Initial commit

Initial commit.

bootloader/mcuboot/scripts/imgtool/keys/__init__.py

@@ -0,0 +1,105 @@
+# Copyright 2017 Linaro Limited
+# Copyright 2023 Arm Limited
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+# 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,
+                    ECDSA384P1, ECDSA384P1Public, 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 not in ('secp256r1', 'secp384r1'):
+            raise Exception("Unsupported EC curve: " + pk.curve.name)
+        if pk.key_size not in (256, 384):
+            raise Exception("Unsupported EC size: " + pk.key_size)
+        if pk.curve.name == 'secp256r1':
+            return ECDSA256P1(pk)
+        elif pk.curve.name == 'secp384r1':
+            return ECDSA384P1(pk)
+    elif isinstance(pk, EllipticCurvePublicKey):
+        if pk.curve.name not in ('secp256r1', 'secp384r1'):
+            raise Exception("Unsupported EC curve: " + pk.curve.name)
+        if pk.key_size not in (256, 384):
+            raise Exception("Unsupported EC size: " + pk.key_size)
+        if pk.curve.name == 'secp256r1':
+            return ECDSA256P1Public(pk)
+        elif pk.curve.name == 'secp384r1':
+            return ECDSA384P1Public(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)))

bootloader/mcuboot/scripts/imgtool/keys/ecdsa.py

@@ -0,0 +1,289 @@
+"""
+ECDSA key management
+"""
+
+# SPDX-License-Identifier: Apache-2.0
+import os.path
+import hashlib
+
+from cryptography.hazmat.backends import default_backend
+from cryptography.hazmat.primitives import serialization
+from cryptography.hazmat.primitives.asymmetric import ec
+from cryptography.hazmat.primitives.hashes import SHA256, SHA384
+
+from .general import KeyClass
+from .privatebytes import PrivateBytesMixin
+
+
+class ECDSAUsageError(Exception):
+    pass
+
+
+class ECDSAPublicKey(KeyClass):
+    """
+    Wrapper around an ECDSA public key.
+    """
+    def __init__(self, key):
+        self.key = key
+
+    def _unsupported(self, name):
+        raise ECDSAUsageError("Operation {} requires private key".format(name))
+
+    def _get_public(self):
+        return self.key
+
+    def get_public_bytes(self):
+        # The key is embedded into MBUboot in "SubjectPublicKeyInfo" format
+        return self._get_public().public_bytes(
+                encoding=serialization.Encoding.DER,
+                format=serialization.PublicFormat.SubjectPublicKeyInfo)
+
+    def get_public_pem(self):
+        return self._get_public().public_bytes(
+                encoding=serialization.Encoding.PEM,
+                format=serialization.PublicFormat.SubjectPublicKeyInfo)
+
+    def get_private_bytes(self, minimal, format):
+        self._unsupported('get_private_bytes')
+
+    def export_private(self, path, passwd=None):
+        self._unsupported('export_private')
+
+    def export_public(self, path):
+        """Write the public key to the given file."""
+        pem = self._get_public().public_bytes(
+                encoding=serialization.Encoding.PEM,
+                format=serialization.PublicFormat.SubjectPublicKeyInfo)
+        with open(path, 'wb') as f:
+            f.write(pem)
+
+
+class ECDSAPrivateKey(PrivateBytesMixin):
+    """
+    Wrapper around an ECDSA private key.
+    """
+    def __init__(self, key):
+        self.key = key
+
+    def _get_public(self):
+        return self.key.public_key()
+
+    def _build_minimal_ecdsa_privkey(self, der, format):
+        '''
+        Builds a new DER that only includes the EC private key, removing the
+        public key that is added as an "optional" BITSTRING.
+        '''
+
+        if format == serialization.PrivateFormat.OpenSSH:
+            print(os.path.basename(__file__) +
+                  ': Warning: --minimal is supported only for PKCS8 '
+                  'or TraditionalOpenSSL formats')
+            return bytearray(der)
+
+        EXCEPTION_TEXT = "Error parsing ecdsa key. Please submit an issue!"
+        if format == serialization.PrivateFormat.PKCS8:
+            offset_PUB = 68  # where the context specific TLV starts (tag 0xA1)
+            if der[offset_PUB] != 0xa1:
+                raise ECDSAUsageError(EXCEPTION_TEXT)
+            len_PUB = der[offset_PUB + 1] + 2  # + 2 for 0xA1 0x44 bytes
+            b = bytearray(der[:offset_PUB])  # remove the TLV with the PUB key
+            offset_SEQ = 29
+            if b[offset_SEQ] != 0x30:
+                raise ECDSAUsageError(EXCEPTION_TEXT)
+            b[offset_SEQ + 1] -= len_PUB
+            offset_OCT_STR = 27
+            if b[offset_OCT_STR] != 0x04:
+                raise ECDSAUsageError(EXCEPTION_TEXT)
+            b[offset_OCT_STR + 1] -= len_PUB
+            if b[0] != 0x30 or b[1] != 0x81:
+                raise ECDSAUsageError(EXCEPTION_TEXT)
+            # as b[1] has bit7 set, the length is on b[2]
+            b[2] -= len_PUB
+            if b[2] < 0x80:
+                del(b[1])
+
+        elif format == serialization.PrivateFormat.TraditionalOpenSSL:
+            offset_PUB = 51
+            if der[offset_PUB] != 0xA1:
+                raise ECDSAUsageError(EXCEPTION_TEXT)
+            len_PUB = der[offset_PUB + 1] + 2
+            b = bytearray(der[0:offset_PUB])
+            b[1] -= len_PUB
+
+        return b
+
+    _VALID_FORMATS = {
+        'pkcs8': serialization.PrivateFormat.PKCS8,
+        'openssl': serialization.PrivateFormat.TraditionalOpenSSL
+    }
+    _DEFAULT_FORMAT = 'pkcs8'
+
+    def get_private_bytes(self, minimal, format):
+        format, priv = self._get_private_bytes(minimal,
