CadesSignMessage failed (error 0x8009200b).

[ogremagi4]

Подскажите, каким образом привязать private.key к самоподписанному x509 сертификату, чтобы Cades смог подписывать контент?

from OpenSSL import crypto
from pycryptoprosdk import CryptoProSDK

CERT_FILE = "selfsigned.crt"
PRIVATE_KEY_FILE = "private.key"
PUBLIC_KEY_FILE = "public.key"
COMMON_NAME = 'Фамилия Имя Отчество'

def raw_cert(bytes_content):
    return ('\n'.join(bytes_content.decode().split('\n')[1:-2])+'\n').encode()

def create_self_signed_cert(common_name=COMMON_NAME, country='RU', state = 'Test state', city='Test city', organization='test organization', organizational_unit = 'test organizational unit'):
        # create a key pair
        k = crypto.PKey()
        k.generate_key(crypto.TYPE_RSA, 1024)
        # create a self-signed cert
        cert = crypto.X509()
        cert.get_subject().C = country
        cert.get_subject().ST = state
        cert.get_subject().L = city
        cert.get_subject().O = organization
        cert.get_subject().OU = organizational_unit
        cert.get_subject().CN = common_name
        cert.set_serial_number(1000)
        cert.gmtime_adj_notBefore(0)
        cert.gmtime_adj_notAfter(10*365*24*60*60)#10 years
        cert.set_issuer(cert.get_subject())
        cert.set_pubkey(k)
        cert.sign(k, 'sha1')

        open(CERT_FILE, "wb+").write(
            crypto.dump_certificate(crypto.FILETYPE_PEM, cert))
        open(PRIVATE_KEY_FILE, "wb+").write(
            crypto.dump_privatekey(crypto.FILETYPE_PEM, k))
        open(PUBLIC_KEY_FILE, "wb+").write(
            crypto.dump_publickey(crypto.FILETYPE_PEM, k))

create_self_signed_cert() #creates selfsigned.crt, public.key, private.key
sdk = CryptoProSDK()
sdk.install_certificate('MY', raw_cert(open(CERT_FILE, 'rb').read()))
content = "test content"
cert = sdk.get_cert_by_subject('MY',COMMON_NAME)
signature = sdk.sign(content, cert.thumbprint, 'MY', detached=True)

"""
Exception has occurred: ValueError       (note: full exception trace is shown but execution is paused at: _run_module_as_main)
CadesSignMessage failed (error 0x8009200b).
"""