diff options
author | César Belley <cesar.belley@lse.epita.fr> | 2020-08-26 13:42:07 +0200 |
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committer | Gerd Hoffmann <kraxel@redhat.com> | 2020-08-31 08:23:39 +0200 |
commit | dea01f66811b6963f306a7dcffe001fb4637662f (patch) | |
tree | e28e803670905171740526bb95e2eec1602f2c09 /scripts | |
parent | c81737e537d63ff9641792c95a88bb15386c1a1e (diff) |
scripts: Add u2f-setup-gen script
This patch adds the script used to generate setup directories, needed
for the device u2f-emulated configuration in directory mode:
python u2f-setup-gen.py $DIR
qemu -usb -device u2f-emulated,dir=$DIR
Signed-off-by: César Belley <cesar.belley@lse.epita.fr>
Message-id: 20200826114209.28821-11-cesar.belley@lse.epita.fr
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Diffstat (limited to 'scripts')
-rwxr-xr-x | scripts/u2f-setup-gen.py | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/scripts/u2f-setup-gen.py b/scripts/u2f-setup-gen.py new file mode 100755 index 0000000000..2122598fed --- /dev/null +++ b/scripts/u2f-setup-gen.py @@ -0,0 +1,170 @@ +#!/usr/bin/env python3 +# +# Libu2f-emu setup directory generator for USB U2F key emulation. +# +# Copyright (c) 2020 César Belley <cesar.belley@lse.epita.fr> +# Written by César Belley <cesar.belley@lse.epita.fr> +# +# This work is licensed under the terms of the GNU GPL, version 2 +# or, at your option, any later version. See the COPYING file in +# the top-level directory. + +import sys +import os +from random import randint +from typing import Tuple + +from cryptography.hazmat.backends import default_backend +from cryptography.hazmat.primitives.asymmetric import ec +from cryptography.hazmat.primitives.serialization import Encoding, \ + NoEncryption, PrivateFormat, PublicFormat +from OpenSSL import crypto + + +def write_setup_dir(dirpath: str, privkey_pem: bytes, cert_pem: bytes, + entropy: bytes, counter: int) -> None: + """ + Write the setup directory. + + Args: + dirpath: The directory path. + key_pem: The private key PEM. + cert_pem: The certificate PEM. + entropy: The 48 bytes of entropy. + counter: The counter value. + """ + # Directory + os.mkdir(dirpath) + + # Private key + with open(f'{dirpath}/private-key.pem', 'bw') as f: + f.write(privkey_pem) + + # Certificate + with open(f'{dirpath}/certificate.pem', 'bw') as f: + f.write(cert_pem) + + # Entropy + with open(f'{dirpath}/entropy', 'wb') as f: + f.write(entropy) + + # Counter + with open(f'{dirpath}/counter', 'w') as f: + f.write(f'{str(counter)}\n') + + +def generate_ec_key_pair() -> Tuple[str, str]: + """ + Generate an ec key pair. + + Returns: + The private and public key PEM. + """ + # Key generation + privkey = ec.generate_private_key(ec.SECP256R1, default_backend()) + pubkey = privkey.public_key() + + # PEM serialization + privkey_pem = privkey.private_bytes(encoding=Encoding.PEM, + format=PrivateFormat.TraditionalOpenSSL, + encryption_algorithm=NoEncryption()) + pubkey_pem = pubkey.public_bytes(encoding=Encoding.PEM, + format=PublicFormat.SubjectPublicKeyInfo) + return privkey_pem, pubkey_pem + + +def generate_certificate(privkey_pem: str, pubkey_pem: str) -> str: + """ + Generate a x509 certificate from a key pair. + + Args: + privkey_pem: The private key PEM. + pubkey_pem: The public key PEM. + + Returns: + The certificate PEM. + """ + # Convert key pair + privkey = crypto.load_privatekey(crypto.FILETYPE_PEM, privkey_pem) + pubkey = crypto.load_publickey(crypto.FILETYPE_PEM, pubkey_pem) + + # New x509v3 certificate + cert = crypto.X509() + cert.set_version(0x2) + + # Serial number + cert.set_serial_number(randint(1, 2 ** 64)) + + # Before / After + cert.gmtime_adj_notBefore(0) + cert.gmtime_adj_notAfter(4 * (365 * 24 * 60 * 60)) + + # Public key + cert.set_pubkey(pubkey) + + # Subject name and issueer + cert.get_subject().CN = "U2F emulated" + cert.set_issuer(cert.get_subject()) + + # Extensions + cert.add_extensions([ + crypto.X509Extension(b"subjectKeyIdentifier", + False, b"hash", subject=cert), + ]) + cert.add_extensions([ + crypto.X509Extension(b"authorityKeyIdentifier", + False, b"keyid:always", issuer=cert), + ]) + cert.add_extensions([ + crypto.X509Extension(b"basicConstraints", True, b"CA:TRUE") + ]) + + # Signature + cert.sign(privkey, 'sha256') + + return crypto.dump_certificate(crypto.FILETYPE_PEM, cert) + + +def generate_setup_dir(dirpath: str) -> None: + """ + Generates the setup directory. + + Args: + dirpath: The directory path. + """ + # Key pair + privkey_pem, pubkey_pem = generate_ec_key_pair() + + # Certificate + certificate_pem = generate_certificate(privkey_pem, pubkey_pem) + + # Entropy + entropy = os.urandom(48) + + # Counter + counter = 0 + + # Write + write_setup_dir(dirpath, privkey_pem, certificate_pem, entropy, counter) + + +def main() -> None: + """ + Main function + """ + # Dir path + if len(sys.argv) != 2: + sys.stderr.write(f'Usage: {sys.argv[0]} <setup_dir>\n') + exit(2) + dirpath = sys.argv[1] + + # Dir non existence + if os.path.exists(dirpath): + sys.stderr.write(f'Directory: {dirpath} already exists.\n') + exit(1) + + generate_setup_dir(dirpath) + + +if __name__ == '__main__': + main() |