I8NKbrbBjijEs1GuImsmkTmWsMXS1j2A7wB4Kseh7W9KA9IZJ1+TMrzWUEwvOOXi"
+            b"wT23pbaWWXG4NaM7vssWfZBnvz3S174TCXnJ+DSccvWBFnKP0KchzLKxbg== "
+            b"root@cloud-server-01"
+        )
+        key = load_ssh_public_key(ssh_key, backend)
+
+        expected_x = int(
+            "54124123120178189598842622575230904027376313369742467279346415219"
+            "77809037378785192537810367028427387173980786968395921877911964629"
+            "142163122798974160187785455", 10
+        )
+        expected_y = int(
+            "16111775122845033200938694062381820957441843014849125660011303579"
+            "15284560361402515564433711416776946492019498546572162801954089916"
+            "006665939539407104638103918", 10
+        )
+
+        assert key.public_numbers() == ec.EllipticCurvePublicNumbers(
+            expected_x, expected_y, ec.SECP521R1()
+        )
+
     def test_load_ssh_public_key_ecdsa_nist_p256_trailing_data(self, backend):
         ssh_key = (
             b"ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAy"