'Factory constructor from JSON keyfile.
Args:
service_account_email: string, The email associated with the
service account.
private_key_pkcs12: string, The contents of a PKCS#12 keyfile.
private_key_password: string, (Optional) Password for PKCS#12
private key. Defaults to ``notasecret``.
scopes: List or string, (Optional) Scopes to use when acquiring an
access token.
token_uri: string, URI for token endpoint. For convenience defaults
to Google\'s endpoints but any OAuth 2.0 provider can be
used.
revoke_uri: string, URI for revoke endpoint. For convenience
defaults to Google\'s endpoints but any OAuth 2.0
provider can be used.
Returns:
ServiceAccountCredentials, a credentials object created from
the keyfile.
Raises:
NotImplementedError if pyOpenSSL is not installed / not the
active crypto library.'

@classmethod
def _from_p12_keyfile_contents(cls, service_account_email, private_key_pkcs12, private_key_password=None, scopes='', token_uri=oauth2client.GOOGLE_TOKEN_URI, revoke_uri=oauth2client.GOOGLE_REVOKE_URI):

    if (private_key_password is None):
        private_key_password = _PASSWORD_DEFAULT
    if (crypt.Signer is not crypt.OpenSSLSigner):
        raise NotImplementedError(_PKCS12_ERROR)
    signer = crypt.Signer.from_string(private_key_pkcs12, private_key_password)
    credentials = cls(service_account_email, signer, scopes=scopes, token_uri=token_uri, revoke_uri=revoke_uri)
    credentials._private_key_pkcs12 = private_key_pkcs12
    credentials._private_key_password = private_key_password
    return credentials