+                                               format, ECDSAUsageError)
+        if minimal:
+            priv = self._build_minimal_ecdsa_privkey(
+                priv, self._VALID_FORMATS[format])
+        return priv
+
+    def export_private(self, path, passwd=None):
+        """Write the private key to the given file, protecting it with '
+          'the optional password."""
+        if passwd is None:
+            enc = serialization.NoEncryption()
+        else:
+            enc = serialization.BestAvailableEncryption(passwd)
+        pem = self.key.private_bytes(
+                encoding=serialization.Encoding.PEM,
+                format=serialization.PrivateFormat.PKCS8,
+                encryption_algorithm=enc)
+        with open(path, 'wb') as f:
+            f.write(pem)
+
+
+class ECDSA256P1Public(ECDSAPublicKey):
+    """
+    Wrapper around an ECDSA (p256) public key.
+    """
+    def __init__(self, key):
+        super().__init__(key)
+        self.key = key
+
+    def shortname(self):
+        return "ecdsa"
+
+    def sig_type(self):
+        return "ECDSA256_SHA256"
+
+    def sig_tlv(self):
+        return "ECDSASIG"
+
+    def sig_len(self):
+        # Early versions of MCUboot (< v1.5.0) required ECDSA
+        # signatures to be padded to 72 bytes.  Because the DER
+        # encoding is done with signed integers, the size of the
+        # signature will vary depending on whether the high bit is set
+        # in each value.  This padding was done in a
+        # not-easily-reversible way (by just adding zeros).
+        #
+        # The signing code no longer requires this padding, and newer
+        # versions of MCUboot don't require it.  But, continue to
+        # return the total length so that the padding can be done if
+        # requested.
+        return 72
+
+    def verify(self, signature, payload):
+        # strip possible paddings added during sign
+        signature = signature[:signature[1] + 2]
+        k = self.key
+        if isinstance(self.key, ec.EllipticCurvePrivateKey):
+            k = self.key.public_key()
+        return k.verify(signature=signature, data=payload,
+                        signature_algorithm=ec.ECDSA(SHA256()))
+
+
+class ECDSA256P1(ECDSAPrivateKey, ECDSA256P1Public):
+    """
+    Wrapper around an ECDSA (p256) private key.
+    """
+    def __init__(self, key):
+        super().__init__(key)
+        self.key = key
+        self.pad_sig = False
+
+    @staticmethod
+    def generate():
+        pk = ec.generate_private_key(
+                ec.SECP256R1(),
+                backend=default_backend())
+        return ECDSA256P1(pk)
+
+    def raw_sign(self, payload):
+        """Return the actual signature"""
+        return self.key.sign(
+                data=payload,
+                signature_algorithm=ec.ECDSA(SHA256()))
+
+    def sign(self, payload):
+        sig = self.raw_sign(payload)
+        if self.pad_sig:
+            # To make fixed length, pad with one or two zeros.
+            sig += b'\000' * (self.sig_len() - len(sig))
+            return sig
+        else:
+            return sig
+
+
+class ECDSA384P1Public(ECDSAPublicKey):
+    """
+    Wrapper around an ECDSA (p384) public key.
+    """
+    def __init__(self, key):
+        super().__init__(key)
+        self.key = key
+
+    def shortname(self):
+        return "ecdsap384"
+
+    def sig_type(self):
+        return "ECDSA384_SHA384"
+
+    def sig_tlv(self):
+        return "ECDSASIG"
+
+    def sig_len(self):
+        # Early versions of MCUboot (< v1.5.0) required ECDSA
+        # signatures to be padded to a fixed length.  Because the DER
+        # encoding is done with signed integers, the size of the
+        # signature will vary depending on whether the high bit is set
+        # in each value.  This padding was done in a
+        # not-easily-reversible way (by just adding zeros).
+        #
+        # The signing code no longer requires this padding, and newer
+        # versions of MCUboot don't require it.  But, continue to
+        # return the total length so that the padding can be done if
+        # requested.
+        return 103
+
+    def verify(self, signature, payload):
+        # strip possible paddings added during sign
+        signature = signature[:signature[1] + 2]
+        k = self.key
+        if isinstance(self.key, ec.EllipticCurvePrivateKey):
+            k = self.key.public_key()
+        return k.verify(signature=signature, data=payload,
+                        signature_algorithm=ec.ECDSA(SHA384()))
+
+
+class ECDSA384P1(ECDSAPrivateKey, ECDSA384P1Public):
+    """
+    Wrapper around an ECDSA (p384) private key.
+    """
+
+    def __init__(self, key):
+        """key should be an instance of EllipticCurvePrivateKey"""
+        super().__init__(key)
+        self.key = key
+        self.pad_sig = False
+
+    @staticmethod
+    def generate():
+        pk = ec.generate_private_key(
+                ec.SECP384R1(),
+                backend=default_backend())
+        return ECDSA384P1(pk)
+
+    def raw_sign(self, payload):
+        """Return the actual signature"""
+        return self.key.sign(
+                data=payload,
+                signature_algorithm=ec.ECDSA(SHA384()))
+
+    def sign(self, payload):
+        sig = self.raw_sign(payload)
+        if self.pad_sig:
+            # To make fixed length, pad with one or two zeros.
+            sig += b'\000' * (self.sig_len() - len(sig))
+            return sig
+        else:
+            return sig

