scripts/bootloader: Add ed25519/sha512 to scripts

Python scripts implementing ed25519 and sha512 support needed
for nsib image signing.

Signed-off-by: Lukasz Fundakowski <[email protected]>

scripts/bootloader/asn1parse.py

@@ -5,13 +5,15 @@
 # SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
 
 
-from subprocess import check_output
+import argparse
 import re
 import sys
-import argparse
+from subprocess import check_output
 
+from cryptography.hazmat.primitives.asymmetric import ed25519
 
-def get_ecdsa_signature(der, clength):
+
+def get_ecdsa_signature(der: bytes, clength: int) -> bytes:
     # The der consists of a SEQUENCE with 2 INTEGERS (r and s)
     # The expected byte format of the file is
     #  0:        type(SEQ), len(SEQ)
@@ -24,7 +26,7 @@ def get_ecdsa_signature(der, clength):
     # leading 0 byte.
     # clength is the expected length of r and s.
     # The following code parses the output of openssl asnparse which prints
-    # the values in hex, together with human-readble metadata.
+    # the values in hex, together with human-readable metadata.
 
     # Disable pylint error as 'input' keyword has specific handling in 'check_output'
     # pylint: disable=unexpected-keyword-arg
@@ -36,13 +38,19 @@ def get_ecdsa_signature(der, clength):
     return sig
 
 
+def get_ed25519_signature(der: bytes) -> bytes:
+    private_key = ed25519.Ed25519PrivateKey.generate()
+    signature = private_key.sign(der)
+    return signature
+
+
 def parse_args():
     parser = argparse.ArgumentParser(
         description='Decode DER format using OpenSSL.',
         formatter_class=argparse.RawDescriptionHelpFormatter,
         allow_abbrev=False)
 
-    parser.add_argument('-a', '--alg', required=True, choices=['rsa', 'ecdsa'],
+    parser.add_argument('-a', '--alg', required=True, choices=['rsa', 'ecdsa', 'ed25519'],
                         help='Expected algorithm')
     parser.add_argument('-c', '--contents', required=True, choices=['signature'],
                         help='Expected contents')
@@ -55,9 +63,20 @@ def parse_args():
     return args
 
 
-if __name__ == '__main__':
+def main() -> int:
     args = parse_args()
-    assert args.alg == 'ecdsa'  # Only ecdsa is currently supported.
+
     if args.alg == 'ecdsa':
         if args.contents == 'signature':
             sys.stdout.buffer.write(get_ecdsa_signature(args.infile.read(), 32))
+    elif args.alg == 'ed25519':
+        if args.contents == 'signature':
+            sys.stdout.buffer.write(get_ed25519_signature(args.infile.read()))
+    else:
+        sys.exit(f'Algorythm not supported {args.alg}')
+
+    return 0
+
+
+if __name__ == '__main__':
+    sys.exit(main())

scripts/bootloader/do_sign.py

@@ -3,19 +3,20 @@
 # Copyright (c) 2018 Nordic Semiconductor ASA
 #
 # SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
-
-
-import sys
 import argparse
 import hashlib
+import sys
+
+from cryptography.hazmat.primitives.serialization import load_pem_private_key
 from ecdsa import SigningKey
 
 
-def parse_args():
+def parse_args(argv=None):
     parser = argparse.ArgumentParser(
         description='Sign data from stdin or file.',
         formatter_class=argparse.RawDescriptionHelpFormatter,
-        allow_abbrev=False)
+        allow_abbrev=False
+    )
 
     parser.add_argument('-k', '--private-key', required=True, type=argparse.FileType('rb'),
                         help='Private key to use.')
@@ -25,15 +26,33 @@ def parse_args():
     parser.add_argument('-o', '--out', '-out', required=False, dest='outfile',
                         type=argparse.FileType('wb'), default=sys.stdout.buffer,
                         help='Write the signature to the specified file instead of stdout.')
+    parser.add_argument(
+        '--alg', '-a', dest='algorythm', help='Encryption algorythm (default: %(default)s)',
+        action='store', choices=['ecdsa', 'ed25519'], default='ecdsa',
+    )
 
