Add support for ECDSA public keys in OpenSSH (RFC 4253) format

CHANGELOG.md

@@ -7,6 +7,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 [Unreleased][unreleased]
 -------------------------------------------------------------------------
 ### Changed
+- Add support for ECDSA public keys in RFC 4253 (OpenSSH) format [#244][244]
 - Renamed commandline script `jwt` to `jwt-cli` to avoid issues with the script clobbering the `jwt` module in some circumstances.
 - Better error messages when using an algorithm that requires the cryptography package, but it isn't available [#230][230]
 
@@ -129,3 +130,4 @@ rarely used. Users affected by this should upgrade to 3.3+.
 [182]: https://github.com/jpadilla/pyjwt/pull/182
 [183]: https://github.com/jpadilla/pyjwt/pull/183
 [213]: https://github.com/jpadilla/pyjwt/pull/214
+[244]: https://github.com/jpadilla/pyjwt/pull/244

jwt/algorithms.py

@@ -356,7 +356,10 @@ def prepare_key(self, key):
                 # a Signing Key or a Verifying Key, so we try
                 # the Verifying Key first.
                 try:
-                    key = load_pem_public_key(key, backend=default_backend())
+                    if key.startswith(b'ecdsa-sha2-'):
+                        key = load_ssh_public_key(key, backend=default_backend())
+                    else:
+                        key = load_pem_public_key(key, backend=default_backend())
                 except ValueError:
                     key = load_pem_private_key(key, password=None, backend=default_backend())
 

tests/keys/testkey_ec_ssh.pub

@@ -0,0 +1 @@
+ecdsa-sha2-nistp521 AAAAE2VjZHNhLXNoYTItbmlzdHA1MjEAAAAIbmlzdHA1MjEAAACFBAFZwnA8QCdL+TiQWBSHE0XsnRJBCFkb6c2DL7+ZfCFDk9khSYh3VrVOOQ1eIrO/oOm20Gp24dvP9XQS0f5B9bLQHgGFnkydPIMaNzPUNCop17F5uHOhtuFIhmOlh3lpTjyj2ten86cCetqN12kawnRs1/iu0wsGoVgk3os6yUAHvFMFGA==

tests/test_algorithms.py

@@ -375,6 +375,13 @@ def test_ec_should_accept_pem_private_key_bytes(self):
         with open(key_path('testkey_ec'), 'rb') as ec_key:
             algo.prepare_key(ec_key.read())
 
+    @pytest.mark.skipif(not has_crypto, reason='Not supported without cryptography library')
+    def test_ec_should_accept_ssh_public_key_bytes(self):
+        algo = ECAlgorithm(ECAlgorithm.SHA256)
+
+        with open(key_path('testkey_ec_ssh.pub'), 'r') as ec_key:
+            algo.prepare_key(ec_key.read())
+
     @pytest.mark.skipif(not has_crypto, reason='Not supported without cryptography library')
     def test_ec_verify_should_return_false_if_signature_invalid(self):
         algo = ECAlgorithm(ECAlgorithm.SHA256)