bootloader/mcuboot/scripts/imgtool/keys/ecdsa_test.py

@@ -0,0 +1,120 @@
+"""
+Tests for ECDSA keys
+"""
+
+# SPDX-License-Identifier: Apache-2.0
+
+import io
+import os.path
+import sys
+import tempfile
+import unittest
+
+from cryptography.exceptions import InvalidSignature
+from cryptography.hazmat.primitives.asymmetric import ec
+from cryptography.hazmat.primitives.hashes import SHA256
+
+sys.path.insert(0, os.path.abspath(os.path.join(os.path.dirname(__file__), '../..')))
+
+from imgtool.keys import load, ECDSA256P1, ECDSAUsageError
+
+class EcKeyGeneration(unittest.TestCase):
+
+    def setUp(self):
+        self.test_dir = tempfile.TemporaryDirectory()
+
+    def tname(self, base):
+        return os.path.join(self.test_dir.name, base)
+
+    def tearDown(self):
+        self.test_dir.cleanup()
+
+    def test_keygen(self):
+        name1 = self.tname("keygen.pem")
+        k = ECDSA256P1.generate()
+        k.export_private(name1, b'secret')
+
+        self.assertIsNone(load(name1))
+
+        k2 = load(name1, b'secret')
+
+        pubname = self.tname('keygen-pub.pem')
+        k2.export_public(pubname)
+        pk2 = load(pubname)
+
+        # We should be able to export the public key from the loaded
+        # public key, but not the private key.
+        pk2.export_public(self.tname('keygen-pub2.pem'))
+        self.assertRaises(ECDSAUsageError,
+                pk2.export_private, self.tname('keygen-priv2.pem'))
+
+    def test_emit(self):
+        """Basic sanity check on the code emitters."""
+        k = ECDSA256P1.generate()
+
+        pubpem = io.StringIO()
+        k.emit_public_pem(pubpem)
+        self.assertIn("BEGIN PUBLIC KEY", pubpem.getvalue())
+        self.assertIn("END PUBLIC KEY", pubpem.getvalue())
+
+        ccode = io.StringIO()
+        k.emit_c_public(ccode)
+        self.assertIn("ecdsa_pub_key", ccode.getvalue())
+        self.assertIn("ecdsa_pub_key_len", ccode.getvalue())
+
+        hashccode = io.StringIO()
+        k.emit_c_public_hash(hashccode)
+        self.assertIn("ecdsa_pub_key_hash", hashccode.getvalue())
+        self.assertIn("ecdsa_pub_key_hash_len", hashccode.getvalue())
+
+        rustcode = io.StringIO()
+        k.emit_rust_public(rustcode)
+        self.assertIn("ECDSA_PUB_KEY", rustcode.getvalue())
+
+        # raw data - bytes
+        pubraw = io.BytesIO()
+        k.emit_raw_public(pubraw)
+        self.assertTrue(len(pubraw.getvalue()) > 0)
+
+        hashraw = io.BytesIO()
+        k.emit_raw_public_hash(hashraw)
+        self.assertTrue(len(hashraw.getvalue()) > 0)
+
+    def test_emit_pub(self):
+        """Basic sanity check on the code emitters, from public key."""
+        pubname = self.tname("public.pem")
+        k = ECDSA256P1.generate()
+        k.export_public(pubname)
+
+        k2 = load(pubname)
+
+        ccode = io.StringIO()
+        k2.emit_c_public(ccode)
+        self.assertIn("ecdsa_pub_key", ccode.getvalue())
+        self.assertIn("ecdsa_pub_key_len", ccode.getvalue())
+
+        rustcode = io.StringIO()
+        k2.emit_rust_public(rustcode)
+        self.assertIn("ECDSA_PUB_KEY", rustcode.getvalue())
+
+    def test_sig(self):
+        k = ECDSA256P1.generate()
+        buf = b'This is the message'
+        sig = k.raw_sign(buf)
+
+        # The code doesn't have any verification, so verify this
+        # manually.
+        k.key.public_key().verify(
+                signature=sig,
+                data=buf,
+                signature_algorithm=ec.ECDSA(SHA256()))
+
+        # Modify the message to make sure the signature fails.
+        self.assertRaises(InvalidSignature,
+                k.key.public_key().verify,
+                signature=sig,
+                data=b'This is thE message',
+                signature_algorithm=ec.ECDSA(SHA256()))
+
+if __name__ == '__main__':
+    unittest.main()