-    args = parser.parse_args()
+    args = parser.parse_args(argv)
 
     return args
 
 
+def main(argv=None) -> int:
+    args = parse_args(argv)
+    if args.algorythm == 'ecdsa':
+        private_key = SigningKey.from_pem(args.private_key.read())
+        data = args.infile.read()
+        signature = private_key.sign(data, hashfunc=hashlib.sha256)
+        args.outfile.write(signature)
+        return 0
+    if args.algorythm == 'ed25519':
+        private_key = load_pem_private_key(args.private_key.read(), password=None)
+        data = args.infile.read()
+        signature = private_key.sign(data)
+        args.outfile.write(signature)
+        return 0
+
+    return 1
+
+
 if __name__ == '__main__':
-    args = parse_args()
-    private_key = SigningKey.from_pem(args.private_key.read())
-    data = args.infile.read()
-    signature = private_key.sign(data, hashfunc=hashlib.sha256)
-    args.outfile.write(signature)
+    sys.exit(main())

scripts/bootloader/hash.py

@@ -4,27 +4,43 @@
 #
 # SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
 
+"""
+Hash content of a file.
+"""
 
 import hashlib
 import sys
 import argparse
 from intelhex import IntelHex
 
 
+HASH_FUNCTION_FACTORY = {
+    'sha256': hashlib.sha256,
+    'sha512': hashlib.sha512,
+}
+
+
 def parse_args():
     parser = argparse.ArgumentParser(
         description='Hash data from file.',
         formatter_class=argparse.RawDescriptionHelpFormatter,
         allow_abbrev=False)
 
-    parser.add_argument('--infile', '-i', '--in', '-in', required=True,
-                        help='Hash the contents of the specified file. If a *.hex file is given, the contents will '
-                             'first be converted to binary, with all non-specified area being set to 0xff. '
-                             'For all other file types, no conversion is done.')
+    parser.add_argument(
+        '--infile', '-i', '--in', '-in', required=True,
+        help='Hash the contents of the specified file. If a *.hex file is given, the contents will '
+             'first be converted to binary, with all non-specified area being set to 0xff. '
+             'For all other file types, no conversion is done.'
+    )
+    parser.add_argument(
+        '--type', '-t', dest='hash_function', help='Hash function (default: %(default)s)',
+        action='store', choices=HASH_FUNCTION_FACTORY.keys(), default='sha256'
+    )
+
     return parser.parse_args()
 
 
-if __name__ == '__main__':
+def main():
     args = parse_args()
 
     if args.infile.endswith('.hex'):
@@ -33,4 +49,11 @@ def parse_args():
         to_hash = ih.tobinstr()
     else:
         to_hash = open(args.infile, 'rb').read()
-    sys.stdout.buffer.write(hashlib.sha256(to_hash).digest())
+
+    hash_function = HASH_FUNCTION_FACTORY[args.hash_function]
+    sys.stdout.buffer.write(hash_function(to_hash).digest())
+    return 0
+
+
+if __name__ == '__main__':
+    sys.exit(main())

scripts/bootloader/keygen.py

@@ -5,12 +5,14 @@
 # SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
 
 
+import argparse
+import sys
+from hashlib import sha256, sha512
+
 from cryptography.hazmat.primitives import serialization
 from cryptography.hazmat.primitives.asymmetric import ec
+from cryptography.hazmat.primitives.asymmetric import ed25519
 from cryptography.hazmat.primitives.serialization import load_pem_private_key as load_pem
-from hashlib import sha256
-import argparse
-import sys
 
 
 def generate_legal_key():
@@ -23,8 +25,8 @@ def generate_legal_key():
     while True:
         key = ec.generate_private_key(ec.SECP256R1())
         public_bytes = key.public_key().public_bytes(
-                encoding=serialization.Encoding.X962,
-                format=serialization.PublicFormat.UncompressedPoint,
+            encoding=serialization.Encoding.X962,
+            format=serialization.PublicFormat.UncompressedPoint,
         )
 
