The Authorization header is a JWS (signed JWT) that includes few standard claims, plus the digest computed as described above. Below there is a complete example in Python with the relevant comments. Once you compute the JWS, just add it to every request as an Authorization header:
For some programming languages, Google provides libraries/wrappers for signing payloads, but this may be achieved in any programming language using standard libraries.
import time
import google.auth.crypt
import google.auth.jwt
import hashlib
import json
import base64
def generate_jwt():
now = int(time.time())
payload = {
"client_id": "51e2389....02d51",
"client_app_key": "MDAxNmxvY2F0aWMz...D9rgv7_DySaiYgo",
"skill": "bt_ro_aisp_sbx_#2.0"
}
# a compact stringified json without any whitespaces
json_payload = json.dumps(payload, separators=(',', ':')).encode("utf-8")
digest = hashlib.sha256(json_payload).digest()
b64_digest = base64.b64encode(digest).decode("utf-8")
# service account email: this is auto-generated by GCP when creating a service account
sa_email='service-account1@my-gcp-project.iam.gserviceaccount.com'
# how long this JWS should be valid for.
# - each request will have its own JWS so this value should be small
expiry_length=3600
# build the payload for your signed Authorization header
payload = {
'iat': now,
# expires after 'expiry_length' seconds.
"exp": now + expiry_length,
# iss (issuer) should match the service account's email address
'iss': sa_email,
# aud (audience) is alwasy ('api.finqware.com')
'aud': 'api.finqware.com',
# sub and email should match the service account's email address
'sub': sa_email,
'email': sa_email,
# a Base64 encoded sha-256 hash of the request payload as described above
'digest': b64_digest
}
# the signing/private key is inside this json file downloaded when creating
# a public/private key pair for a service account
sa_keyfile='my-gcp-private-key.json',
# sign with your service account keyfile
signer = google.auth.crypt.RSASigner.from_service_account_file(sa_keyfile)
jwt = google.auth.jwt.encode(signer, payload)
return jwt
if __name__ == '__main__':
jwt = generate_jwt()
print(jwt)