bootloader/mcuboot/scripts/imgtool/keys/ed25519.py

@@ -0,0 +1,111 @@
+"""
+ED25519 key management
+"""
+
+# SPDX-License-Identifier: Apache-2.0
+
+from cryptography.hazmat.primitives import serialization
+from cryptography.hazmat.primitives.asymmetric import ed25519
+
+from .general import KeyClass
+
+
+class Ed25519UsageError(Exception):
+    pass
+
+
+class Ed25519Public(KeyClass):
+    def __init__(self, key):
+        self.key = key
+
+    def shortname(self):
+        return "ed25519"
+
+    def _unsupported(self, name):
+        raise Ed25519UsageError("Operation {} requires private key".format(name))
+
+    def _get_public(self):
+        return self.key
+
+    def get_public_bytes(self):
+        # The key is embedded into MBUboot in "SubjectPublicKeyInfo" format
+        return self._get_public().public_bytes(
+                encoding=serialization.Encoding.DER,
+                format=serialization.PublicFormat.SubjectPublicKeyInfo)
+
+    def get_public_pem(self):
+        return self._get_public().public_bytes(
+            encoding=serialization.Encoding.PEM,
+            format=serialization.PublicFormat.SubjectPublicKeyInfo)
+
+    def get_private_bytes(self, minimal, format):
+        self._unsupported('get_private_bytes')
+
+    def export_private(self, path, passwd=None):
+        self._unsupported('export_private')
+
+    def export_public(self, path):
+        """Write the public key to the given file."""
+        pem = self._get_public().public_bytes(
+                encoding=serialization.Encoding.PEM,
+                format=serialization.PublicFormat.SubjectPublicKeyInfo)
+        with open(path, 'wb') as f:
+            f.write(pem)
+
+    def sig_type(self):
+        return "ED25519"
+
+    def sig_tlv(self):
+        return "ED25519"
+
+    def sig_len(self):
+        return 64
+
+    def verify_digest(self, signature, digest):
+        """Verify that signature is valid for given digest"""
+        k = self.key
+        if isinstance(self.key, ed25519.Ed25519PrivateKey):
+            k = self.key.public_key()
+        return k.verify(signature=signature, data=digest)
+
+
+class Ed25519(Ed25519Public):
+    """
+    Wrapper around an ED25519 private key.
+    """
+
+    def __init__(self, key):
+        """key should be an instance of EllipticCurvePrivateKey"""
+        self.key = key
+
+    @staticmethod
+    def generate():
+        pk = ed25519.Ed25519PrivateKey.generate()
+        return Ed25519(pk)
+
+    def _get_public(self):
+        return self.key.public_key()
+
+    def get_private_bytes(self, minimal, format):
+        raise Ed25519UsageError("Operation not supported with {} keys".format(
+            self.shortname()))
+
+    def export_private(self, path, passwd=None):
+        """
+        Write the private key to the given file, protecting it with the
+        optional password.
+        """
+        if passwd is None:
+            enc = serialization.NoEncryption()
+        else:
+            enc = serialization.BestAvailableEncryption(passwd)
+        pem = self.key.private_bytes(
+                encoding=serialization.Encoding.PEM,
+                format=serialization.PrivateFormat.PKCS8,
+                encryption_algorithm=enc)
+        with open(path, 'wb') as f:
+            f.write(pem)
+
+    def sign_digest(self, digest):
+        """Return the actual signature"""
+        return self.key.sign(data=digest)

bootloader/mcuboot/scripts/imgtool/keys/ed25519_test.py

@@ -0,0 +1,124 @@
+"""
+Tests for ECDSA keys
+"""
+
+# SPDX-License-Identifier: Apache-2.0
+
+import hashlib
+import io
+import os.path
+import sys
+import tempfile
+import unittest
+
+from cryptography.exceptions import InvalidSignature
+from cryptography.hazmat.primitives.asymmetric import ed25519
+
+sys.path.insert(0, os.path.abspath(os.path.join(os.path.dirname(__file__), '../..')))
+
+from imgtool.keys import load, Ed25519, Ed25519UsageError
+
+
+class Ed25519KeyGeneration(unittest.TestCase):
+
+    def setUp(self):
+        self.test_dir = tempfile.TemporaryDirectory()
+
+    def tname(self, base):
+        return os.path.join(self.test_dir.name, base)
+
+    def tearDown(self):
+        self.test_dir.cleanup()
+
+    def test_keygen(self):
+        name1 = self.tname("keygen.pem")
+        k = Ed25519.generate()
+        k.export_private(name1, b'secret')
+
+        self.assertIsNone(load(name1))
+
+        k2 = load(name1, b'secret')
+
+        pubname = self.tname('keygen-pub.pem')
+        k2.export_public(pubname)
+        pk2 = load(pubname)
+
+        # We should be able to export the public key from the loaded
+        # public key, but not the private key.
+        pk2.export_public(self.tname('keygen-pub2.pem'))
+        self.assertRaises(Ed25519UsageError,
+                          pk2.export_private, self.tname('keygen-priv2.pem'))
+
+    def test_emit(self):
+        """Basic sanity check on the code emitters."""
+        k = Ed25519.generate()
+
+        pubpem = io.StringIO()
+        k.emit_public_pem(pubpem)
+        self.assertIn("BEGIN PUBLIC KEY", pubpem.getvalue())
+        self.assertIn("END PUBLIC KEY", pubpem.getvalue())
+
+        ccode = io.StringIO()
+        k.emit_c_public(ccode)
+        self.assertIn("ed25519_pub_key", ccode.getvalue())
+        self.assertIn("ed25519_pub_key_len", ccode.getvalue())
+
+        hashccode = io.StringIO()
+        k.emit_c_public_hash(hashccode)
+        self.assertIn("ed25519_pub_key_hash", hashccode.getvalue())
+        self.assertIn("ed25519_pub_key_hash_len", hashccode.getvalue())
+
+        rustcode = io.StringIO()
+        k.emit_rust_public(rustcode)
+        self.assertIn("ED25519_PUB_KEY", rustcode.getvalue())
+
+        # raw data - bytes
+        pubraw = io.BytesIO()
+        k.emit_raw_public(pubraw)
+        self.assertTrue(len(pubraw.getvalue()) > 0)
+
+        hashraw = io.BytesIO()
+        k.emit_raw_public_hash(hashraw)
+        self.assertTrue(len(hashraw.getvalue()) > 0)
+
+    def test_emit_pub(self):
+        """Basic sanity check on the code emitters, from public key."""
+        pubname = self.tname("public.pem")
+        k = Ed25519.generate()
+        k.export_public(pubname)
+
+        k2 = load(pubname)
+
+        ccode = io.StringIO()
+        k2.emit_c_public(ccode)
+        self.assertIn("ed25519_pub_key", ccode.getvalue())
+        self.assertIn("ed25519_pub_key_len", ccode.getvalue())
+
+        rustcode = io.StringIO()
+        k2.emit_rust_public(rustcode)
+        self.assertIn("ED25519_PUB_KEY", rustcode.getvalue())
+
+    def test_sig(self):
+        k = Ed25519.generate()
+        buf = b'This is the message'
+        sha = hashlib.sha256()
+        sha.update(buf)
+        digest = sha.digest()
+        sig = k.sign_digest(digest)
+
+        # The code doesn't have any verification, so verify this
+        # manually.
+        k.key.public_key().verify(signature=sig, data=digest)
+
+        # Modify the message to make sure the signature fails.
+        sha = hashlib.sha256()
+        sha.update(b'This is thE message')
+        new_digest = sha.digest()
+        self.assertRaises(InvalidSignature,
+                          k.key.public_key().verify,
+                          signature=sig,
+                          data=new_digest)
+
+
+if __name__ == '__main__':
+    unittest.main()