         # The digest don't contain the first byte as it denotes
@@ -35,7 +37,69 @@ def generate_legal_key():
             return key
 
 
-if __name__ == '__main__':
+def generate_legal_key_sha512():
+    """
+    Ensure that we don't have 0xFFFF in the hash of the public key of
+    the generated keypair.
+
+    :return: A key who's SHA512 digest does not contain 0xFFFF
+    """
+    while True:
+        key = ed25519.Ed25519PrivateKey.generate()
+        public_bytes = key.public_key().public_bytes(
+            encoding=serialization.Encoding.PEM,
+            format=serialization.PublicFormat.SubjectPublicKeyInfo,
+        )
+
+        # The digest don't contain the first byte as it denotes
+        # if it is compressed/UncompressedPoint.
+        digest = sha512(public_bytes[1:]).digest()[:16]
+        if not any([digest[n:n + 2] == b'\xff\xff' for n in range(0, len(digest), 2)]):
+            return key
+
+
+def encrypt_with_elliptic_curve(args):
+    """Generate private and public keys for Elliptic curve cryptography."""
+    sk = (load_pem(args.infile.read(), password=None) if args.infile else generate_legal_key())
+    if args.private:
+        private_pem = sk.private_bytes(
+            encoding=serialization.Encoding.PEM,
+            format=serialization.PrivateFormat.PKCS8,
+            encryption_algorithm=serialization.NoEncryption(),
+        )
+        args.out.write(private_pem)
+
+    if args.public:
+        public_pem = sk.public_key().public_bytes(
+            encoding=serialization.Encoding.PEM,
+            format=serialization.PublicFormat.SubjectPublicKeyInfo,
+        )
+        args.out.write(public_pem)
+
+
+def encrypt_with_ed25519(args):
+    """Generate private and public keys for ED25519 cryptography."""
+    if args.infile:
+        private_key = load_pem(args.infile.read(), password=None)
+    else:
+        private_key = generate_legal_key_sha512()
+    if args.private:
+        private_bytes = private_key.private_bytes(
+            encoding=serialization.Encoding.PEM,
+            format=serialization.PrivateFormat.PKCS8,
+            encryption_algorithm=serialization.NoEncryption()
+        )
+        args.out.write(private_bytes)
+    if args.public:
+        public_key = private_key.public_key()
+        public_bytes = public_key.public_bytes(
+            encoding=serialization.Encoding.PEM,
+            format=serialization.PublicFormat.SubjectPublicKeyInfo
+        )
+        args.out.write(public_bytes)
+
+
+def main(argv=None) -> int:
     parser = argparse.ArgumentParser(
         description='Generate PEM file.',
         formatter_class=argparse.RawDescriptionHelpFormatter,
@@ -53,21 +117,20 @@ def generate_legal_key():
                         type=argparse.FileType('rb'),
                         help='Read private key from specified PEM file instead '
                              'of generating it.')
+    parser.add_argument(
+        '--algorithm', '-a', help='Encryption Algorithm (default: %(default)s)',
+        required=False, action='store', choices=('ec', 'ed25519'), default='ec'
+    )
 
-    args = parser.parse_args()
-    sk = (load_pem(args.infile.read(), password=None) if args.infile else generate_legal_key())
+    args = parser.parse_args(argv)
 
-    if args.private:
-        private_pem = sk.private_bytes(
-                encoding=serialization.Encoding.PEM,
-                format=serialization.PrivateFormat.PKCS8,
-                encryption_algorithm=serialization.NoEncryption(),
-                )
-        args.out.write(private_pem)
+    if args.algorithm == 'ed25519':
+        encrypt_with_ed25519(args)
+    else:
+        encrypt_with_elliptic_curve(args)
 
-    if args.public:
-        public_pem = sk.public_key().public_bytes(
-                encoding=serialization.Encoding.PEM,
-                format=serialization.PublicFormat.SubjectPublicKeyInfo,
-                )
-        args.out.write(public_pem)
+    return 0
+
+
+if __name__ == '__main__':
+    sys.exit(main())