sign_mac.py

# Copyright 2021 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and


# [START kms_sign_mac]
def sign_mac(project_id, location_id, key_ring_id, key_id, version_id, data):
    """
    Sign a message using the public key part of an asymmetric key.

    Args:
        project_id (string): Google Cloud project ID (e.g. 'my-project').
        location_id (string): Cloud KMS location (e.g. 'us-east1').
        key_ring_id (string): ID of the Cloud KMS key ring (e.g. 'my-key-ring').
        key_id (string): ID of the key to use (e.g. 'my-key').
        version_id (string): Version to use (e.g. '1').
        data (string): Data to sign.

    Returns:
        MacSignResponse: Signature.
    """

    # Import the client library.
    from google.cloud import kms

    # Import base64 for printing the ciphertext.
    import base64

    # Create the client.
    client = kms.KeyManagementServiceClient()

    # Build the key version name.
    key_version_name = client.crypto_key_version_path(project_id, location_id, key_ring_id, key_id, version_id)

    # Convert the message to bytes.
    data_bytes = data.encode('utf-8')

    # Call the API
    sign_response = client.mac_sign(
        request={'name': key_version_name, 'data': data_bytes})

    print('Signature: {}'.format(base64.b64encode(sign_response.mac)))
    return sign_response
# [END kms_sign_mac]