bootloader/mcuboot/scripts/imgtool/keys/general.py

@@ -0,0 +1,115 @@
+"""General key class."""
+
+# SPDX-License-Identifier: Apache-2.0
+
+import binascii
+import io
+import os
+import sys
+from cryptography.hazmat.primitives.hashes import Hash, SHA256
+
+AUTOGEN_MESSAGE = "/* Autogenerated by imgtool.py, do not edit. */"
+
+
+class FileHandler(object):
+    def __init__(self, file, *args, **kwargs):
+        self.file_in = file
+        self.args = args
+        self.kwargs = kwargs
+
+    def __enter__(self):
+        if isinstance(self.file_in, (str, bytes, os.PathLike)):
+            self.file = open(self.file_in, *self.args, **self.kwargs)
+        else:
+            self.file = self.file_in
+        return self.file
+
+    def __exit__(self, *args):
+        if self.file != self.file_in:
+            self.file.close()
+
+
+class KeyClass(object):
+    def _emit(self, header, trailer, encoded_bytes, indent, file=sys.stdout,
+              len_format=None):
+        with FileHandler(file, 'w') as file:
+            self._emit_to_output(header, trailer, encoded_bytes, indent,
+                                     file, len_format)
+
+    def _emit_to_output(self, header, trailer, encoded_bytes, indent, file,
+                        len_format):
+        print(AUTOGEN_MESSAGE, file=file)
+        print(header, end='', file=file)
+        for count, b in enumerate(encoded_bytes):
+            if count % 8 == 0:
+                print("\n" + indent, end='', file=file)
+            else:
+                print(" ", end='', file=file)
+            print("0x{:02x},".format(b), end='', file=file)
+        print("\n" + trailer, file=file)
+        if len_format is not None:
+            print(len_format.format(len(encoded_bytes)), file=file)
+
+    def _emit_raw(self, encoded_bytes, file):
+        with FileHandler(file, 'wb') as file:
+            try:
+                # file.buffer is not part of the TextIOBase API
+                # and may not exist in some implementations.
+                file.buffer.write(encoded_bytes)
+            except AttributeError:
+                # raw binary data, can be for example io.BytesIO
+                file.write(encoded_bytes)
+
+    def emit_c_public(self, file=sys.stdout):
+        self._emit(
+                header="const unsigned char {}_pub_key[] = {{"
+                       .format(self.shortname()),
+                trailer="};",
+                encoded_bytes=self.get_public_bytes(),
+                indent="    ",
+                len_format="const unsigned int {}_pub_key_len = {{}};"
+                           .format(self.shortname()),
+                file=file)
+
+    def emit_c_public_hash(self, file=sys.stdout):
+        digest = Hash(SHA256())
+        digest.update(self.get_public_bytes())
+        self._emit(
+                header="const unsigned char {}_pub_key_hash[] = {{"
+                       .format(self.shortname()),
+                trailer="};",
+                encoded_bytes=digest.finalize(),
+                indent="    ",
+                len_format="const unsigned int {}_pub_key_hash_len = {{}};"
+                           .format(self.shortname()),
+                file=file)
+
+    def emit_raw_public(self, file=sys.stdout):
+        self._emit_raw(self.get_public_bytes(), file=file)
+
+    def emit_raw_public_hash(self, file=sys.stdout):
+        digest = Hash(SHA256())
+        digest.update(self.get_public_bytes())
+        self._emit_raw(digest.finalize(), file=file)
+
+    def emit_rust_public(self, file=sys.stdout):
+        self._emit(
+                header="static {}_PUB_KEY: &[u8] = &["
+                       .format(self.shortname().upper()),
+                trailer="];",
+                encoded_bytes=self.get_public_bytes(),
+                indent="    ",
+                file=file)
+
+    def emit_public_pem(self, file=sys.stdout):
+        with FileHandler(file, 'w') as file:
+            print(str(self.get_public_pem(), 'utf-8'), file=file, end='')
+
+    def emit_private(self, minimal, format, file=sys.stdout):
+        self._emit(
+                header="const unsigned char enc_priv_key[] = {",
+                trailer="};",
+                encoded_bytes=self.get_private_bytes(minimal, format),
+                indent="    ",
+                len_format="const unsigned int enc_priv_key_len = {};",
+                file=file)

