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trezor-firmware/tools/snippets/recalc_optiga_for_emulator.py

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import sys
from pathlib import Path
from pyasn1.codec.der.encoder import encode
from pyasn1.codec.der.decoder import decode
from pyasn1.type.univ import BitString
from pyasn1_modules import rfc2459
from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.primitives.asymmetric import ec
def load_certificate(data: bytes):
return decode(data, asn1Spec=rfc2459.Certificate())[0]
def save_certificate(certificate) -> bytes:
return encode(certificate)
def calculate_ecdsa_public_key():
privkey_bytes = b"\x01" + b"\x00" * 31
private_key = ec.derive_private_key(
int.from_bytes(privkey_bytes, "big"), ec.SECP256R1()
)
return private_key.public_key()
def replace_public_key(certificate, public_key):
public_key_bytes = public_key.public_bytes(
encoding=serialization.Encoding.X962,
format=serialization.PublicFormat.UncompressedPoint,
)
certificate["tbsCertificate"]["subjectPublicKeyInfo"]["subjectPublicKey"] = (
BitString(hexValue=public_key_bytes.hex())
)
def main():
in_cert = Path(sys.argv[1])
certificate = load_certificate(in_cert.read_bytes())
public_key = calculate_ecdsa_public_key()
replace_public_key(certificate, public_key)
updated_cert = save_certificate(certificate)
out_cert = Path(sys.argv[2])
out_cert.write_bytes(updated_cert)
if __name__ == "__main__":
main()