Register a new account with an ACME server.

acme_register.py

import hashlib
import json
import os
import platform
from datetime import datetime, UTC

from acme.client import ClientNetwork, ClientV2
from acme.messages import NewRegistration
from cryptography.hazmat.primitives.asymmetric.ec import generate_private_key, SECP256R1
from cryptography.hazmat.primitives.serialization import Encoding, PublicFormat
from josepy import ES256, JWKEC


def register(
    email: str | None,
    *,
    output_dir: str | None = None,
    server: str = "https://acme-staging-v02.api.letsencrypt.org/directory",
) -> None:
    """Register a new account with an ACME server.

    The sole reason you would use this instead of `certbot register` is to
    get an ECDSA account key; currently (2024-01-11) Certbot has no option
    to change the key type for account keys.
    """
    if output_dir is not None:
        os.chdir(output_dir)

    key = generate_private_key(SECP256R1())
    jwk = JWKEC(key=key)
    network = ClientNetwork(jwk, alg=ES256)
    directory = ClientV2.get_directory(server, network)
    acme = ClientV2(directory, network)
    regr = acme.new_account(
        NewRegistration.from_data(email=email, terms_of_service_agreed=True)
    )
    hasher = hashlib.md5()
    hasher.update(
        key.public_key().public_bytes(
            encoding=Encoding.PEM,
            format=PublicFormat.SubjectPublicKeyInfo,
        )
    )
    public_key_hash = hasher.hexdigest()

    print(f"Key:\n{jwk.json_dumps_pretty()}")
    print(f"Account URI: {regr.uri}")
    print(f"Public key hash: {public_key_hash}")

    os.mkdir(public_key_hash, mode=0o700)
    os.chdir(public_key_hash)
    os.umask(0o177)

    with open("private_key.json", "x") as f:
        json.dump(jwk, f, default=jwk.json_dump_default)

    with open("regr.json", "x") as f:
        json.dump(regr, f, default=regr.json_dump_default)

    with open("meta.json", "x") as f:
        meta = {
            "creation_dt": datetime.now(UTC).strftime("%Y-%m-%dT%H:%M:%SZ"),
            "creation_host": platform.node(),
        }
        json.dump(meta, f)