bootloader/mcuboot/scripts/imgtool/keys/privatebytes.py

@@ -0,0 +1,16 @@
+# SPDX-License-Identifier: Apache-2.0
+
+from cryptography.hazmat.primitives import serialization
+
+
+class PrivateBytesMixin():
+    def _get_private_bytes(self, minimal, format, exclass):
+        if format is None:
+            format = self._DEFAULT_FORMAT
+        if format not in self._VALID_FORMATS:
+            raise exclass("{} does not support {}".format(
+                self.shortname(), format))
+        return format, self.key.private_bytes(
+                encoding=serialization.Encoding.DER,
+                format=self._VALID_FORMATS[format],
+                encryption_algorithm=serialization.NoEncryption())

bootloader/mcuboot/scripts/imgtool/keys/rsa.py

@@ -0,0 +1,173 @@
+"""
+RSA Key management
+"""
+
+# SPDX-License-Identifier: Apache-2.0
+
+from cryptography.hazmat.backends import default_backend
+from cryptography.hazmat.primitives import serialization
+from cryptography.hazmat.primitives.asymmetric import rsa
+from cryptography.hazmat.primitives.asymmetric.padding import PSS, MGF1
+from cryptography.hazmat.primitives.hashes import SHA256
+
+from .general import KeyClass
+from .privatebytes import PrivateBytesMixin
+
+
+# Sizes that bootutil will recognize
+RSA_KEY_SIZES = [2048, 3072]
+
+
+class RSAUsageError(Exception):
+    pass
+
+
+class RSAPublic(KeyClass):
+    """The public key can only do a few operations"""
+    def __init__(self, key):
+        self.key = key
+
+    def key_size(self):
+        return self.key.key_size
+
+    def shortname(self):
+        return "rsa"
+
+    def _unsupported(self, name):
+        raise RSAUsageError("Operation {} requires private key".format(name))
+
+    def _get_public(self):
+        return self.key
+
+    def get_public_bytes(self):
+        # The key embedded into MCUboot is in PKCS1 format.
+        return self._get_public().public_bytes(
+                encoding=serialization.Encoding.DER,
+                format=serialization.PublicFormat.PKCS1)
+
+    def get_public_pem(self):
+        return self._get_public().public_bytes(
+                encoding=serialization.Encoding.PEM,
+                format=serialization.PublicFormat.SubjectPublicKeyInfo)
+
+    def get_private_bytes(self, minimal, format):
+        self._unsupported('get_private_bytes')
+
+    def export_private(self, path, passwd=None):
+        self._unsupported('export_private')
+
+    def export_public(self, path):
+        """Write the public key to the given file."""
+        pem = self._get_public().public_bytes(
+                encoding=serialization.Encoding.PEM,
+                format=serialization.PublicFormat.SubjectPublicKeyInfo)
+        with open(path, 'wb') as f:
+            f.write(pem)
+
+    def sig_type(self):
+        return "PKCS1_PSS_RSA{}_SHA256".format(self.key_size())
+
+    def sig_tlv(self):
+        return"RSA{}".format(self.key_size())
+
+    def sig_len(self):
+        return self.key_size() / 8
+
+    def verify(self, signature, payload):
+        k = self.key
+        if isinstance(self.key, rsa.RSAPrivateKey):
+            k = self.key.public_key()
+        return k.verify(signature=signature, data=payload,
+                        padding=PSS(mgf=MGF1(SHA256()), salt_length=32),
+                        algorithm=SHA256())
+
+
+class RSA(RSAPublic, PrivateBytesMixin):
+    """
+    Wrapper around an RSA key, with imgtool support.
+    """
+
+    def __init__(self, key):
+        """The key should be a private key from cryptography"""
+        self.key = key
+
+    @staticmethod
+    def generate(key_size=2048):
+        if key_size not in RSA_KEY_SIZES:
+            raise RSAUsageError("Key size {} is not supported by MCUboot"
+                                .format(key_size))
+        pk = rsa.generate_private_key(
+                public_exponent=65537,
+                key_size=key_size,
+                backend=default_backend())
+        return RSA(pk)
+
+    def _get_public(self):
+        return self.key.public_key()
+
+    def _build_minimal_rsa_privkey(self, der):
+        '''
+        Builds a new DER that only includes N/E/D/P/Q RSA parameters;
+        standard DER private bytes provided by OpenSSL also includes
+        CRT params (DP/DQ/QP) which can be removed.
+        '''
+        OFFSET_N = 7  # N is always located at this offset
+        b = bytearray(der)
+        off = OFFSET_N
+        if b[off + 1] != 0x82:
+            raise RSAUsageError("Error parsing N while minimizing")
+        len_N = (b[off + 2] << 8) + b[off + 3] + 4
+        off += len_N
+        if b[off + 1] != 0x03:
+            raise RSAUsageError("Error parsing E while minimizing")
+        len_E = b[off + 2] + 4
+        off += len_E
+        if b[off + 1] != 0x82:
+            raise RSAUsageError("Error parsing D while minimizing")
+        len_D = (b[off + 2] << 8) + b[off + 3] + 4
+        off += len_D
+        if b[off + 1] != 0x81:
+            raise RSAUsageError("Error parsing P while minimizing")
+        len_P = b[off + 2] + 3
+        off += len_P
+        if b[off + 1] != 0x81:
+            raise RSAUsageError("Error parsing Q while minimizing")
+        len_Q = b[off + 2] + 3
+        off += len_Q
+        # adjust DER size for removed elements
+        b[2] = (off - 4) >> 8
+        b[3] = (off - 4) & 0xff
+        return b[:off]
+
+    _VALID_FORMATS = {
+        'openssl': serialization.PrivateFormat.TraditionalOpenSSL
+    }
+    _DEFAULT_FORMAT = 'openssl'
+
+    def get_private_bytes(self, minimal, format):
+        _, priv = self._get_private_bytes(minimal, format, RSAUsageError)
+        if minimal:
+            priv = self._build_minimal_rsa_privkey(priv)
+        return priv
+
+    def export_private(self, path, passwd=None):
+        """Write the private key to the given file, protecting it with the
+        optional password."""
+        if passwd is None:
+            enc = serialization.NoEncryption()
+        else:
+            enc = serialization.BestAvailableEncryption(passwd)
+        pem = self.key.private_bytes(
+                encoding=serialization.Encoding.PEM,
+                format=serialization.PrivateFormat.PKCS8,
+                encryption_algorithm=enc)
+        with open(path, 'wb') as f:
+            f.write(pem)
+
+    def sign(self, payload):
+        # The verification code only allows the salt length to be the
+        # same as the hash length, 32.
+        return self.key.sign(
+                data=payload,
+                padding=PSS(mgf=MGF1(SHA256()), salt_length=32),
+                algorithm=SHA256())

