Requests for calling an API can be authenticated using either of the following methods:

Token authentication: Requests are authenticated using tokens.
AK/SK authentication: Requests are encrypted using AK/SK pairs. AK/SK authentication is recommended because it is more secure than token authentication.

Token Authentication

The validity period of a token is 24 hours. When using a token for authentication, cache it to prevent frequently calling the IAM API used to obtain a user token.

A token specifies temporary permissions in a computer system. During API authentication using a token, the token is added to requests to get permissions for calling the API. You can obtain a token by calling the Obtaining User Token API.

A cloud service can be deployed as either a project-level service or global service.

For a project-level service, you need to obtain a project-level token. When you call the API, set auth.scope in the request body to project.
For a global service, you need to obtain a global token. When you call the API, set auth.scope in the request body to domain.

IMS is a project-level service. When you call the API, set auth.scope in the request body to project.

{
    "auth": {
        "identity": {
            "methods": [
                "password"
            ],
            "password": {
                "user": {
                    "name": "username",
                    "password": "********",
                    "domain": {
                        "name": "domainname"
                    }
                }
            }
        },
        "scope": {
            "project": {
                "name": "xxxxxxxx"
            }
        }
    }
}

After a token is obtained, the X-Auth-Token header field must be added to requests to specify the token when calling other APIs. For example, if the token is ABCDEFJ...., X-Auth-Token: ABCDEFJ.... can be added to a request as follows:

POST https://{{endpoint}}/v3/auth/projects
Content-Type: application/json
X-Auth-Token: ABCDEFJ....

AK/SK Authentication

AK/SK authentication supports API requests with a body not larger than 12 MB. For API requests with a larger body, token authentication is recommended.

In AK/SK authentication, AK/SK is used to sign requests and the signature is then added to the requests for authentication.

AK: access key ID, which is a unique identifier used in conjunction with a secret access key to sign requests cryptographically.
SK: secret access key, which is used in conjunction with an AK to sign requests cryptographically. It identifies a request sender and prevents the request from being modified.

In AK/SK authentication, you can use an AK/SK to sign requests based on the signature algorithm or using the signing SDK.

The signing SDK is only used for signing requests and is different from the SDKs provided by services.