# Authentication

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

- Token-based authentication: Requests are authenticated using a token.
- AK/SK-based authentication: Requests are authenticated by encrypting the request body using an AK/SK pair. AK/SK-based authentication is recommended because it is more secure than token-based authentication.

#### Token-based 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 a request to get permissions for calling the API.

When calling the API to obtain a user token, you must set auth.scope in the request body to project.

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

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, the API used to query a connection list. For example, if the token is ABCDEFJ...., X-Auth-Token: ABCDEFJ.... can be added to a request as follows:

    GET https://{{endpoint}}/v1/{project_id}/connections
    Content-Type: application/json
    X-Auth-Token: ABCDEFJ....

#### AK/SK-based Authentication

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

In AK/SK-based 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 used in conjunction with an AK to sign requests cryptographically. It identifies a request sender and prevents the request from being modified.

To obtain an access key, perform the following steps:

1. Log in to the management console, move the cursor to the username in the upper right corner, and select My Credentials from the drop-down list.
2. On the My Credentials page, choose Access Keys, and click Create Access Key. See Figure 1.
   Figure 1 Clicking Create Access Key
3. Click OK and save the access key file as prompted. The access key file will be saved to your browser's configured download location. Open the credentials.csv file to view Access Key Id and Secret Access Key.

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

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

Parent topic: Calling APIs