1 files changed, 94 insertions, 0 deletions
diff --git a/tools/mcuboot/imgtool/keys/__init__.py b/tools/mcuboot/imgtool/keys/__init__.py
new file mode 100644
index 00000000..f25e2aae
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+++ b/tools/mcuboot/imgtool/keys/__init__.py
@@ -0,0 +1,94 @@
+# Copyright 2017 Linaro Limited
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Cryptographic key management for imgtool.
+"""
+
+from cryptography.hazmat.backends import default_backend
+from cryptography.hazmat.primitives import serialization
+from cryptography.hazmat.primitives.asymmetric.rsa import (
+    RSAPrivateKey, RSAPublicKey)
+from cryptography.hazmat.primitives.asymmetric.ec import (
+    EllipticCurvePrivateKey, EllipticCurvePublicKey)
+from cryptography.hazmat.primitives.asymmetric.ed25519 import (
+    Ed25519PrivateKey, Ed25519PublicKey)
+from cryptography.hazmat.primitives.asymmetric.x25519 import (
+    X25519PrivateKey, X25519PublicKey)
+
+from .rsa import RSA, RSAPublic, RSAUsageError, RSA_KEY_SIZES
+from .ecdsa import ECDSA256P1, ECDSA256P1Public, ECDSAUsageError
+from .ed25519 import Ed25519, Ed25519Public, Ed25519UsageError
+from .x25519 import X25519, X25519Public, X25519UsageError
+
+
+class PasswordRequired(Exception):
+    """Raised to indicate that the key is password protected, but a
+    password was not specified."""
+    pass
+
+
+def load(path, passwd=None):
+    """Try loading a key from the given path.  Returns None if the password wasn't specified."""
+    with open(path, 'rb') as f:
+        raw_pem = f.read()
+    try:
+        pk = serialization.load_pem_private_key(
+            raw_pem,
+            password=passwd,
+            backend=default_backend())
+    # Unfortunately, the crypto library raises unhelpful exceptions,
+    # so we have to look at the text.
+    except TypeError as e:
+        msg = str(e)
+        if "private key is encrypted" in msg:
+            return None
+        raise e
+    except ValueError:
+        # This seems to happen if the key is a public key, let's try
+        # loading it as a public key.
+        pk = serialization.load_pem_public_key(
+            raw_pem,
+            backend=default_backend())
+
+    if isinstance(pk, RSAPrivateKey):
+        if pk.key_size not in RSA_KEY_SIZES:
+            raise Exception("Unsupported RSA key size: " + pk.key_size)
+        return RSA(pk)
+    elif isinstance(pk, RSAPublicKey):
+        if pk.key_size not in RSA_KEY_SIZES:
+            raise Exception("Unsupported RSA key size: " + pk.key_size)
+        return RSAPublic(pk)
+    elif isinstance(pk, EllipticCurvePrivateKey):
+        if pk.curve.name != 'secp256r1':
+            raise Exception("Unsupported EC curve: " + pk.curve.name)
+        if pk.key_size != 256:
+            raise Exception("Unsupported EC size: " + pk.key_size)
+        return ECDSA256P1(pk)
+    elif isinstance(pk, EllipticCurvePublicKey):
+        if pk.curve.name != 'secp256r1':
+            raise Exception("Unsupported EC curve: " + pk.curve.name)
+        if pk.key_size != 256:
+            raise Exception("Unsupported EC size: " + pk.key_size)
+        return ECDSA256P1Public(pk)
+    elif isinstance(pk, Ed25519PrivateKey):
+        return Ed25519(pk)
+    elif isinstance(pk, Ed25519PublicKey):
+        return Ed25519Public(pk)
+    elif isinstance(pk, X25519PrivateKey):
+        return X25519(pk)
+    elif isinstance(pk, X25519PublicKey):
+        return X25519Public(pk)
+    else:
+        raise Exception("Unknown key type: " + str(type(pk)))