bootloader/mcuboot/scripts/imgtool/keys/rsa_test.py

@@ -0,0 +1,136 @@
+"""
+Tests for RSA keys
+"""
+
+# SPDX-License-Identifier: Apache-2.0
+
+import io
+import os
+import sys
+import tempfile
+import unittest
+
+from cryptography.exceptions import InvalidSignature
+from cryptography.hazmat.primitives.asymmetric.padding import PSS, MGF1
+from cryptography.hazmat.primitives.hashes import SHA256
+
+# Setup sys path so 'imgtool' is in it.
+sys.path.insert(0, os.path.abspath(os.path.join(os.path.dirname(__file__),
+                                                '../..')))
+
+from imgtool.keys import load, RSA, RSAUsageError
+from imgtool.keys.rsa import RSA_KEY_SIZES
+
+
+class KeyGeneration(unittest.TestCase):
+
+    def setUp(self):
+        self.test_dir = tempfile.TemporaryDirectory()
+
+    def tname(self, base):
+        return os.path.join(self.test_dir.name, base)
+
+    def tearDown(self):
+        self.test_dir.cleanup()
+
+    def test_keygen(self):
+        # Try generating a RSA key with non-supported size
+        with self.assertRaises(RSAUsageError):
+            RSA.generate(key_size=1024)
+
+        for key_size in RSA_KEY_SIZES:
+            name1 = self.tname("keygen.pem")
+            k = RSA.generate(key_size=key_size)
+            k.export_private(name1, b'secret')
+
+            # Try loading the key without a password.
+            self.assertIsNone(load(name1))
+
+            k2 = load(name1, b'secret')
+
+            pubname = self.tname('keygen-pub.pem')
+            k2.export_public(pubname)
+            pk2 = load(pubname)
+
+            # We should be able to export the public key from the loaded
+            # public key, but not the private key.
+            pk2.export_public(self.tname('keygen-pub2.pem'))
+            self.assertRaises(RSAUsageError, pk2.export_private,
+                              self.tname('keygen-priv2.pem'))
+
+    def test_emit(self):
+        """Basic sanity check on the code emitters."""
+        for key_size in RSA_KEY_SIZES:
+            k = RSA.generate(key_size=key_size)
+
+            pubpem = io.StringIO()
+            k.emit_public_pem(pubpem)
+            self.assertIn("BEGIN PUBLIC KEY", pubpem.getvalue())
+            self.assertIn("END PUBLIC KEY", pubpem.getvalue())
+
+            ccode = io.StringIO()
+            k.emit_c_public(ccode)
+            self.assertIn("rsa_pub_key", ccode.getvalue())
+            self.assertIn("rsa_pub_key_len", ccode.getvalue())
+
+            hashccode = io.StringIO()
+            k.emit_c_public_hash(hashccode)
+            self.assertIn("rsa_pub_key_hash", hashccode.getvalue())
+            self.assertIn("rsa_pub_key_hash_len", hashccode.getvalue())
+
+            rustcode = io.StringIO()
+            k.emit_rust_public(rustcode)
+            self.assertIn("RSA_PUB_KEY", rustcode.getvalue())
+
+            # raw data - bytes
+            pubraw = io.BytesIO()
+            k.emit_raw_public(pubraw)
+            self.assertTrue(len(pubraw.getvalue()) > 0)
+
+            hashraw = io.BytesIO()
+            k.emit_raw_public_hash(hashraw)
+            self.assertTrue(len(hashraw.getvalue()) > 0)
+
+    def test_emit_pub(self):
+        """Basic sanity check on the code emitters, from public key."""
+        pubname = self.tname("public.pem")
+        for key_size in RSA_KEY_SIZES:
+            k = RSA.generate(key_size=key_size)
+            k.export_public(pubname)
+
+            k2 = load(pubname)
+
+            ccode = io.StringIO()
+            k2.emit_c_public(ccode)
+            self.assertIn("rsa_pub_key", ccode.getvalue())
+            self.assertIn("rsa_pub_key_len", ccode.getvalue())
+
+            rustcode = io.StringIO()
+            k2.emit_rust_public(rustcode)
+            self.assertIn("RSA_PUB_KEY", rustcode.getvalue())
+
+    def test_sig(self):
+        for key_size in RSA_KEY_SIZES:
+            k = RSA.generate(key_size=key_size)
+            buf = b'This is the message'
+            sig = k.sign(buf)
+
+            # The code doesn't have any verification, so verify this
+            # manually.
+            k.key.public_key().verify(
+                signature=sig,
+                data=buf,
+                padding=PSS(mgf=MGF1(SHA256()), salt_length=32),
+                algorithm=SHA256())
+
+            # Modify the message to make sure the signature fails.
+            self.assertRaises(InvalidSignature,
+                              k.key.public_key().verify,
+                              signature=sig,
+                              data=b'This is thE message',
+                              padding=PSS(mgf=MGF1(SHA256()), salt_length=32),
+                              algorithm=SHA256())
+
+
+if __name__ == '__main__':
+    unittest.main()

