Convert JWK(JSON Web Key) to Private Key(PEM)

jwk_to_pem.py

#!/usr/bin/env python3
#
# pip install cryptography, pyjwt

from jwt.utils import (
    base64url_decode,
    bytes_to_number,
)
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.primitives.asymmetric import ec


jwk = {
    "kty": "EC",
    "crv": "P-384",
    "x": "Y554xTwvkMJRVpnYomIAG92Zz3abhcO9iXOr3GRCQFMT69J51tShRWF25VfRjn-i",
    "y": "l84NkNv5BYHZx6zj7Jdp2KldqAq5cfU7PkwZuawR-LJ7TNAoiq8jtMRmBbh70Ibp",
    "d": "0FWZxB4ChgU2lAmFNUvbLk_sGXtf37HQnxKp3p85eIyatCbcQpEbtyUqx9wamuT_"
}

pub_number = ec.EllipticCurvePublicNumbers(
    x=bytes_to_number(base64url_decode(jwk['x'])),
    y=bytes_to_number(base64url_decode(jwk['y'])),
    curve=ec.SECP384R1(),
)
priv_key = ec.EllipticCurvePrivateNumbers(
    bytes_to_number(base64url_decode(jwk['d'])),
    pub_number).private_key(default_backend())

print(priv_key.private_bytes(
    encoding=serialization.Encoding.PEM,
    format=serialization.PrivateFormat.PKCS8,
    encryption_algorithm=serialization.NoEncryption()
).decode('ascii'))

# -----BEGIN PRIVATE KEY-----
# MIG2AgEAMBAGByqGSM49AgEGBSuBBAAiBIGeMIGbAgEBBDDQVZnEHgKGBTaUCYU1
# S9suT+wZe1/fsdCfEqnenzl4jJq0JtxCkRu3JSrH3Bqa5P+hZANiAARjnnjFPC+Q
# wlFWmdiiYgAb3ZnPdpuFw72Jc6vcZEJAUxPr0nnW1KFFYXblV9GOf6KXzg2Q2/kF
# gdnHrOPsl2nYqV2oCrlx9Ts+TBm5rBH4sntM0CiKryO0xGYFuHvQhuk=
# -----END PRIVATE KEY-----