imgtool: Add generic ECDSA TLV support
Update imgtool to support the new
generic ECDSA TLV and the ECDSA
p384 curve type with sha-384
Signed-off-by: Roland Mikhel <roland.mikhel@arm.com>
Change-Id: I9b1887610cc5d0e7cde90f47999fcdf3500ef51c
diff --git a/scripts/imgtool/keys/ecdsa.py b/scripts/imgtool/keys/ecdsa.py
index addceb2..b70153c 100644
--- a/scripts/imgtool/keys/ecdsa.py
+++ b/scripts/imgtool/keys/ecdsa.py
@@ -4,11 +4,12 @@
# 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
+from cryptography.hazmat.primitives.hashes import SHA256, SHA384
from .general import KeyClass
from .privatebytes import PrivateBytesMixin
@@ -18,18 +19,18 @@
pass
-class ECDSA256P1Public(KeyClass):
+class ECDSAPublicKey(KeyClass):
+ """
+ Wrapper around an ECDSA public key.
+ """
def __init__(self, key):
self.key = key
- def shortname(self):
- return "ecdsa"
-
def _unsupported(self, name):
raise ECDSAUsageError("Operation {} requires private key".format(name))
def _get_public(self):
- return self.key
+ return self.key.public_key()
def get_public_bytes(self):
# The key is embedded into MBUboot in "SubjectPublicKeyInfo" format
@@ -56,55 +57,13 @@
with open(path, 'wb') as f:
f.write(pem)
- def sig_type(self):
- return "ECDSA256_SHA256"
- def sig_tlv(self):
- return "ECDSA256"
-
- 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(ECDSA256P1Public, PrivateBytesMixin):
+class ECDSAPrivateKey(PrivateBytesMixin):
"""
Wrapper around an ECDSA private key.
"""
-
def __init__(self, key):
- """key should be an instance of EllipticCurvePrivateKey"""
self.key = key
- self.pad_sig = False
-
- @staticmethod
- def generate():
- pk = ec.generate_private_key(
- ec.SECP256R1(),
- backend=default_backend())
- return ECDSA256P1(pk)
-
- def _get_public(self):
- return self.key.public_key()
def _build_minimal_ecdsa_privkey(self, der, format):
'''
@@ -154,13 +113,14 @@
'pkcs8': serialization.PrivateFormat.PKCS8,
'openssl': serialization.PrivateFormat.TraditionalOpenSSL
}
- _DEFAULT_FORMAT='pkcs8'
+ _DEFAULT_FORMAT = 'pkcs8'
def get_private_bytes(self, minimal, format):
- format, priv = self._get_private_bytes(minimal, format, ECDSAUsageError)
+ format, priv = self._get_private_bytes(minimal,
+ format, ECDSAUsageError)
if minimal:
- priv = self._build_minimal_ecdsa_privkey(priv,
- self._VALID_FORMATS[format])
+ priv = self._build_minimal_ecdsa_privkey(
+ priv, self._VALID_FORMATS[format])
return priv
def export_private(self, path, passwd=None):
@@ -177,6 +137,64 @@
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(ECDSA256P1Public, ECDSAPrivateKey):
+ """
+ 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(
@@ -191,3 +209,78 @@
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(ECDSA384P1Public, ECDSAPrivateKey):
+ """
+ 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