bootloader/mcuboot/scripts/imgtool/keys/x25519.py

@@ -0,0 +1,119 @@
+"""
+X25519 key management
+"""
+
+# SPDX-License-Identifier: Apache-2.0
+
+from cryptography.hazmat.backends import default_backend
+from cryptography.hazmat.primitives import serialization
+from cryptography.hazmat.primitives.asymmetric import x25519
+
+from .general import KeyClass
+from .privatebytes import PrivateBytesMixin
+
+
+class X25519UsageError(Exception):
+    pass
+
+
+class X25519Public(KeyClass):
+    def __init__(self, key):
+        self.key = key
+
+    def shortname(self):
+        return "x25519"
+
+    def _unsupported(self, name):
+        raise X25519UsageError("Operation {} requires private key".format(name))
+
+    def _get_public(self):
+        return self.key
+
+    def get_public_bytes(self):
+        # The key is embedded into MBUboot in "SubjectPublicKeyInfo" format
+        return self._get_public().public_bytes(
+                encoding=serialization.Encoding.DER,
+                format=serialization.PublicFormat.SubjectPublicKeyInfo)
+
+    def get_public_pem(self):
+        return self._get_public().public_bytes(
+                encoding=serialization.Encoding.PEM,
+                format=serialization.PublicFormat.SubjectPublicKeyInfo)
+
+    def get_private_bytes(self, minimal, format):
+        self._unsupported('get_private_bytes')
+
+    def export_private(self, path, passwd=None):
+        self._unsupported('export_private')
+
+    def export_public(self, path):
+        """Write the public key to the given file."""
+        pem = self._get_public().public_bytes(
+                encoding=serialization.Encoding.PEM,
+                format=serialization.PublicFormat.SubjectPublicKeyInfo)
+        with open(path, 'wb') as f:
+            f.write(pem)
+
+    def sig_type(self):
+        return "X25519"
+
+    def sig_tlv(self):
+        return "X25519"
+
+    def sig_len(self):
+        return 32
+
+
+class X25519(X25519Public, PrivateBytesMixin):
+    """
+    Wrapper around an X25519 private key.
+    """
+
+    def __init__(self, key):
+        """key should be an instance of EllipticCurvePrivateKey"""
+        self.key = key
+
+    @staticmethod
+    def generate():
+        pk = x25519.X25519PrivateKey.generate()
+        return X25519(pk)
+
+    def _get_public(self):
+        return self.key.public_key()
+
+    _VALID_FORMATS = {
+        'pkcs8': serialization.PrivateFormat.PKCS8
+    }
+    _DEFAULT_FORMAT = 'pkcs8'
+
+    def get_private_bytes(self, minimal, format):
+        _, priv = self._get_private_bytes(minimal, format,
+                                          X25519UsageError)
+        return priv
+
+    def export_private(self, path, passwd=None):
+        """
+        Write the private key to the given file, protecting it with the
+        optional password.
+        """
+        if passwd is None:
+            enc = serialization.NoEncryption()
+        else:
+            enc = serialization.BestAvailableEncryption(passwd)
+        pem = self.key.private_bytes(
+                encoding=serialization.Encoding.PEM,
+                format=serialization.PrivateFormat.PKCS8,
+                encryption_algorithm=enc)
+        with open(path, 'wb') as f:
+            f.write(pem)
+
+    def sign_digest(self, digest):
+        """Return the actual signature"""
+        return self.key.sign(data=digest)
+
+    def verify_digest(self, signature, digest):
+        """Verify that signature is valid for given digest"""
+        k = self.key
+        if isinstance(self.key, x25519.X25519PrivateKey):
+            k = self.key.public_key()
+        return k.verify(signature=signature, data=digest)